Injector

Abstract

To close a pressure control chamber securely when electricity transmission to an injector ends to prevent deterioration of fuel consumption of an internal combustion engine.SOLUTION: An injector includes: an electromagnet which attracts an armature when energized; a valve spring which presses the armature in a direction away from the electromagnet; a valve body having a pressure control chamber which presses a nozzle needle in a direction such that the nozzle needle closes a fuel injection hole; a valve ball 67 which may close the pressure control chamber by a pressing force of the valve spring; and a ball holder 68 disposed between the armature and the valve ball 67. The ball holder 68 includes rotational force generation parts 90 for rotating the ball holder 68 around a center axis Z of the ball holder 68 by flow of a fuel flowing out from the pressure control chamber when the electromagnet is energized.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an injector that injects fuel into a combustion chamber of an internal combustion engine.

Background Art

[0002] Conventionally, a direct injection type internal combustion engine equipped with an injector that directly injects fuel into a combustion chamber of an internal combustion engine is known. In particular, when the direct injection type internal combustion engine is a diesel engine, a common rail fuel injection control device is widely used.

[0003] The common rail fuel injection control device includes a low-pressure pump that supplies fuel in a fuel tank to a high-pressure pump, a high-pressure pump that pumps the fuel supplied from the low-pressure pump to a common rail, a common rail that accumulates the high-pressure fuel pumped from the high-pressure pump, an injector that injects the high-pressure fuel supplied from the common rail into a combustion chamber of an internal combustion engine, and a control device that receives outputs of various sensors and controls the common rail fuel injection control device.

[0004] The injector used in the common rail fuel injection control device includes a nozzle having a fuel injection hole for injecting fuel, a nozzle needle for opening and closing the fuel injection hole, a pressure control chamber for controlling a back pressure that presses the nozzle needle in a closing direction of the fuel injection hole, and a back pressure control unit for controlling an outflow of fuel in the pressure control chamber. The back pressure control unit closes an opening / closing orifice provided in the pressure control chamber, thereby seating the nozzle needle on a seat surface of the nozzle and closing the fuel injection hole. On the other hand, the back pressure control unit opens the opening / closing orifice to leak a part of the fuel in the pressure control chamber, thereby disengaging the nozzle needle from the seat surface of the nozzle and injecting fuel from the fuel injection hole. (See Patent Document 1)

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] The injector's back pressure control unit comprises an electromagnetic actuator that reciprocates the armature, a valve ball that closes the orifice for opening and closing the pressure control chamber when the power supply to the electromagnet of the electromagnetic actuator is stopped, and a ball holder positioned between the armature and the valve ball to hold the valve ball.

[0007] When the electromagnet is de-energized, the valve ball closes the opening orifice due to the biasing force of the valve spring, which biases the armature toward the opening orifice, received via the armature and ball holder. On the other hand, when the electromagnet is energized, the armature is attracted toward the opposite side of the opening orifice, causing the valve ball and ball holder to rise due to the fuel pressure in the pressure control chamber, and the opening orifice opens.

[0008] When the opening orifice is opened, the valve ball and ball holder may be slightly displaced radially in the axial view of the injector due to the influence of the fuel flow out of the opening orifice. Even in this case, since the seat surface on which the valve ball sits is formed such that its inner diameter expands from the opening orifice side toward the armature side, the valve ball is able to move across the seat surface when it sits on it, and the valve ball and ball holder return to the radial center of the seat surface.

[0009] However, if the frictional force between the armature and the ball holder becomes greater than usual, for example, if fine particles contained in the fuel become trapped in the area where the armature and the ball holder are in contact, there is a risk that the valve ball may not seat in the radial center of the seat surface after the electromagnet is de-energized. This phenomenon will be described in detail below.

[0010] When the valve ball lifts off the seat surface, the armature moves away from the seat surface, while the valve ball and ball holder are subjected to the pressure of the fuel flowing out of the pressure control chamber. On the other hand, when the valve ball sits on the seat surface, the armature moves towards the seat surface, while the valve ball and ball holder are subjected to the pressure of the fuel flowing out of the pressure control chamber. Therefore, the pressing force at the contact surface between the armature and the ball holder is greater when the valve ball sits on than when it lifts off. Consequently, the frictional force between the armature and the ball holder is greater when the valve ball sits on than when it lifts off.

[0011] Furthermore, if the frictional force between the armature and the ball holder increases due to the effects of the particles mentioned above, when the valve ball lifts off the seat surface, the valve ball and the ball holder are displaced radially. However, when the valve ball sits back on the seat surface, the radial displacement of the ball holder relative to the armature may be hindered or insufficient, potentially preventing the valve ball from returning completely to the radial center of the seat surface.

[0012] If the valve ball cannot seat at the radial center of the seat surface when the opening / closing orifice is closed, fuel will leak from the pressure control chamber to the upper part of the seat, even though the electromagnet is not energized. This will cause the discharge rate of the high-pressure pump to increase in order to maintain fuel pressure, negatively impacting the fuel efficiency of the internal combustion engine.

