Fuel injector

Abstract

Fuel injection valve, comprising: a valve body (50) movably received in a nozzle body (30) for opening or closing an injection port (32); a pressure control chamber (71) for applying a fuel pressure to the valve body (50) in a valve body closing direction; a fixed plate (20) having a high-pressure passage (22) for supplying high-pressure fuel to the pressure control chamber (71) so as to move the valve body (50) in the valve body closing direction, and wherein the fixed plate (20) has a low-pressure passage (23) for discharging fuel from the pressure control chamber (71) so as to move the valve body in a valve body opening direction, and the fixed plate (20) has a lower end surface (25a, 25b, 26a, 26b) on which a high-pressure port (22b) connected to the high-pressure passage (22) and a low-pressure port (23c) connected to the low-pressure passage (23) are formed such that the high-pressure port (22b) surrounds the low-pressure port (23c); and a movable plate (80) movably received in the pressure control chamber (71), wherein the movable plate (80) is brought into contact with the lower end surface (25a, 25b, 26a, 26b) of the fixed plate (20) when the fuel is discharged from the pressure control chamber (71) so as to close the high-pressure port (22b), and the movable plate (80) is separated from the lower end surface (25a, 25b, 26a, 26b) of the fixed plate (20) when the high-pressure fuel is supplied to the pressure control chamber (71) so as to open the high-pressure port (22b), wherein the lower end surface has a first wall portion (25) surrounding the low-pressure port (23c) and formed between the low-pressure port (23c) and the high-pressure port (22b), the first wall portion (25) having a first contact surface (25a, 25b) for separating the high-pressure port (22b) from the low-pressure port (23c) in a plate-contact state in which the movable plate (80) is in contact with the fixed plate (20), wherein the lower end surface has a second wall portion (26) surrounding the high-pressure port (22b) and formed on an outer side of the high-pressure port (22b), the second wall portion (26) having a second contact surface (26a, 26b) for separating the high-pressure port (22b) from the outer side of the high-pressure port (22b) in the state of plate contact, wherein the movable plate (80) has a first sealing surface (82a) for sealing a space between the first contact surface (25a, 25b) and the first sealing surface (82a) in the state of plate contact, and the movable plate (80) has a second sealing surface (82b) for sealing a space between the second contact surface (26a, 26b) and the second sealing surface (82b) in the state of plate contact, and wherein a first groove (25m) is formed as a binding force reducing groove on the first contact surface (25a, 25b) to receive a part of the fuel when the movable plate (80) is brought into contact with the fixed plate (20), and a second groove (26m) is formed as a binding force reducing groove on the second contact surface (26a, 26b) to receive another part of the fuel when the movable plate (80) is brought into contact with the fixed plate (20), so that a binding force generated between the movable plate (80) and the fixed plate (20) is reduced when the movable plate (80) is separated from the fixed plate (20).

Description

The present disclosure relates to a fuel injection valve for fuel injection in an internal combustion engine.A fuel injection valve is known in the art, for example, it is disclosed in the following Japanese Patent Laid-Open Nos.Japanese Patent Application Laid-Open No. 2011-169 241Japanese Patent Application Laid-Open No. 2011-169 242 AJapanese Patent Application Laid-Open No. 2011-012 670According to the fuel injection valve disclosed in the above-mentioned related art, a fuel pressure in a fuel pressure control chamber (i.e., a back pressure of a valve body) is controlled so that the valve body is operated to open or close an injection port. In other words, the counter pressure acts on the valve body in a valve closing direction. When the fuel is discharged from the pressure control chamber to decrease the back pressure, the valve body moves in a valve opening direction. On the other hand, the valve body moves in the valve closing direction when the fuel in the pressure control chamber is supplied to increase the back pressure. A structure for the above-described operation is constituted by a fixed plate 20 and a movable plate 80 as shown in FIG. 12 attached to the present application.In FIG. 12, in the fixed plate 20, a high-pressure passage 22 for supplying a fuel under high pressure into a pressure control chamber 71 and a low-pressure passage 23 for discharging the fuel from the pressure control chamber 71 are formed. In addition, the fixed plate 20 has contact surfaces 25 sand 26 sin a lower end surface in which a high-pressure port 22 b(corresponding to an outlet port of the high-pressure passage 22) and a low-pressure port 23 c(corresponding to an inlet port of the low-pressure passage 23) are respectively formed. The movable plate 80 is brought into contact with the contact surfaces 25 sand 26 sto close the high pressure port 22 bwhen the fuel is discharged from the pressure control chamber 71. The movable plate 80 is separated from the contact surfaces 25 sand 26 sto open the high-pressure port 22 bwhen the high-pressure fuel is supplied in the pressure control chamber 71.The inventor of the present disclosure found that, as shown in FIG. 12, a binding force is generated between the fixed plate 20 and the movable plate 80 in the above-mentioned prior art structure when the movable plate 80 is separated from the fixed plate 20. The binding force is generated due to the fact that the fuel does not easily flow from the high-pressure passage 22 and / or the low-pressure passage 23 into spaces between the contact surfaces 25 sand 26 sof the fixed plate 20 and the movable plate 80.When the binding force is generated, the movable plate 80 cannot easily and smoothly separate from the fixed plate 20. A time for opening the high pressure port 22 bmay then be delayed, and thereby a response characteristic of the back pressure and a movement of the valve body in the valve closing direction decreases. In such a case, a valve opening period may become longer than intended. This may result in the problem that a fuel injection amount becomes larger than an expected amount.In addition, since the bonding force is nonuniform, a variation in the time for opening the high-pressure port 22 bmay be caused. Accordingly, a deviation of the fuel injection amount may be caused.The movable plate 80 is strongly pressed against the contact surfaces 25 sand 26 swhen the movable plate 80 is in contact with the fixed plate 20. Therefore, if areas of the contact surfaces 25 sand 26 sare merely reduced to reduce the bonding force, the contact surfaces 25 sand 26 swere liable to wear abnormally.Moreover, JP 2011-169 242 A discloses a fuel