JP2007092714A - Amount adjustment valve and fuel injection pump using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an amount adjustment valve and a fuel injection pump using it which can improve the controllability of a low-flow zone by a simple structure. <P>SOLUTION: The amount adjustment valve 40 provided at a midpoint in a passage adjusts opening areas of the openings 62, 63 and a flow rate of fluid which circulates through the passage. Then the amount adjustment valve 40 is provided with a valve body 70, an energizing means 90, and an electromagnetic driving means 80. The valve body 70 adjusts the opening areas of the openings 62, 63, and an energizing means 90 energizes the valve body 70 in a predetermined direction. Then the electromagnetic driving means 80 draws in the valve body 70 against the energizing force of the energizing means 90 when a coil 85 is energized. The openings 62, 63 are formed of at least two openings which are opened in the low-flow zone, and one of the openings 62 is opened ahead of the other opening 63 in the low-flow zone. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a metering valve that is installed in the middle of a flow path, adjusts the opening area of an opening, and adjusts the flow rate of fluid flowing through the flow path, and a fuel injection pump using the same.

  For example, a common rail fuel injection system is known as a fuel injection system that supplies fuel to a diesel engine and injects the supplied fuel into a combustion chamber. Common rail type fuel injection systems include, for example, a low pressure pump that pressurizes fuel to a predetermined pressure, a common rail that stores fuel pressurized by the fuel injection pump in a high pressure state, and an injector that injects fuel stored in the common rail into a combustion chamber Etc.

  In the common rail fuel injection system, it is necessary to adjust the flow rate of the fuel supplied from the low pressure pump to the fuel injection pump in order to keep the fuel pressure stored in the common rail constant according to the operation state of the diesel engine. is there.

  Conventionally, a fuel injection pump is a plunger pump that operates with a camshaft that rotates in synchronization with a crankshaft of a diesel engine, and a metering valve is installed on the inlet side of the pressurizing chamber of the plunger pump. This metering valve includes, for example, a valve body that opens and closes an opening provided in the valve using an electromagnetic attraction force, and the pressure chamber is adjusted by adjusting the opening area of the opening by the valve body. The flow rate of the fuel supplied to is adjusted (see Patent Document 1).

  The metering valve includes a valve body and a valve body that houses the valve body in an axially movable manner. The valve body and the valve body move relatively in the axial direction, and the valve body is attracted by the electromagnetic drive means. Further, the valve body is urged by the urging means in the direction opposite to the direction attracted by the electromagnetic drive means.

The relative positional relationship between the valve body and the valve body changes due to the balance of force between the electromagnetic driving means and the biasing means. Therefore, the area (opening area) where the opening formed in the valve body and the opening formed in the valve body communicate with each other changes, and the flow rate of the fuel flowing there changes. The change in the opening area is proportional to the magnitude of the current supplied to the electromagnetic driving means.
JP 2003-120845 A

  Since the fuel injection pump operates in synchronization with the rotation of the crankshaft, the moving speed of the plunger changes in accordance with the rotational range of the engine. In the low rotation range, the movement speed of the plunger is lower than in the high rotation range, and the suction time of the plunger pump is longer than in the high rotation range. Therefore, a large amount of fuel is supplied to the pressurizing chamber of the plunger pump even in the low flow rate region where the opening area of the opening is reduced by the metering valve. Further, in this flow rate region, the amount of fuel sucked into the pressurizing chamber per unit opening area of the opening, in other words, per unit current of the current supplied to the electromagnetic drive means is larger than that in the high flow rate region. Therefore, it has been very difficult to control the common rail pressure in the low rotation range to a predetermined value.

  As a countermeasure, a method has been devised in which the width of the opening that opens in the low flow area of the metering valve is reduced. According to this, since the change amount of the opening area per unit current in the low flow rate region becomes smaller, the controllability of the fuel injection pump (plunger pump) in the low rotation region is improved, and the controllability of the common rail pressure is also improved. To do.

  There is a desire to further improve the controllability of the metering valve in the low flow range and further improve the controllability of the common rail pressure in the low rotation range. A means for further reducing the width of the opening that opens in the low flow rate region as described above can be considered, but problems such as difficulty in processing the opening and an increase in processing costs arise.

  The present invention has been made in view of the above points, and an object thereof is to provide a metering valve capable of improving the flow rate controllability in a low flow rate region with a simple structure and a fuel injection pump using the same. There is.

  In order to achieve the above object, the metering valve according to claim 1 is installed in the middle of the flow path, adjusts the opening area of the opening, and adjusts the flow rate of the fluid flowing through the flow path. The valve body for adjusting the opening area of the opening, the biasing means for biasing the valve body in a predetermined direction, and when the coil is energized, it resists the biasing force of the biasing means. And an electromagnetic drive means for suction, and the opening is composed of at least two openings that open in a low flow area, and one opening is opened before the other opening in the low flow area. It is characterized by that.