[0013] This invention was made against the backdrop of the above-mentioned problems, and aims to provide an injector in which the valve ball reliably seats at the radial center of the seat portion when the opening and closing orifice is closed. [Means for solving the problem]

[0014] According to the present invention, an injector is provided comprising: an electromagnet that attracts an armature when energized; a valve spring that presses the armature away from the electromagnet; a valve body having a pressure control chamber that presses a nozzle needle in a direction that closes a fuel injection hole; a valve ball capable of closing the pressure control chamber by the pressing force of the valve spring; and a ball holder disposed between the armature and the valve ball, wherein the ball holder is provided with a rotational force generating unit that rotates the ball holder around its central axis due to the flow of fuel flowing out of the pressure control chamber when the electromagnet is energized. [Effects of the Invention]

[0015] According to the injector of the present invention, it is possible to prevent deterioration in fuel efficiency of an internal combustion engine equipped with a pressure-accumulating fuel injection control device. [Brief explanation of the drawing]

[0016] [Figure 1] This diagram shows the overall configuration of the fuel injection control device according to this embodiment. [Figure 2] This is a cross-sectional view of an injector according to an embodiment of the present invention. [Figure 3] This is a partially enlarged view of a cross-sectional view of an injector according to an embodiment of the present invention. [Figure 4] This is a partially enlarged view of a cross-sectional view of an injector according to an embodiment of the present invention. [Figure 5] This figure shows a ball holder 68 according to a first embodiment of the present invention, where Figure 5(a) is a front view and Figure 5(b) is a bottom view. [Figure 6] This figure shows an armature bolt 78 according to a second embodiment of the present invention. [Figure 7] This figure shows a ball holder 68 according to a third embodiment of the present invention, where Figure 7(a) is a front view and Figure 7(b) is a bottom view. [Figure 8] This figure shows an armature bolt 78 according to a fourth embodiment of the present invention.

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with appropriate reference to the drawings. Note that the members, arrangements, etc. described below do not limit the present invention, and various modifications can be made within the scope of the gist of the present invention. Also, in each figure, the same reference numerals are used to indicate the same elements, and the description thereof is appropriately omitted. In addition, in each figure, the illustration of the detailed parts is appropriately simplified or omitted. Also, duplicate descriptions are appropriately simplified or omitted.

[0018] (First Embodiment) The first embodiment of the present invention will be described with appropriate reference to the drawings. FIG. 1 shows the overall configuration of a fuel injection control device according to this embodiment. The fuel injection control device according to this embodiment is a pressure accumulator type fuel injection control device 1. The pressure accumulator type fuel injection control device 1 is a device for injecting fuel into a cylinder of an internal combustion engine (not shown) mounted on a vehicle, and mainly includes a fuel tank 2, a low-pressure pump 11, a fuel filter 12, a high-pressure pump 3, a flow control valve 19, a common rail 5, a pressure control valve 13, an injector 7, an electronic control unit 9 (ECU), etc.

[0019] The low-pressure pump 11 and the high-pressure pump 3 are connected by a low-pressure fuel passage 21, and the high-pressure pump 3 and the common rail 5, and the common rail 5 and the injector 7 are connected by high-pressure fuel passages 23 and 25, respectively. Further, return passages 27, 28, and 29 for returning surplus fuel that is not injected from the injector 7 to the fuel tank 2 are connected to the high-pressure pump 3, the common rail 5, and the injector 7, respectively.

[0020] The low-pressure pump 11 draws up fuel from the fuel tank 2, pressurizes it, and supplies fuel to the high-pressure pump 3 via the low-pressure fuel passage 21. This low-pressure pump 11 is an in-tank type electric pump located inside the fuel tank 2 and is operated by current supplied from a battery. However, the low-pressure pump 11 may be located outside the fuel tank 2, or it may be integrated with the high-pressure pump 3.

[0021] The high-pressure pump 3 is equipped with a flow control valve 19 that communicates with the inlet portion of the low-pressure fuel and adjusts the discharge amount of the high-pressure pump 3. The flow control valve 19 uses an electromagnetic proportional control valve in which the stroke amount of the valve member that opens and closes the fuel passage according to the supply current value is variable, and the area of ​​the fuel passage can be adjusted.

[0022] The high-pressure pump 3 pressurizes the fuel introduced by the low-pressure pump 11 via the flow control valve 19 and pumps it to the common rail 5 via the high-pressure fuel passage 23.

[0023] The common rail 5 stores high-pressure fuel pressurized by the high-pressure pump 3 and supplies fuel to each injector 7 connected via the high-pressure fuel passage 25. A rail pressure sensor 15 and a pressure control valve 13 are attached to the common rail 5.

[0024] The rail pressure sensor 15 detects the fuel pressure (hereinafter also referred to as rail pressure) within the common rail 5. The sensor signal from the rail pressure sensor 15 is sent to the electronic control unit 9.

[0025] The pressure control valve 13 is used to regulate the rail pressure by adjusting the flow rate of high-pressure fuel returned from the common rail 5 to the fuel tank 2. The pressure control valve 13 uses an electromagnetic proportional control valve in which the stroke amount of the valve member for opening and closing the fuel passage is variable according to the supply current value, and the area of ​​the fuel passage can be adjusted. Alternatively, a mechanical safety valve that opens when a predetermined pressure is reached may be used instead of the pressure control valve 13.

[0026] The electronic control unit 9 is centered around a microcomputer of a known configuration and includes memory elements such as RAM and ROM, as well as a drive circuit for driving the injector 7 and a power supply circuit for supplying power to the flow control valve 19 and the pressure control valve 13. In addition, the electronic control unit 9 receives detection signals from the rail pressure sensor 15, as well as various detection signals such as the rotational speed of the internal combustion engine, accelerator opening, and fuel temperature, which are used for controlling the operation of the internal combustion engine and fuel injection.