injection device, wherein a control body includes a pressure control chamber, an inflow port through which fuel flows into the control chamber, and an outflow port through which fuel flows out of the control chamber. The inflow port and the outflow port are opened in an opening wall surface exposed in the pressure control chamber. A floating plate is disposed in the pressure control chamber to separate the inflow port and the pressure control chamber by pressing the orifice wall surface with fuel pressure. The floating plate is formed with an outflow recess and a stopper protrusion on a pressing surface. When the opening wall surface is pressed by the pressing surface, the stopper protrusion also abuts against the opening wall surface in the outflow recess to prevent deformation of the floating plate.DE 10 2006 036 843 A1 discloses a fuel injection valve for the intermittent injection of fuel into the combustion chamber of an internal combustion engine, having an elongate housing and an injection valve seat, a high-pressure chamber in the housing, which chamber is connected to a high-pressure fuel inlet and the injection valve seat, an injection valve member which is guided in a longitudinally adjustable manner in the housing and interacts on the one hand with the injection valve seat in order to close and open injection openings and on the other hand has a double-acting control piston which is guided in a tight sliding fit in the housing, and having a hydraulic control device for controlling the adjusting movement of the injection valve member, having a control body which is held in the housing and has a control passage which is connected on the one, first end face of the control body to a first control chamber and which is separable from a low-pressure chamber and can be connected thereto by means of a pilot valve, a fuel supply passage which is connected to the high-pressure chamber and extends to the first end face, a fuel throttle passage which permanently connects the high-pressure chamber and the first control chamber, an annular intermediate valve body which is arranged such that it can be displaced longitudinally in the housing forming a gap and which delimits the first control chamber on the circumferential side, closes the fuel supply passage in a closed position in which it bears against the first end face of the control body and, in an open position in which it is lifted from the first end face, releases the fuel supply passage in order to connect it to the first control chamber and the gap, a piston element which is in engagement with the annular intermediate valve body, can be displaced longitudinally with respect to the latter and delimits the first control chamber, and a second control chamber which is delimited by the control piston and is separated from the first control chamber by means of the piston element, which is connected to the gap and via a throttle connection to the first control chamber and is otherwise closed.In addition, DE 10 2011 000 739 A1 discloses that, in a fuel injection device, a control housing or control body has a pressure control chamber, an inflow opening and an outflow opening. The inflow port and the outflow port are open at an abutment surface exposed to the pressure control chamber. In the pressure control chamber, a movable plate for applying a pressure to the abutting surface through a pressure surface is disposed, wherein the pressure of the fuel is to cut off communication between the inflow port and the pressure control chamber. The abutting surface of the control body is provided with an outer opposing surface portion opposite to an outer edge of the printing surface in a displacement axis direction of the movable plate, and the outer opposing surface portion has a recessed special portion recessed in the displacement axis direction and extending along the shape of the outer edge of the printing surface.The present disclosure relates to the above problem. It is an object of the present disclosure to provide a fuel injection valve according to which a movable plate can be easily separated from a fixed plate.The above object is achieved by the subject matters of the subordinate claims. Advantageous further developments of the invention are the subject of the dependent claims that follow.According to a feature of the present disclosure, a fuel injection valve includes a valve body (50), a fixed plate (20), and a movable plate (80). The valve body (50) opens or closes an injection port (32) for fuel injection, and is disposed in the fuel injection valve such that a fuel pressure of a pressure control chamber (71) is applied to the valve body (50) in a valve body closing direction. The fixed plate (20) has a high-pressure passage (22) for supplying a high-pressure fuel in the pressure control chamber (71) so as to move the valve body (50) in the valve body closing direction, and a low-pressure passage (23) for discharging fuel from the pressure control chamber (71) so as to move the valve body (50) in a valve body opening direction. In addition, the fixed plate (20) has contact surfaces (25a, 25b, 25c, 26a, 26b, 26c) in which a high-pressure port (22b) and a low-pressure port (23c) are formed, the high-pressure port (22b) corresponding to an outlet port of the high-pressure passage (22) and the low-pressure port (23c) corresponding to an inlet port of the low-pressure passage (23). The movable plate (80) is brought into contact with the contact surfaces so as to close the high pressure port (22b) when the fuel is discharged from the pressure control chamber, whereas the movable plate (80) is separated from the contact surfaces so as to open the high pressure port (22b) when the high pressure fuel is supplied in the pressure control chamber.A first recess is formed on a first contact surface (25a, 25b, 25c) among the contact surfaces of the fixed plate (20) and / or on a first sealing surface (82a) of the movable plate (80), the first contact surface separates the high pressure terminal from the low pressure terminal, and the first sealing surface is a portion of an upper end surface of the movable plate (80) that is in contact with the first contact surface in a state of plate contact. In the state of plate contact, the first recess receives the fuel.According to the above feature of the present disclosure, when the movable plate ( 80) is separated from the fixed plate ( 20) from the plate contact state (in which the first contact surface and the first seal surface are in strong contact with each other), the fuel flows from the high pressure port and the low pressure port into spaces between the first contact surface and the first seal surface (as shown by arrows A and B in FIG. 6 ). In addition, the fuel flows into the above-mentioned spaces from the first recess (as shown by arrows C and D in FIG. 6 ). As a result, the binding force generated between the fixed plate (20) and the movable plate (80) can be reduced.Therefore, it is possible to avoid a situation in which a time at which the movable plate ( 80) separates from the fixed plate ( 20) is delayed due to the bonding force, and thereby a time for opening the high-pressure port is delayed. Accordingly, it is possible to prevent a response for increasing the control pressure in the pressure control chamber (back pressure) and a movement of the valve body in the valve closing direction from decreasing.Since the bonding force can be reduced, a variation in the time for opening the high-pressure port can be reduced. In other words, a variation in time for increasing the back pressure and moving the valve body in the valve closing direction can be reduced. Finally, a variation in the fuel injection amount can be decreased.The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings. In the drawings, there are shown: FIG. 1 is a schematic sectional view showing a fuel injection valve according to a first embodiment of the present disclosure; FIG. 2 is a schematic enlarged sectional view showing relevant portions of the fuel injection valve of FIG. 1 ; FIG. 3 is a schematic enlarged sectional view showing other relevant portions of the fuel injection valve of FIG. 2 ; FIG. 4 is a schematic bottom view of a fixed plate of FIG. 3 as viewed from one side of an injection port; FIG. 5 is a schematic enlarged sectional view showing relevant portions of the fuel injection valve of FIG. 3 ; FIG. 6 is a schematic enlarged bottom view showing a relevant portion of the fixed plate indicated by a dotted line VI in FIG. 4 ; FIGS. 7A to 7F are timing charts for explaining an operation of the fuel injection valve of the first embodiment; FIG. 8 is a schematic enlarged bottom view showing a relevant portion of a fixed plate according to a second embodiment of the present disclosure; FIG. 9 is a schematic enlarged bottom view showing a relevant portion of a fixed plate according to a third embodiment of the present disclosure; FIG. 10 is a schematic enlarged bottom view showing a relevant portion of a fixed plate according to a fourth embodiment of the present disclosure; FIG. 11 is a schematic enlarged sectional view showing relevant portions of a fixed plate and a movable plate according to a fifth embodiment of the present disclosure; and FIG. 12 is a schematic enlarged sectional view showing relevant portions of a fixed plate and a movable plate according to a fuel injection valve in the related art.The present disclosure will be explained below with reference to several embodiments in which a fuel injection valve is applied to an internal combustion engine (hereinafter, engine) mounted in a vehicle. The engine is, for example, a compression ignition type engine such as a diesel engine in each embodiment. The same reference numerals are assigned to the same or similar portions and / or structures throughout the embodiments to avoid repeated explanations.(First Embodiment)A fuel injection valve 1 shown in FIG. 1 is operated by a drive current output from an electric control unit 2 (hereinafter referred to as ECU 2). The ECU 2 calculates a target injection amount based on an engine load, an engine speed, etc. The ECU 2 calculates an injection period corresponding to the target injection amount depending on a pressure of the high-pressure fuel to be supplied to the fuel injection valve 1. The ECU 2 calculates a power supply time depending on the above-mentioned calculated injection time, taking into account a delay time for starting fuel injection and a delay time for ending fuel injection. Thereafter, the drive current is supplied to the fuel injection valve 1 during the power supply period.The fuel injection valve 1 is composed of a holder 10 made of metal, a fixed plate 20, and a nozzle body 30, and the fixed plate 20 and the nozzle body 30 are joined to the holder 10 by a retaining nut 40. Hereinafter, the holder 10, the fixed plate 20, and the nozzle body 30 are collectively referred to as an injection body.A needle 50 (a valve body) is movably accommodated in the nozzle body 30. At a front end of the nozzle body 30, injection ports 32 are formed to inject a high-pressure fuel. When a valve body surface 52 formed in the valve body 50 is separated from a valve seat surface 33 formed in the nozzle body 30, the injection ports 32 are opened so that the fuel is injected. On the other hand, the injection ports 32 are closed, so that the fuel injection is ended when the valve body 50 seats on the valve seat surface 33.High-pressure liquid paths 11, 21, 31 and 51 are formed in the injection body (10, 20, 30) to introduce the high-pressure fuel into the injection ports 32. The high-pressure fuel is supplied to the fuel injection valve 1 from external components (not shown), i.e., from a bus bar (a pressure accumulation device). The high-pressure liquid paths 11, 21, 31, and 51 are formed in each of the holder 10, the fixed plate 20, and the nozzle body 30. The high-pressure liquid path 51 is a liquid path formed between the nozzle body 30 and the valve body 50.An electric actuator 60 having a solenoid coil 61 or a piezoelectric element is provided in the holder 10. The electric actuator 60 shown in FIG. 1 includes the solenoid coil 61, a plunger 62, a control valve 63, and a spring SP 1. When the drive current is supplied to the solenoid coil 61 to generate an electromagnetic force, the plunger 62 is attracted by the electromagnetic force, and the control valve 63 is moved to a control valve open position (as shown in FIGS. 7A and 7B ). When the power supply to the solenoid coil 61 is cut off, the plunger 62 is pushed down by a spring force of the spring SP 1, so that the control valve 63 is moved to a control valve closing position.As shown in FIG. 2, a cylindrical member 70 is fixed to a lower end surface of the fixed plate ( 20). An upper end portion of the valve body 50 is movably inserted into the cylindrical member 70 so that the valve body 50 can be moved in an upward direction and in a downward direction. The upward direction is an axial direction of the fuel injection valve 1 toward an opposite side of the injection ports 32, whereas the downward direction is the axial direction of the fuel injection valve 1 toward the injection ports 32.A space surrounded by the inner circumferential wall of the cylindrical member 70, the lower end surface of the fixed plate 20, and an upper end surface of the valve body 50 forms a pressure control chamber 71. a high pressure passage 22 for supplying the high-pressure fuel into the pressure control chamber 71 and a low pressure passage 23 for discharging the fuel from the pressure chamber 71 are each formed in the fixed plate 20. A orifice 23a is formed on a side downstream of the low pressure passage 23. An outlet port of the low pressure passage 23 is opened or closed by the control valve 63. The high pressure passage 22 forks into the high pressure liquid paths 11 and 21, and a port 22a is formed at a downstream side of the high pressure passage 22.As shown in FIG. 3, a movable