[0027] The structure of the injector 7 according to this embodiment will be described with reference to Figures 2 to 4. Figure 2 is a cross-sectional view of the injector 7 according to an embodiment of the present invention. Figure 3 is an enlarged view of the part indicated by A in Figure 2. Figure 4 is an enlarged view of the part indicated by B in Figure 3.

[0028] As shown in Figure 2, the injector 7 comprises an injector body 41, a back pressure control unit 70, a valve piston 63, a nozzle 43, a nozzle spring 79, and an inlet connector 45. In the description of the injector 7 in this specification, unless otherwise specified, the nozzle 43 side is considered the lower side, and the opposite side, i.e., the back pressure control unit 70 side, is considered the upper side.

[0029] The injector body 41 has a stepped through-hole 41a that penetrates vertically. The central axis of the through-hole 41a coincides with the central axis of the injector body 41, that is, the central axis of the injector 7. The valve piston 63 is housed in the through-hole 41a so as to be movable vertically. The holder 50, guide member 71, and valve body 49, which will be described later, are also housed in the through-hole 41a.

[0030] Furthermore, a first fuel passage 31 is formed in the injector body 41. One end of the first fuel passage 31 is connected to the common rail 5 via an inlet connector 45. The other end of the first fuel passage 31 is connected to the nozzle 43. The inlet connector 45 is equipped with a fuel filter 46 inside.

[0031] The nozzle 43 comprises a nozzle body 44, a nozzle needle 61, and a nozzle nut 42. The nozzle body 44 has a hole 32 that is recessed downward from its upper end. The nozzle needle 61 is housed in the hole 32 so as to be slidable in the vertical direction. The upper end of the nozzle needle 61 abuts against the lower end of the valve piston 63. In addition, a nozzle spring chamber 41b is formed in the lower part of the injector body 41, which houses a nozzle spring 79 that presses the nozzle needle 61 downward. The nozzle spring chamber 41b forms part of the through hole 41a.

[0032] The lower end of the hole 32 is the nozzle seat portion 44c, which is the seat portion of the nozzle needle 61. A fuel injection hole 44b is formed in the nozzle seat portion 44c, which connects the hole 32 to the outside of the nozzle body 44. In addition, a fuel reservoir chamber 33 is formed in a part of the hole 32 at a position opposite the pressure receiving portion 62 of the nozzle needle 61. One end of a second fuel passage 39 formed inside the nozzle body 44 communicates with the fuel reservoir chamber 33. The other end of the second fuel passage 39 communicates with the other end of the first fuel passage 31 formed in the injector body 41. The nozzle body 44 and the nozzle needle 61 are fixed to the injector body 41 by a nozzle nut 42.

[0033] The back pressure control unit 70 comprises a valve body 49, a valve nut 40, a valve ball 67, a ball holder 68, and an electromagnetic actuator 55.

[0034] The valve body 49 is mounted in the upper part of the injector body 41. The valve body 49 has a hole 49b that is recessed upward from its lower end. The upper part of the valve piston 63 is inserted into this hole 49b so as to be able to slide vertically. As a result, the portion of the hole 49b that is above the top 63a of the valve piston 63 becomes the pressure control chamber 66. The position of the central axis of the valve body 49 is determined by the inner circumferential surface of the through hole 41a formed in the injector body 41.

[0035] The valve body 49 has an opening / closing orifice 37, a pressure introduction chamber 35, and an introduction-side orifice 36. The opening / closing orifice 37 is a passage that connects the pressure control chamber 66 and the low-pressure chamber 38 located above the valve body 49. The central axis of the opening / closing orifice 37 coincides with the central axis of the valve body 49. The pressure introduction chamber 35 is formed on the side of the valve body 49. The introduction-side orifice 36 is a passage that connects the pressure control chamber 66 and the pressure introduction chamber 35.

[0036] A third fuel passage 34 is formed in the injector body 41. One end of the third fuel passage 34 is connected to the common rail 5 via an inlet connector 45. The other end of the third fuel passage 34 communicates with the pressure introduction chamber 35 of the valve body 49.

[0037] The opening / closing orifice 37 is opened and closed by a valve ball 67 that moves up and down (reciprocates) by an electromagnetic actuator 55, which will be described later. When the opening / closing orifice 37 is opened, the fuel supplied to the pressure control chamber 66 via the third fuel passage 34, the pressure introduction chamber 35, and the introduction-side orifice 36 flows out from the opening / closing orifice 37. The fuel that flows out from the opening / closing orifice 37 flows into the low-pressure chamber 38 formed above the valve body 49. Here, the flow path cross-sectional area of ​​the opening / closing orifice 37 is larger than the flow path cross-sectional area of ​​the introduction-side orifice 36. For this reason, when the opening / closing orifice 37 is opened, the pressure in the pressure control chamber 66 becomes lower than the fuel pressure in the third fuel passage 34 and the pressure introduction chamber 35.