plate 80 having a disc shape is movably accommodated in the pressure control chamber 71 so that the movable plate 80 is movable in the up-and-down direction. A protrusion 82 in a ring shape protruding in the upward direction is formed on an upper end surface of the movable plate 80. When an upper end surface of the protrusion 82 is brought into contact with the lower end surface of the fixed plate 20, a high-pressure port 22 b(which is an outlet port of the high-pressure passage 22) is closed by the protrusion 82. FIG. 3 shows a state of the movable plate 80 being separated from the lower end surface of the fixed plate 20 and the high-pressure port 22 bbeing thereby opened.A through hole 81 is formed in the movable plate 80 to communicate a low pressure port 23 c(which is an inlet port of the low pressure passage 23) and the pressure control chamber 71 with each other. A mouth 81 ais formed at a side downstream of the through hole 81 (at an upper side of the movable plate 80). According to the above-mentioned structure, the pressure control chamber 71 continuously communicates with the low pressure passage 23 even when the movable plate 80 is brought into contact with the fixed plate 20 to close the high pressure port 22 b.As shown in FIG. 4, the low pressure port 23 cis formed in a ring shape at a center of the lower end surface of the fixed plate 20. The high pressure port 22 bformed on a downstream side of the orifice 22 ais formed in a ring shape on a lower end surface of the fixed plate 20 so as to surround the low pressure port 23 c. Further, as shown in FIGS. 3 and 4, an annular recessed portion 24 is formed on the lower end surface of the fixed plate 20 so as to surround the high-pressure port 22 b. A gap 72 formed between an outer circumferential wall of the movable plate 80 and an inner circumferential wall of the cylindrical member 70 performs a function of a fuel passage, so that the high-pressure fuel in the high-pressure passage 22 flows into the pressure control chamber 71 through the gap 72. When the movable plate 80 moves in the downward direction to open the high-pressure port 22 b, the high-pressure fuel flows from the high-pressure passage 22 into the pressure control chamber 71 via the annular recess portion 24 and the gap 72, as indicated by arrows Y in FIG. 3.As shown in FIG. 5, a portion of the lower end surface of the fixed plate 20 (a contact surface) for partitioning the high-pressure port 22 bfrom the low-pressure port 23 cis referred to as a first wall portion 25. Another portion of the lower end surface of the fixed plate 20 for partitioning the annular groove portion 24 from the high pressure port 22 bis referred to as a second wall portion 26. As shown in FIG. 4, each of the first and second wall portions 25 and 26 extends in a ring shape along the high-pressure port 22 b. Lower end surfaces of the first wall portion 25 are referred to as first contact surfaces 25 aand 25 b, whereas lower end surfaces of the second wall portion 26 are referred to as second contact surfaces 26 aand 26 b. The first and second contact surfaces 25 a, 25 b, 26 aand 26 b, among the lower end surfaces of the fixed plate 20, are brought into contact with the upper end surface of the movable plate 80. In other words, from the first and second contact surfaces 25 a, 25 b, 26 a, and 26 b, a pressing force is received by the movable plate 80 on the fixed plate 20.An outer diameter D 1 of the protrusion 82 is made larger than the outer diameter of the second wall portion 26, so that an outer peripheral portion of the protrusion 82 is inside an area of the annular recess portion 24, even when the movable plate 80 is displaced inside the gap 72 in a radial direction of the fuel injection valve 1 (in a horizontal direction in FIG. 5 ).As shown in FIGS. 5 and 6, a first annular groove 25 bis formed on the lower end surface of the first wall portion 25, the first annular groove 25 mbeing recessed in a direction away from the movable plate 80. Similarly, a second annular groove 26 mis formed on the lower end surface of the second wall portion 26, the second annular groove 26 mbeing recessed in the direction away from the movable plate 80. As shown in FIG. 4, each of the first and second grooves 25 mand 26 mextends in a ring shape along the first and second wall portions 25 and 26, respectively. as described above, the lower end surface of the first wall portion 25 is divided into two contact surfaces by the first annular groove 25 m, that is, the first contact surface 25 is on a side closer to the high pressure port 22 band the other first contact surface 25 bis on a side closer to the low pressure port 23 c. Similarly, the lower end surface of the second wall portion 26 is divided into two contact surfaces by the second annular groove 26 m, that is, the second contact surface 26 ais located on a side closer to the high pressure port 22 band the other second contact surface 26 bis located on a side closer to the annular recess portion 24.A portion of the upper end surface of the movable plate 80 that is brought into contact with the first contact surfaces 25 aand 25 bto thereby seal the contact regions is referred to as a first sealing surface 82 a. Another portion of the upper end surface of the movable plate 80 that is brought into contact with the second contact surfaces 26 aand 26 bto thereby seal the contact portions is referred to as a second sealing surface 82 b.As shown in FIGS. 5 and 6, a first communication groove 25 nis formed on the lower end surface of the first wall portion 25 (i.e., the first contact surface 25 b) so that the first annular groove 25 mand the low pressure passage 23 care in contact with each other. Similarly, a second communication groove 26 nis formed on the lower end surface of the second wall portion 26 (i.e., the second contact surface 26 b) so that the second annular groove 26 mand the annular recess portion 24 are in contact with each other. Thus, each of the first contact surface 25 aand the second contact surface 26 a, both formed on the sides closer to the high-pressure port 22 b, is formed as a full ring shape extending along the high-pressure port 22 b. On the other hand, each of the first contact surface 25 band the second contact surface 26 bformed on the sides opposite to the high-pressure terminal 22 bis partitioned by the first and second communication grooves 25 nand 26 n.According to the above-mentioned configuration, among the lower end surfaces of the first wall portion 25, only the first contact surface 25 aon which the first communication groove 25 nis not formed performs the sealing function, whereas the first contact surface 25 bon the opposite side of the high pressure terminal 22 bhas no sealing function. Similarly, among the lower end surfaces of the second wall portion 26, only the second contact surface 26 aon which the communication groove 26 nis not formed performs the sealing function, whereas the second contact surface 26 bon the opposite side of the high pressure port 22 bhas no sealing function.As described above, in a state (in a state of plate contact) in which the movable plate 80 is in contact with the fixed plate 20, that is, a state in which the first and second sealing surfaces 82 aand 82 bare in contact with the contact surfaces 25 a, 25 b, 26 a, and 26 b, the high-pressure terminal 22 bis closed by the first and second contact surfaces 25 aand 26 a. In the above state, the communication groove 25 nand the first annular groove 25 mare filled with the low pressure fuel of the low pressure port 23 c, whereas the second communication groove 26 nand the second annular groove 26 mare filled with the fuel of the annular recess portion 24 filled with the controlled pressure fuel.In FIG. 3, "P1" is a pressure in the high pressure passage 22, "P2" is a pressure in the pressure control chamber 71, and "P3" is a pressure in the low pressure passage 23, while "P1" > "P2" > "P3".In addition, in FIG. 3, "F 1" is a force that receives the upper end surface and the movable plate 80 by the pressure "P 3" of the low pressure port 23 cin the plate contact state (in which the movable plate 80 is in contact with the fixed plate 20). "F 2" is a force that is received from the upper end surface of the movable plate 80 by the pressure "P 1" of the high pressure port 22 bin the plate contact state. "F 3" is a force that is received from the upper end surface of the movable plate 80 (the outer circumferential end surface of the movable plate 80 outside the second wall portion 26) by the pressure "P 2" of the pressure control chamber 71. "F 4" is a force, which is received from the lower end surface of the movable plate 80 by the pressure "P 2" of the pressure control chamber 71.Therefore, when a total force of "F1", "F2", and "F3" in the plate contact state is smaller than the force "F4", a force "F" in the upward direction is applied to the movable plate 80 so that the plate contact state is maintained. On the other hand, when the total force of "F1", "F2", and "F3" is larger than "F4+Flink", that is, (F1+F2+F3)>(F4+Flink), the movable plate 80 is separated from the fixed plate 20. "Flink" is a bonding force generated between the first contact surfaces 25 aand 25 band the first sealing surface 82 aand between the second contact surfaces 26 aand 26 band the second sealing surface 82 b.More specifically, in the plate contact state (with the movable plate 80 in contact with the fixed plate 20 and the valve body 50 opening the injection ports 32), the total force of "F1+F2+F3" becomes larger than the force of "F4+Flink" when the control valve 63 is closed, thereby increasing the control pressure "P2" and the low pressure "P3.". Thereafter, the movable plate 80 is separated from the fixed plate 20. The high pressure fuel "P1" flows from the high pressure port 22b through the gap 72 into the pressure control chamber 71, and the control pressure "P2" in the pressure control chamber 71 is thereby rapidly increased. As a result, the valve body 50 is pressed onto the valve seat surface 33 by the control pressure "P 2" to close the injection ports 32 (the valve body 50 is moved in the valve body closing direction).An operation of fuel injection in response to the drive current to the fuel injection valve 1 from the ECU 2 will be described with reference to FIGS. 7A to 7F.When the drive current is supplied from the ECU 2 to the solenoid coil 61 at a time "t 1" to open the control valve 63, the low pressure passage 23 is connected to a low pressure liquid path 12 (FIG. 2 ), so that fuel in the pressure control chamber 71 starts to be discharged to an outside of the fuel injection valve 1 via the low pressure passage 23 and the low pressure liquid path 12. The fuel discharge lowers the fuel pressure in a space between the upper end surface of the movable plate 80 and the lower end surface of the fixed plate 20 (i.e., the fuel pressure at the low pressure port 23 c). The movable plate 80 starts its upward movement in response to the lowering of the fuel pressure, and the movable plate 80 is brought into contact with the fixed plate 20 at a time "t2". More specifically, the movable plate 80 closes the high pressure port 22 bto thereby shut off the communication between the high pressure passage 22 and the pressure control chamber 71.Thereafter, the fuel pressure in the pressure control chamber 71 is rapidly lowered, so that the valve body 50 is raised at a high speed in a direction toward the pressure control chamber 71. In other words, the valve body 50 starts its upward movement (displacement) at a time "t3.". During a period ("t3"-"t5") in which the valve body 50 is displaced, the fuel pressure in the pressure control chamber 71 is maintained at an approximately constant value due to a decrease in the volume of the pressure control chamber 71.When the power supply of the drive current is thereafter cut off by the ECU 2 to start a control valve closing movement of the control valve 63 at a time "t 4", the fuel discharge through the low pressure passage 23 is stopped. The completion of the fuel discharge first increases the fuel pressure in the space between the upper end surface of the movable plate 80 and the lower end surface of the fixed plate 20 (i.e., the fuel pressure in the low pressure port 23 c). At this time, the force "F 1" is increased, so that the total force "F 1+F 2+F 3" for pressing down the movable plate 80 is increased.Accordingly, the total force "F 1+F 2+F 3" becomes larger than the force "F 4+Flink", i.e., (F 1+F 2+F 3)>(F 4+Flink), the movable plate 80 that has been in the state of plate contact is separated from the fixed plate 20 at a time "t 5". More specifically, the movable plate 80 opens the high pressure port 22 bto thereby connect the high pressure passage 22 to the pressure control chamber 71. Thereafter, the fuel pressure in the pressure control chamber 71 is rapidly increased to push down the valve body 50 at a high speed. The valve body 50 seats on the valve seat surface 33 at a time "t 6", which corresponds to the valve body closing condition.According to the present embodiment, the first annular groove 25 mis formed on the lower end surface of the first wall portion 25, the first wall portion 25 partitioning the high pressure port 22 band the low pressure port 22 cfrom each other, and the first annular groove 25 mis retained the fuel together with the movable plate 80 that is in contact with the fixed plate 20. Therefore, the binding force "Flink" can be reduced when the first sealing surface 82 aof the movable plate 80 is separated from the lower end surface of the first wall portion 25 (i.e., the first contact surfaces 25 aand 25 b). More specifically, the fuel flows from the high-pressure port 22 binto a space between the first sealing surface 82 aand the first contact surface 25 aas indicated by an arrow A in FIG. 6. Similarly, the fuel flows out of the low pressure port 23 cin a space between the first sealing surface 82 aand the