[0038] When the opening / closing orifice 37 is closed, the valve ball 67 sits on the seat surface 49a formed on the upper part of the valve body 49. The seat surface 49a is formed such that its inner diameter increases as it moves upward from the opening / closing orifice 37 side. The central axis of the seat surface 49a coincides with the central axis of the opening / closing orifice 37, that is, the central axis of the valve body 49. As described above, the central axis of the valve body 49 is determined by the inner circumferential surface of the through hole 41a formed in the injector body 41, so the central axis of the seat surface 49a coincides with the longitudinal axis of the injector 7 (injector body 41). The valve ball 67 is held in a ball holder 68, which will be described later.

[0039] The lower end of a cylindrical holder 50 is inserted into the upper end of the injector body 41. That is, the position of the central axis of the holder 50 is determined by the inner circumferential surface of the through hole 41a formed in the injector body 41. This holder 50 is fixed to the injector body 41 via a nut 51. An electromagnetic actuator 55 that moves the valve ball 67 up and down is housed in the space above the valve body 49 within the injector body 41 and in the space within the holder 50.

[0040] The electromagnetic actuator 55 comprises a guide member 71, an armature 75, an electromagnet 80, a valve spring 86, and an armature spring 88. The guide member 71 supports the armature 75 so that it can slide vertically. This guide member 71 comprises, for example, a cylindrical guide portion 72 and a flange portion 73 provided on the outer circumference of the guide portion 72. A through hole 72a is formed in the guide portion 72, penetrating vertically. By inserting the armature 75 into this through hole 72a, the armature 75 is slidably supported by the guide portion 72. A fuel passage 73a is formed in the flange portion 73 through which the fuel in the low-pressure chamber 38 passes. The fuel that flows from the low-pressure chamber 38 into the fuel passage 73a flows out through a flow path (not shown) to a fuel discharge connection port 52, which will be described later. The fuel discharge connection port 52 is connected to a fuel tank 2. Therefore, the fuel that flows out into the fuel discharge port 52 is returned to the fuel tank 2.

[0041] The guide member 71 is housed within the injector body 41. The flange portion 73 is positioned so that it is sandwiched between the valve body 49 and the valve nut 40. In other words, the guide member 71 and the valve body 49 are fixed to the injector body 41 by the valve nut 40. The outer circumferential surface of the flange portion 73 is guided by the inner circumferential surface of the through hole 41a, and the position of the central axis of the through hole 72a of the guide member 71 is determined by the inner circumferential surface of the through hole 41a formed in the injector body 41.

[0042] The armature 75 comprises an armature bolt 78 and an armature plate 76. The armature bolt 78 is inserted into a through hole 72a of the guide member 71 and is slidably supported by the guide member 71. In other words, the position of the central axis of the armature 75, and more specifically the position of the central axis of the armature bolt 78, is determined by the through hole 72a of the guide member 71.

[0043] Below the armature bolt 78, there is a valve ball 67 that opens and closes the opening / closing orifice 37, and above the valve ball 67, there is a ball holder 68 that holds the valve ball 67. That is, the ball holder 68 is positioned between the armature bolt 78 and the valve ball 67. The ball holder 68 is substantially cylindrical in shape and has a central axis in the same direction as the longitudinal axis of the armature bolt 78, i.e., the longitudinal axis of the injector 7. A valve ball holding recess 68k is formed on the valve ball 67 side end face 68c (lower end face) of the ball holder 68 for holding the valve ball 67. The ball holder 68 also includes a rotational force generating part 90, which will be described later. When the opening / closing orifice 37 is closed by the valve ball 67, the valve ball 67 sits at the radial center of the seat surface 49a, and at this time, the central axis Z of the ball holder 68 coincides with the central axis of the armature bolt 78.

[0044] An armature plate 76 is attached to the armature bolt 78 at a portion that protrudes from the upper surface of the guide member 71 to the outside of the guide member 71. More specifically, a through hole 76a is formed in the armature plate 76 that penetrates in the vertical direction. The armature bolt 78 is slidably inserted into this through hole 76a. Here, the armature bolt 78 moves (up and down) together with the armature plate 76. For this reason, the armature plate 76 is sandwiched between a C-ring 89 attached to the armature bolt 78 and an armature spring 88 that presses the armature plate 76 against the C-ring 89. As a result, the armature bolt 78 can move (up and down) together with the armature plate 76.

[0045] The electromagnet 80 has a configuration in which a solenoid coil 82 is provided on the magnetic pole 81. This electromagnet 80 is located on the opposite side of the guide member 71, with respect to the armature plate 76. In other words, the electromagnet 80 is located above the armature plate 76. Therefore, when the solenoid coil 82 of the electromagnet 80 is energized, the magnetic force attracts the armature 75, that is, it moves the armature 75 upward.

[0046] The armature bolt 78 has a flange portion 77, which is located below the guide portion 72. The dimensions of each part are set such that a predetermined gap is formed between the flange portion 77 and the guide portion 72 when the solenoid coil 82 is not energized. When the solenoid coil 82 is energized, the flange portion 77 comes into contact with the lower end surface of the guide portion 72, thereby ending the upward movement of the armature 75. The power supplied to the solenoid coil 82 is supplied from a power supply source (not shown) connected to the energization connection port 53.

[0047] The electromagnet 80 is housed within the holder 50. A fixing member 85 is also housed within the holder 50, above the electromagnet 80. By crimping the upper end of the holder 50, the electromagnet 80 is clamped between the stepped portion formed on the inner circumferential surface of the holder 50 and the fixing member 85, thereby fixing the electromagnet 80 to the holder 50. The fixing member 85 also has the aforementioned fuel discharge connection port 52 formed therein.

[0048] The valve spring 86 presses the armature 75 toward the opening / closing orifice 37 of the valve body 49. The valve spring 86 is positioned within a through hole 83 that penetrates the electromagnet 80 vertically. The vicinity of the upper end of the valve spring 86 is housed in a valve spring recess 85a formed in the center of the lower surface of the fixing member 85. The upper end of the valve spring 86 abuts against the bottom of the valve spring recess 85a. The lower end of the valve spring 86 abuts against the upper end of the armature bolt 78. As a result, the valve spring 86 pushes the armature 75 away from the electromagnet 80 with a force corresponding to its compressed length from its natural length. In other words, the position of the central axis of the valve spring 86 is determined by the valve spring recess 85a of the fixing member 85. Furthermore, since the fixing member 85 is housed within the holder 50 as described above, the position of the central axis of the valve spring recess 85a of the fixing member 85 is determined by the holder 50.

[0049] In the injector 7 configured in this way, high-pressure fuel from the common rail 5 acts on the pressure-receiving portion 62 of the nozzle needle 61 in the fuel reservoir chamber 33 via the inlet connector 45, the first fuel passage 31, and the second fuel passage 39. In addition, the high-pressure fuel from the inlet connector 45 also acts on the top portion 63a of the valve piston 63 in the pressure control chamber 66 via the third fuel passage 34 and the pressure introduction chamber 35.

[0050] When the solenoid coil 82 of the electromagnet 80 is not energized, the armature 75 and the valve ball 67 and ball holder 68 provided at the lower end of the armature 75 are pushed down by the valve spring 86. As a result, the valve ball 67 sits on the seat surface 49a formed in the valve body 49, closing the opening / closing orifice 37. When the solenoid coil 82 of the electromagnet 80 is energized, the armature 75 is pulled upward. At this time, the valve ball 67 provided at the lower end of the armature 75 separates from the seat surface 49a due to the fuel pressure received from the pressure control chamber 66, and the valve ball 67 and ball holder 68 move upward together with the armature 75. As a result, the opening / closing orifice 37 opens.

[0051] Therefore, when the solenoid coil 82 of the electromagnet 80 is not energized, the valve ball 67 isolates the pressure control chamber 66 from the low-pressure chamber 38. As a result, the nozzle needle 61 is pressed against the nozzle seat portion 44c of the nozzle body 44 by the back pressure of the pressure control chamber 66 received via the valve piston 63 and the pressing force of the nozzle spring 79. This closes the fuel injection hole 44b.

[0052] On the other hand, when the solenoid coil 82 of the electromagnet 80 is energized, the fuel pressure in the pressure control chamber 66 is released to the low-pressure chamber 38 via the opening / closing orifice 37. That is, the high pressure acting on the top 63a of the valve piston 63 in the pressure control chamber 66 is released. As a result, the fuel pressure acting on the pressure-receiving portion 62 of the nozzle needle 61 exceeds the combined force of the fuel pressure in the pressure control chamber 66 and the pressing force of the nozzle spring 79, causing the nozzle needle 61 to rise. This opens the fuel injection hole 44b, and fuel is injected from the fuel injection hole 44b.

[0053] The ball holder 68 provided in the injector 7 according to this embodiment will be described with reference to Figure 5. Figure 5 is a diagram showing the ball holder 68 according to this embodiment, where Figure 5(a) is a front view and Figure 5(b) is a bottom view of the ball holder 68 of Figure 5(a) as seen from below.

[0054] The ball holder 68 according to this embodiment includes a rotational force generating unit 90 for rotating the ball holder 68 about its central axis Z when the valve ball 67 is separated from the seat surface 49a due to energization of the electromagnet 80. Here, the direction of the central axis Z when the ball holder 68 rotates is the longitudinal direction of the injector 7.

[0055] In this embodiment, multiple rotational force generating units 90 are formed, and when viewed from the valve ball 67 side end face 68c (lower end face) of the ball holder 68, they are formed to have the same shape at predetermined phase angles with respect to the central axis Z. In Figure 5, four rotational force generating units 90 are formed at 90-degree intervals, but the number of rotational force generating units 90 is not limited to four. For example, there could be three rotational force generating units 90 at 120-degree intervals, or five at 72-degree intervals, etc.

[0056] The rotational force generating portion 90 is formed as a recess on the outer peripheral surface 68d of the ball holder 68. Specifically, the rotational force generating portion 90 is a recess formed on the valve ball 67 side end face 68c of the ball holder 68, extending a predetermined length from the first region 90c towards the armature 75 side, when the region enclosed by the outer peripheral circle 68e forming the outer circumference of the ball holder 68, a first line segment 90a extending inward from the outer peripheral circle 68e for a predetermined length, and a second line segment 90b forming a predetermined angle with the first line segment 90a and connecting the endpoint of the first line segment 90a opposite to the outer peripheral circle 68e side to the outer peripheral circle 68e is defined as the first region 90c (see Figure 5(b)).