other first contact surface 25 bas indicated by an arrow B in FIG. 6. In addition, the fuel flows from the first annular groove 25 minto the respective spaces indicated by arrows C and D in FIG. 6. As a result, the binding force generated between the movable plate 80 and the fixed plate 20 can be reduced.Further, according to the present embodiment, the second annular groove 26 mmay be formed on the lower end surface of the second wall portion 26, the second wall portion 26 separating the high pressure port 22 band the annular recess portion 24 from each other, and the second annular groove 26 mretains the fuel together with the movable plate 80 that is in contact with the fixed plate 20. Therefore, the binding force can be reduced when the second sealing surface 82 bof the movable plate 80 is separated from the lower end surface of the second wall portion 26 (i.e., the second contact surfaces 26 aand 26 b). More specifically, the fuel flows from the high-pressure port 22 binto a space between the second sealing surface 22 band the second contact surface 26 aas indicated by an arrow E in FIG. 6. Similarly, the fuel flows from the annular recess portion 24 into a space between the second sealing surface 82 band the second contact surface 26 bas indicated by an arrow F in FIG. 6. In addition, the fuel flows from the second annular groove 26 minto the respective spaces as indicated by arrows G and H in FIG. 6. As a result, the bonding force generated between the movable plate 80 and the fixed plate 20 is reduced.As described above, it is possible to prevent the time (the time "t 5" in FIG. 7D ) of the movement of the movable plate 80 (i.e., the movable plate 80 is separated from the fixed plate 20 to open the high-pressure port 22 b) from being delayed due to the binding force. In other words, it is possible to prevent the function of the valve body 50 (i.e., a response characteristic of the valve body 50 that moves to a valve body closing position by an increase in the fuel pressure in the pressure control chamber 71) from degrading. Accordingly, it is possible to prevent the fuel injection period from becoming longer with respect to the power supply period. That is, it is possible to prevent an actual fuel injection amount from becoming larger than a target amount.In addition, since the binding force can be reduced as described above, it is possible to suppress generation of deviations with respect to timings for opening the high-pressure port 22 b. Therefore, it is possible to suppress generation of deviations in timings for closing the valve body 50 by an increase in the back pressure of the valve body 50. A variation of the fuel injection amount can be decreased.The present embodiment provides the following advantages with respect to the following features:(1) First Feature and Advantage:According to the present embodiment, the first connection groove 25 nis formed on the first contact surface 25 bto connect the first annular groove 25 mto the low pressure port 23 cin the plate contact state (in which the movable plate 80 is in contact with the fixed plate 20).When the movable plate is separated from the fixed plate 20, the fuel flows from the first annular groove 25 minto the spaces between the first contact surfaces 25 aand 25 band the first sealing surface 82 a. In the above-mentioned operation, the fuel flows from the low-pressure port 23 cin the first annular groove 25 nthrough the first communication groove 25 n. It is therefore possible to avoid a situation in which a negative pressure is generated in the first communication groove 25 nat a moment when the movable plate 80 is to be separated from the fixed plate 20. At this time, it is possible to facilitate a flow of the fuel into the spaces between the first contact surfaces 25 aand 25 band the first sealing surface 82 a. Thus, the binding force can be further reduced.Moreover, according to the present embodiment, the second communication groove 26 nis formed on the second contact surface 26 bto connect the second annular groove 26 mto the annular recess portion 24 in the state of plate contact.When the movable plate 80 is separated from the fixed plate 20, the fuel flows from the second annular groove 26 ninto the spaces between the second contact surfaces 26 aand 26 band the second sealing surface 82 b. In the above-mentioned operation, the fuel flows from the annular groove portion 24 to the second annular groove 26 mthrough the second communication groove 26 n. Therefore, it is possible to avoid a situation in which a negative pressure is generated in the second communication groove 26 nat the moment when the movable plate 80 is to be separated from the fixed plate 20. Thereby, it is possible to facilitate a flow of the fuel into the spaces between the second contact surfaces 26 aand 26 band the second sealing surface 82 b. Thus, the binding force can be further reduced.(2) Second Feature and Advantage:According to the present embodiment, the first communication groove 25 nconnects the first annular groove 25 mto the low pressure port 23 cout of the high pressure port 23 band the low pressure port 23 c. On the other hand, the second communication groove 26 nconnects the second annular groove 26 mto the annular recess portion 24 from the high pressure port 22 band the annular recess portion 24.In contrast to the above-mentioned feature, if the first and second annular grooves 25m and 26m are connected to the high-pressure port 22b, surfaces of the first and second annular grooves 25m and 26m also belong to such a surface of the movable plate 80 that receives the high pressure "P1" when the high-pressure port 22b is closed by the movable plate 80. Thereafter, the force "F 2" in FIG. 3 is increased. As a result, the pressing force "F=F4 - (F1+F2+F3)" of the movable plate 80 on the fixed plate 20 becomes smaller. It may be problematic that a probability of securely closing the high-pressure port 22 bsides.However, according to the above feature of the present invention, each of the first and second annular grooves 25m and 26m is connected to the opposite side of the high pressure port 22b, respectively (i.e., the low pressure port 23c and the annular groove portion 24). Therefore, it is possible to suppress an increase in the area of the movable high pressure receiving plate 80 "P 1.". More specifically, it is possible to obtain the sufficient amount of the pressing force "F" of the movable plate 80 to overcome the above-mentioned possible problem.(3) Third feature and advantage:According to the present embodiment, the first annular groove 25 mis formed in the ring shape extending along the first contact surfaces 25 aand 25 band the first sealing surface 82 a, while the second annular groove 26 mis formed similarly in the ring shape extending along the second contact surfaces 26 aand 26 band the second sealing surface 82 b.According to such a configuration, a length of the first and second annular grooves 25 mand 26 mcan be made longer than a case where the first and second grooves 25 mand 26 mhave shapes other than the ring shape. Therefore, it is possible to make larger areas of the respective spaces between the contact surfaces 25 a, 25 b, 26 aand 26 band the seal surfaces 82 aand 82 binto which fuel flows from the grooves 25 mand 26 m. Accordingly, it is possible to facilitate the fuel flowing into the spaces between the contact surfaces and the seal surfaces, thereby further reducing the binding force.