[0057] The predetermined length from the valve ball 67 side end face 68c of the ball holder 68 to the armature 75 side in the recessed region is as follows. If the length of the recessed region toward the armature 75 side at the first line segment 90a of the first region 90c is S (see Figure 5(a)), then at the valve ball 67 side end face 68c of the ball holder 68, as you move away from the first line segment 90a, in other words, as you move toward the intersection of the second line segment 90b and the outer circle 68e, the length of the recessed region toward the armature 75 side gradually becomes longer than S. The above recessed region length is not particularly limited, but as shown in Figure 5(a), the upper end 90e of the recessed region is located below the upper end face 68a of the ball holder 68.

[0058] The rotational force generating section 90 is formed to maintain a distance from the valve ball holding recess 68k in which the ball holder 68 holds the valve ball 67. In other words, the rotational force generating section 90 is formed in the ball holder 68 so as not to interfere with the valve ball holding recess 68k.

[0059] In this embodiment, when the electromagnet 80 is energized and the valve ball 67 is separated from the seat surface 49a, the fuel flowing out of the pressure control chamber 66 collides with the upper end portion 90e of the rotational force generating section 90. As shown in Figure 5(a), the upper end portion 90e of the rotational force generating section 90 is formed to move closer to the armature bolt 78 as it moves towards the left side of the paper. Therefore, the fuel flowing out of the pressure control chamber 66 flows along the upper end portion 90e of the rotational force generating section 90 toward the upper left of the paper. (See reference numeral 91 in Figure 5(a)) As a result, the ball holder 68 obtains a rotational force to the right in Figure 5(a), or in other words, a clockwise rotation in Figure 5(b).

[0060] Therefore, when the electromagnet 80 is energized and the valve ball 67 is lifted from the seat surface 49a, the ball holder 68 rotates about its central axis Z. As a result, after the energization of the electromagnet 80 is terminated, the valve ball 67 seats on the seat surface 49a while the ball holder 68 is moving relative to the armature bolt 78. In other words, when the valve ball 67 seats on the seat surface 49a, the frictional force at the contact surface between the armature bolt 78 and the ball holder 68 becomes smaller than in the conventional design.

[0061] Therefore, even if the valve ball 67 and the ball holder 68 are displaced radially when the valve ball 67 leaves the seat surface 49a, the valve ball 67 can easily return to the radial center of the seat surface 49a when it sits back on the seat surface 49a.

[0062] Furthermore, since the rotational force generating section 90 is formed in multiple locations such that they have the same shape at predetermined phase angles with respect to the central axis Z when viewed in the direction of the central axis Z, the ball holder 68 obtains a stable rotational force that is not biased with respect to the central axis Z.

[0063] In Figure 5(b), the intersection point of the second line segment 90b and the outer circle 68e is located in a counterclockwise direction relative to the first line segment 90a. However, the rotational force generating section 90 may be formed such that the intersection point of the second line segment 90b and the outer circle 68e is located in a clockwise direction relative to the first line segment 90a. In this case, when the electromagnet 80 is energized and the valve ball 67 is separated from the seat surface 49a, the ball holder 68 obtains a counterclockwise rotational force in Figure 5(b).

[0064] Furthermore, the first line segment 90a forming the first region 90c described above may be defined on a line extending from the outer circumference circle 68e, which forms the outer circumference of the ball holder 68, to the central axis (Z) of the ball holder 68, at the valve ball 67 side end face 68c of the ball holder 68.

[0065] Furthermore, the second line segment 90b that forms the first region 90c described above may be defined as being orthogonal to the first line segment 90a.

[0066] Furthermore, the shape of the rotational force generating section 90 is not limited to the shape described above. It is sufficient that the ball holder 68 rotates around its central axis Z due to the fuel flowing out of the pressure control chamber 66 when the valve ball 67 separates from the seat surface 49a. In other words, the present invention can be implemented if the ball holder 68 has multiple surfaces on its outer circumferential surface 68d or valve ball 67 side end surface 68c that are angled downward with respect to the central axis Z, as shown in Figure 5, with respect to the upper end portion 90e of the rotational force generating section 90, and these multiple surfaces are formed to have the same shape at predetermined phase angles with respect to the central axis Z when viewed in the direction of the central axis Z.

[0067] Furthermore, the present invention makes it possible to form a rotational force generating section 90 on a conventionally used ball holder 68 by additional cutting. In this case, there is no need to make major changes to the process. When the rotational force generating section 90 is formed by cutting, cutting is performed from the portion of the first region 90c toward the armature bolt 78. At this time, the cutting length toward the armature bolt 78 in the first line segment 90a of the first region 90c is S. Also, as one moves away from the first region 90c, in other words, toward the intersection of the second line segment 90b and the outer circle 68e, the cutting length toward the armature 75 gradually becomes longer than S.

[0068] Alternatively, the shape of the rotational force generating section 90 described above may be formed by press working. In this case, it can be manufactured at a lower cost than forming the rotational force generating section 90 by cutting.

[0069] (Second Embodiment) Next, a second embodiment of the present invention will be described. The second embodiment will be described in terms of its differences from the first embodiment, while the parts that are the same as those in the first embodiment will not be described.

[0070] Figure 6 shows the armature bolt 78 of the armature 75 according to the second embodiment. In the second embodiment, the armature bolt 78 has an armature-side recess 78b on the contact surface (hereinafter also referred to as the lower end surface) 78a with respect to the ball holder 68. The second embodiment is the same as the first embodiment except that the armature bolt 78 has an armature-side recess 78b.

[0071] The surface of the armature-side recess 78b has a substantially spherical shape, and the amount of recess increases towards the radial center. The amount of recess of the armature-side recess 78b is not particularly limited and can be appropriately determined depending on the size of surrounding parts such as the valve ball 67 and ball holder 68. Furthermore, the inner diameter (diameter) of the armature-side recess 78b at the lower end face 78a of the armature bolt 78 is formed to be larger than the diameter of the outer circumferential surface 68d of the ball holder 68 positioned below the armature bolt 78.

[0072] With the above configuration, when the ball holder 68 rotates relative to the armature bolt 78, the ball holder 68 tends to move toward the radial center of the armature bolt 78. In other words, the armature-side recess 78b provides an auto-aligning function for the ball holder 68.

[0073] As a result, even if the valve ball 67 and the ball holder 68 are displaced radially when the valve ball 67 leaves the seat surface 49a, the valve ball 67 can more easily return to the radial center of the seat surface 49a when it sits back on the seat surface 49a.

[0074] (Third embodiment) Next, a third embodiment of the present invention will be described. The third embodiment will be described in terms of its differences from the first embodiment, while the parts identical to the first embodiment will not be described.

[0075] Figure 7 shows a ball holder 68 according to the third embodiment, where Figure 7(a) is a front view and Figure 7(b) is a bottom view of the ball holder 68 of Figure 7(a) viewed from below. In the third embodiment, the shape of the rotational force generating part 90 formed on the ball holder 68 is different from that of the first embodiment.

[0076] In this embodiment, as in the first embodiment, the rotational force generating unit 90 also rotates the ball holder 68 around its central axis Z when the valve ball 67 is lifted from the seat surface 49a by energizing the electromagnet 80. In this embodiment as well, the direction of the central axis Z when the ball holder 68 rotates is the longitudinal direction of the injector 7.

[0077] Furthermore, multiple rotational force generating units 90 are formed in this embodiment, and are formed so that, when viewed from the valve ball 67 side end face (lower end face) of the ball holder 68, they have the same shape at predetermined phase angles with respect to the central axis Z. In Figure 7, four rotational force generating units 90 are formed at 90-degree intervals, but the number of rotational force generating units 90 is not limited to four. For example, there could be three rotational force generating units 90 at 120-degree intervals, or five at 72-degree intervals, etc.

[0078] In this embodiment, the rotational force generating section 90 is formed by a first processed section 90g and a second processed section 90h. The first processed section 90g is formed as a hole drilled over a predetermined length from the valve ball 67 side end face 68c of the ball holder 68 toward the armature 75 side. The second processed section 90h is formed as a hole connecting the outer circumferential surface 68d of the ball holder 68 and the armature 75 side end of the first processed section 90g. The length of the first processed section 90g is not particularly limited, but it does not reach the upper end face 68a of the ball holder 68.

[0079] Furthermore, the second machining section 90h is formed such that the extension of its central axis does not intersect with the central axis Z of the ball holder 68. In other words, the central axis of the second machining section 90h and the central axis Z of the ball holder 68 are in a twisted position.

[0080] Furthermore, in this embodiment as well, the rotational force generating unit 90 is formed to maintain a distance from the valve ball holding recess 68k in which the ball holder 68 holds the valve ball 67. In other words, the rotational force generating unit 90 is formed in the ball holder 68 so as not to interfere with the valve ball holding recess 68k.

[0081] In this embodiment, when the electromagnet 80 is energized and the valve ball 67 is separated from the seat surface 49a, the fuel that has flowed out from the pressure control chamber 66 flows out from the second processing section 90h via the first processing section 90g. At that time, the ball holder 68 obtains a clockwise rotational force as shown in Figure 7(b).

[0082] Therefore, when the electromagnet 80 is energized and the valve ball 67 is lifted from the seat surface 49a, the ball holder 68 rotates about its central axis Z. As a result, after the energization of the electromagnet 80 is terminated, the valve ball 67 seats on the seat surface 49a while the ball holder 68 is moving relative to the armature bolt 78. In other words, when the valve ball 67 seats on the seat surface 49a, the frictional force at the contact surface between the armature bolt 78 and the ball holder 68 becomes smaller than in the conventional design.

[0083] Therefore, even if the valve ball 67 and the ball holder 68 are displaced radially when the valve ball 67 leaves the seat surface 49a, the valve ball 67 can easily return to the radial center of the seat surface 49a when it sits back on the seat surface 49a.

[0084] Furthermore, since the rotational force generating section 90 is formed in multiple locations such that they have the same shape at predetermined phase angles with respect to the central axis Z when viewed in the direction of the central axis Z, the ball holder 68 obtains a stable rotational force that is not biased with respect to the central axis Z.

[0085] In Figure 7(b), the second processing section 90h is formed in a counterclockwise region relative to the first processing section 90g, but the second processing section 90h may also be formed in a clockwise region relative to the first processing section 90g. In this case, when the electromagnet 80 is energized and the valve ball 67 is separated from the seat surface 49a, the ball holder 68 obtains a counterclockwise rotational force in Figure 7(b).

[0086] Furthermore, the first processed portion 90g described above may be formed perpendicular to the valve ball 67 side end face 68c of the ball holder 68.

[0087] Furthermore, the second processing section 90h may be formed perpendicular to the first processing section 90g.