(4) Fourth feature and advantage:As will be explained below in connection with a fifth embodiment (FIG. 11 ) of the present disclosure, the first and second annular grooves 25 mand 26 mmay be formed on the upper end surface of the movable plate 80 instead of the lower end surface of the fixed plate 20 (first embodiment). In the fifth embodiment (FIG. 11 ), the first and second annular grooves are denoted by 82 aand 82 bm. In such an embodiment, it is necessary to decide the dimensions of related components so that the annular grooves 82 aand 82 bmare not displaced from the lower end surface of the wall portions 25 and 26 even when the movable plate 80 is displaced in the radial direction of the fuel injection valve (i.e., in the horizontal direction in the drawing of FIG. 11 ).However, according to the present embodiment, the first and second annular grooves 25 mand 26 mare formed on the lower end surface of the fixed plate 20. Therefore, compared with the above-explained modifications (corresponding to the fifth embodiment explained below), the present embodiment is more advantageous because the first and second annular grooves 25m and 26m are not displaced from the sealing surfaces 82a and 82b formed on the upper end surface of the movable plate 80.(Second Embodiment)As described above and shown in FIG. 6, in the first embodiment, in the state of plate contact, the first communication groove 25 nconnects the first annular groove 25 mto the low pressure port 23 c, while the second communication groove 26 nconnects the second annular groove 26 mto the annular recess portion 24. According to a second embodiment of the present disclosure shown in FIG. 8, the first communication groove 25 nconnects the first annular groove 25 mto the high pressure port 22 b, and the second communication groove 26 nconnects the second annular groove 26 mto the high pressure port 22 bas well.It is also possible to combine the first embodiment shown in FIG. 6 and the second embodiment shown in FIG. 8. For example, the first communication groove 25 nconnects the first annular groove 25 mto the low pressure port 23 c, while the second communication groove 26 nconnects the second annular groove 26 mto the high pressure port 22 b. Otherwise, the first communication groove 25 nconnects the first annular groove 25 mto the high pressure port 22 b, while the second communication groove 26 nconnects the second annular groove 26 mto the annular recessed portion 24.(Third Embodiment)In the above-mentioned first and second embodiments, the communication grooves 25 nand 26 nare each formed such that neither the first contact surface 25 bon which the first communication groove 25 nis formed nor the second contact surface 26 bon which the second communication groove 26 nis formed performs the sealing function.However, according to a third embodiment, the communication grooves 25 nand 26 nare removed as shown in FIG. 9. Accordingly, each of the first contact surfaces 25 aand 25 band each of the second contact surfaces 26 aand 26 btakes the sealing function.(Fourth Embodiment)In the above-mentioned embodiments, each of the grooves 25m and 26m is formed in the ring shape. According to a fourth embodiment shown in FIG. 10, a plurality of non-annular first grooves 25 mare formed on a first contact surface 25 clocated on a lower end surface of the first wall portion 25. Similarly, a plurality of non-annular second grooves 26 mare formed on a second contact surface 26 cwhich is located on a lower end surface of the second wall portion 26. In the same manner as in the third embodiment, the communication grooves 25n and 26n in the fourth embodiment are removed.(Fifth Embodiment)In the above embodiments, the first annular or non-annular grooves 25m and the second annular or non-annular grooves 26m are formed on the lower end surface of the fixed plate 20. According to a fifth embodiment, a first annular groove 82 amand a second annular groove 82 bmare formed on the upper end surface of the movable plate 80 as shown in FIG. 11.More specifically, a portion of the upper end surface of the movable plate 80 that is opposed to the lower end surface 25 c(the first contact surface) of the first wall portion 25 corresponds to the first sealing surface 82 a. The first annular groove 82 amis formed on the first sealing surface 82 a. Similarly, a portion of the upper end surface of the movable plate 80 that is opposed to the lower end surface 26 c(the second contact surface) of the second wall portion 26 is the second sealing surface 82 b. The second annular groove 82 bmis formed on the second sealing surface 82 b.(Other Embodiments and / or Modifications)The present disclosure should not be limited to the above embodiments, but may be modified in various ways as described below. In addition, the features of the respective embodiments can optionally be combined with one another.(M 1) In the above-mentioned embodiments, the second wall portion 26 is formed on the lower end surface of the fixed plate 20 so as to separate the high-pressure port 22 band the annular groove portion 24 from each other in the state of plate contact. However, the second wall portion 26 may be removed. In other words, the contact surfaces 26 a, 26 b, and 26 cand the second sealing surface 82 bmay be removed. Otherwise, in a modification in which the second contact surfaces and the second seal surface are formed, the second grooves 26 mand 82 bmmay be removed.(M2) In the fourth embodiment (FIG. 10 ), a plurality of non-annular grooves 25 mand 26 mare formed on the respective contact surfaces 25 cand 26 c. This may be modified so that a part of a surface for the lower end surfaces of the first and second wall portions 25 and 26 is made as a rough surface during a surface treatment process. And such rough surface portions can be used as the grooves 25m and 26m.(M 3) In the first to third embodiments, an annular groove 25 mor 26 mis formed on each of the first and second wall portions 25 and 26. On the lower end surface of the first and / or the second wall portion, a plurality of annular grooves may be formed.(M4) In the above-mentioned embodiments, the displacement of the movable plate 80 in the vertical direction (upward and downward direction) depends on the balance among the forces "F1", "F2", "F3", and "F4" generated by the fuel pressure. A spring may be provided to apply a spring force to the movable plate 80. For example, the spring force may be applied to the movable plate 80 in a direction toward the fixed plate 20.