[0088] Furthermore, in this embodiment, the rotational force generating section 90 can be formed by adding a relatively simple process, such as drilling a hole, to the conventionally used ball holder 68. Therefore, there is no need to make significant changes to the process compared to the conventional method.

[0089] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described. Figure 8 shows an armature bolt 78 of the armature 75 according to the fourth embodiment. In the fourth embodiment, the armature bolt 78 has an armature-side recess 78b on its lower end face 78a, that is, on the surface that contacts the ball holder 68. The fourth embodiment is the same as the third embodiment except that the armature bolt 78 has an armature-side recess 78b.

[0090] The features and effects of the fourth embodiment are the same as those of the second embodiment described above, so a further explanation will be omitted.

[0091] As described above, according to the present invention, when the opening / closing orifice 37 is closed, the valve ball 67 can be reliably seated at the radial center of the seat surface 49a.

[0092] Furthermore, in some cases, a so-called "dry-firing" control is performed on the injector 7. After the electromagnet 80 is energized, the valve ball 67 moves away from the seat surface 49a, but the energization to the electromagnet 80 is terminated before the nozzle needle 61 rises, causing the valve ball 67 to seat on the seat surface 49a. This dry-firing control allows the rail pressure to be reduced in a short time without injecting fuel. Even when dry-firing control is performed, the present invention functions effectively because fuel flows out of the pressure control chamber 66 when the electromagnet 80 is energized. [Explanation of symbols]

[0093] 7: Injector, 44b: Fuel injection port, 49: Valve body, 61: Nozzle needle, 66: Pressure control chamber, 67: Valve ball, 68: Ball holder, 68c: End face, 68d: Outer circumference, 68e: Outer circumference circle, 68k: Recess for holding valve ball, 75: Armature, 78a: Contact surface (lower end face), 78b: Armature-side recess, 80: Electromagnet, 86: Valve spring, 90: Rotational force generating section, 90a: First line segment, 90b: Second line segment, 90c: First region, 90g: First machining section, 90h: Second machining section, Z: Central axis

Claims

1. An electromagnet (80) that attracts the armature (75) when energized, A valve spring (86) presses the armature (75) in a direction away from the electromagnet (80), A valve body (49) having a pressure control chamber (66) that presses the nozzle needle (61) in a direction that closes the fuel injection hole (44b), A valve ball (67) capable of closing the pressure control chamber (66) by the pressing force of the valve spring (86), A ball holder (68) is positioned between the armature (75) and the valve ball (67), An injector (7) equipped with, The ball holder (68) is provided with a rotational force generating unit (90) for rotating the ball holder (68) around its central axis (Z) by the flow of fuel that flows out from the pressure control chamber (66) when the electromagnet (80) is energized, in the injector (7).

2. The rotational force generating part (90) is a recess formed in the ball holder (68), The recess is a region extending a predetermined length from the first region (90c) towards the armature (75) side, when the region enclosed by the outer circle (68e) forming the outer circumference of the ball holder (68), a first line segment (90a) extending inward from the outer circle (68e), and a second line segment (90b) that forms a predetermined angle with the first line segment (90a) and connects the endpoint of the first line segment (90a) opposite to the outer circle (68e) side to the outer circle (68e), the recess is a region extending a predetermined length from the first region (90c) towards the armature (75) side, on the valve ball (67) side end face (68c) of the ball holder (68). The predetermined length toward the armature (75) side is determined based on the length toward the first line segment (90a) side, and increases as it moves away from the first line segment (90a) side. The rotational force generating section (90) is formed such that the ball holder (68) maintains a distance from the valve ball holding recess (68k) that holds the valve ball (67), and is formed to have the same shape at predetermined phase angles with respect to the central axis (Z). The injector (7) according to claim 1.

3. The first line segment (90a) lies on a line extending from the outer circle (68e) to the central axis (Z) of the ball holder (68), The second line segment (90b) is perpendicular to the first line segment (90a), The injector (7) according to claim 2.

4. The rotational force generating section (90) is formed by a first processing section (90g) and a second processing section (90h), The first processed portion (90g) is formed as a hole drilled from the valve ball (67) side end face (68c) of the ball holder (68) toward the armature (75) side, The second processed portion (90h) is formed as a hole that connects the outer circumferential surface (68d) of the ball holder (68) and the armature (75) side end of the first processed portion (90g), The rotational force generating section (90) is formed such that the ball holder (68) maintains a distance from the valve ball holding recess (68k) that holds the valve ball (67), and is formed to have the same shape at predetermined phase angles with respect to the central axis (Z). The injector (7) according to claim 1.

5. The longitudinal central axis of the second processing section (90h) is formed to maintain a predetermined distance from the central axis (Z) of the ball holder (68). The injector (7) according to claim 4.

6. The first processed portion (90g) is formed perpendicular to the valve ball (67) side end face (68c) of the ball holder (68), The injector (7) according to claim 5.

7. The second processing section (90h) is formed perpendicular to the first processing section (90g), The injector (7) according to claim 6.

8. The injector (7) according to any one of claims 1 to 7, wherein the armature (75) has an armature-side recess (78b) on the contact surface (78a) with the ball holder (68) such that the amount of recess increases towards the radial center.

9. The injector (7) according to claim 8, wherein the inner diameter of the armature-side recess (78b) at the contact surface (78a) with the ball holder (68) is larger than the outer diameter of the ball holder (68).

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