Claims

A fuel injection valve, comprising: a valve body (50) movably accommodated in a nozzle body (30) to open or close an injection port (32); a pressure control chamber (71) for applying a fuel pressure to the valve body (50) in a valve body closing direction; a fixed plate (20) having a high pressure passage (22) for supplying a fuel under high pressure to the pressure control chamber (71) so as to move the valve body (50) in the valve body closing direction, and the fixed plate (20) having a low pressure passage (23) for discharging fuel from the pressure control chamber (71) so as to move the valve body in a valve body opening direction, and the fixed plate (20) having a lower end surface (25a, 25b, 26a, 26b) at which a high pressure port (22b) connected to the high pressure passage (22) and a low pressure port (23c) connected to the low pressure passage (23) are formed such that the high pressure port (22b) surrounds the low pressure port (23c); and a movable plate (80), which is movably accommodated in the pressure control chamber (71), the movable plate (80) being brought into contact with the lower end surface (25a, 25b, 26a, 26b) of the fixed plate (20) when the fuel is discharged from the pressure control chamber (71) so as to close the high pressure port (22b), and the movable plate (80) being separated from the lower end surface (25a, 25b, 26a, 26b) of the fixed plate (20) when the high pressure fuel is supplied to the pressure control chamber (71) so as to open the high pressure port (22b), the lower end surface having a first wall portion (25) which surrounds the low pressure port (23c) and is formed between the low pressure port (23c) and the high pressure port (22b), wherein the first wall portion (25) has a first contact surface (25a, 25b) for separating the high-pressure port (22b) from the low-pressure port (23c) in a plate contact state where the movable plate (80) is in contact with the fixed plate (20), the lower end surface having a second wall portion (26) surrounding the high-pressure port (22b) and formed on an outer side of the high-pressure port (22b), the second wall portion (26) having a second contact surface (26a, 26b) for separating the high-pressure port (22b) from the outer side of the high-pressure port (22b) in the plate contact state, the movable plate (80) having a first sealing surface (82a), to seal a space between the first contact surface (25a, 25b) and the first sealing surface (82a) in the plate contact state, and the movable plate (80) has a second sealing surface (82b) to seal a space between the second contact surface (26a, 26b) and the second sealing surface (82b) in the plate contact state, and wherein a first groove (25m) is formed as a binding force reducing groove on the first contact surface (25a, 25b) to receive a part of the fuel when the movable plate (80) is brought into contact with the fixed plate (20), and a second groove (26m) is formed as a binding force reducing groove on the second contact surface (26a, 26b), In order to receive another part of the fuel when the movable plate (80) is brought into contact with the fixed plate (20), so that a binding force generated between the movable plate (80) and the fixed plate (20) is reduced when the movable plate (80) is separated from the fixed plate (20).A fuel injection valve, comprising: a valve body (50) movably accommodated in a nozzle body (30) to open or close an injection port (32); a pressure control chamber (71) for applying a fuel pressure to the valve body (50) in a valve body closing direction; a fixed plate (20) having a high pressure passage (22) for supplying a fuel under high pressure to the pressure control chamber (71) so as to move the valve body (50) in the valve body closing direction, and the fixed plate (20) having a low pressure passage (23) for discharging fuel from the pressure control chamber (71) so as to move the valve body in a valve body opening direction, and the fixed plate (20) having a lower end surface (25c, 26c) on which a high pressure port (22b) connected to the high pressure passage (22) and a low pressure port (23c) connected to the low pressure passage (23) are formed such that the high pressure port (22b) surrounds the low pressure port (23c); and a movable plate (80), which is movably accommodated in the pressure control chamber (71), the movable plate (80) being brought into contact with the lower end surface (25c, 26c) of the fixed plate (20) when the fuel is discharged from the pressure control chamber (71) so as to close the high pressure port (22b), and the movable plate (80) being separated from the lower end surface (25c, 26c) of the fixed plate (20) when the high pressure fuel is supplied to the pressure control chamber (71) so as to open the high pressure port (22b), the lower end surface having a first wall portion (25) which surrounds the low pressure port (23c) and is formed between the low pressure port (23c) and the high pressure port (22b), the first wall portion (25) having a first contact surface (25c), to separate the high-pressure terminal (22b) from the low-pressure terminal (23c) in a plate contact state in which the movable plate (80) is in contact with the fixed plate (20), the lower end surface having a second wall portion (26) surrounding the high-pressure terminal (22b) and formed on an outer side of the high-pressure terminal (22b), the second wall portion (26) having a second contact surface (26c) to separate the high-pressure terminal (22b) from the outer side of the high-pressure terminal (22b) in the plate contact state, the movable plate (80) having a first sealing surface (82a) facing the first contact surface (25c) of the first wall portion (25), to seal a space between the first contact surface (25c) and the first sealing surface (82a) in the plate contact state, and the movable plate (80) has a second sealing surface (82b) that faces the second contact surface (26c) of the second wall portion (26) to seal a space between the second contact surface (26c) and the second sealing surface (82b) in the plate contact state, and wherein a first groove (82am) is formed as a bonding force reducing groove on the first sealing surface (82a) to receive a part of the fuel when the movable plate (80) is brought into contact with the fixed plate (20), and a second groove (82bm) as a binding force reducing groove is formed on the second sealing surface (82b) to receive another part of the fuel when the movable plate (80) is brought into contact with the fixed plate (20), so that a binding force generated between the movable plate (80) and the fixed plate (20) is reduced when the movable plate (80) is separated from the fixed plate (20).The fuel injection valve according to claim 1 or 2, wherein a first communication groove (25n) is formed on the first contact surface (25a, 25b, 25c) or on the first sealing surface (82a) to connect the first groove (25m, 82am) to the high pressure port (22b) or the low pressure port (23c) in the state of plate contact.The fuel injection valve according to claim 3, wherein the first communication groove (25n) connects the first groove (25m, 82am) to the low pressure port (23c) in the state of plate contact.The fuel injection valve according to any one of claims 1 to 4, wherein the high pressure port (22b) is annularly formed so as to surround the low pressure port (23c), each of the first contact surface (25a, 25b) and the first sealing surface (82a) is annularly formed between the high pressure port (22b) and the low pressure port (23c), and the first groove (25m, 82am) is annularly formed and extends along the first contact surface (25a, 25b) and the first sealing surface (82a).The fuel injection valve according to any one of claims 1 to 5, wherein a recessed portion (24) is formed in the lower end surface of the fixed plate (20) on a side of the high pressure port (22b) opposite to the low pressure portion (23c).The fuel injection valve according to claim 6, wherein a second communication groove (26n) is formed on the second contact surface (26a, 26b, 26c) or the second sealing surface (82b) to connect the second groove (26m, 82bm) to the high pressure port (22b) or the recessed portion (24) in the state of plate contact.The fuel injection valve according to claim 7, wherein the second communication groove 26n connects the second groove (26m, 82bm) to the recessed portion 24 in the plate contact state.The fuel injection valve according to any one of claims 6 to 8, wherein the high pressure port (22b) is annularly formed so as to surround the low pressure port (23c), the recess portion 24 is annularly formed so as to surround the high pressure port 22b, each of the second contact surface (26a, 26b) and the second sealing surface (82b) is annularly formed between the high pressure port (22b) and the recess portion (24), and the second groove (26m, 82bm) is annularly formed and extends along the second contact surface (26a, 26b) and the second sealing surface (82b).

Images