  According to the metering valve according to claim 1, since at least two openings are formed so that one opening is opened before the other opening, the opening that opens in a low flow rate region. The opening time of is shifted. Then, from the opening of one opening until the opening of the other opening, the opening per unit current value of the current applied to the coil of the electromagnetic driving means or the unit movement amount of the valve body The amount of change in the opening area is smaller than that of a metering valve in which both openings are opened at the same time. As a result, the flow rate controllability in the low flow rate region can be improved with a simple structure.

  As described in claim 2, the shape of the opening of the metering valve described in claim 1 is more specifically the length of one opening than the length of the other opening. Is also getting longer. According to this, one opening part can be easily opened ahead of the other opening part.

  As described in claim 3, the opening of the metering valve described in claim 1 or claim 2 includes a first region used in a low flow region and a second region used in a high flow region. And the width of the opening in the first region is smaller than the width of the opening in the second region. According to this, in the low flow rate range, the change amount of the flow rate per unit current and per unit movement amount of the valve body is small, and in the high flow rate range, the change amount of the flow rate is increased to ensure a large flow rate. it can.

  As described in claim 4, the width of the opening in the first region of the metering valve according to claim 3 is substantially the same from the tip of the first region to the boundary portion with the second region. . According to this, the change amount of the opening area per unit current in the first region and per unit movement amount of the valve body becomes substantially constant, and controllability is further improved.

  As described in claim 5, the metering valve according to any one of claims 1 to 4 is configured such that when the energization of the coil is stopped, the valve body is attached to the urging means. It is characterized by being moved to a position where one opening and the other opening are fully closed by the force. In addition, as described in claim 6, the metering valve according to any one of claims 1 to 4 is configured such that when the energization of the coil is stopped, the valve body is a biasing means. The urging force is used to move the one opening and the other opening to a position where they are fully opened.

  As described in claims 5 and 6, even a so-called normally closed type or normally open type metering valve is described in any one of claims 1 to 4. The effects of the invention can be obtained.

  As described in claim 7, the metering valve according to any one of claims 1 to 6 has a valve body in a cylindrical valve body having a passage hole at one end. The valve body is accommodated so as to be relatively movable in the axial direction, and one opening and the other opening are formed in the valve body, and the valve body is connected to one opening or the other opening and the passage hole. One communication path is formed.

  Moreover, as described in claim 8, the metering valve described in any one of claims 1 to 6 is a tubular valve body having a valve body having a passage hole at one end. The valve body is accommodated so as to be relatively movable in the axial direction, and the valve body has one opening and the other opening, and a second communication path in which the one opening and the other opening and the passage hole communicate with each other. The valve body is formed with a third communication passage that communicates one opening and the other opening with the outside of the valve body.

  As described in claims 7 and 8, one opening and the other opening may be formed in either the valve body or the valve body.

  As described in claim 9, the valve body and valve body of the metering valve according to claim 8 are provided with guide means for guiding the valve body in the axial direction of the valve body. It is said. Thereby, it can prevent that a valve body and a valve body rotate in the circumferential direction, and can make one opening part and the other opening part communicate with a 3rd communicating path reliably.

  According to a tenth aspect of the present invention, the fuel injection pump includes a housing in which a pressurizing chamber in which fuel is pressurized is formed, and is installed in the housing so as to be able to reciprocate and is sucked into the pressurizing chamber. A metering valve according to any one of claims 1 to 9, wherein a movable member that pressurizes the fuel, a driving unit that drives the movable member, and a flow rate of fuel sent to the pressurizing chamber are adjusted. It is characterized by having.

  Accordingly, by applying the metering valve according to any one of claims 1 to 9 to the fuel injection pump, it is possible to improve the controllability of the pump pumping amount in the low rotation range.

  Hereinafter, a plurality of embodiments showing embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a common rail fuel injection system for a diesel engine (hereinafter referred to as an engine) to which a metering valve according to a first embodiment of the present invention is applied.

  The fuel injection system 1 mainly includes an injector 2, a common rail 3, a fuel injection pump 4, a fuel filter 5, and a fuel tank 6. The engine (not shown) is provided with a plurality of injectors 2 corresponding to the combustion chambers of the respective cylinders. The injector 2 is connected to a common rail 3 common to each cylinder via a fuel pipe 14. A fuel injection pump 4 is connected to the common rail 3 via a fuel pipe 15, and high predetermined pressure fuel corresponding to the fuel injection pressure is continuously accumulated as the fuel injection pump 4 is driven.

  The fuel injection pump 4 mainly includes a feed pump 23, a plunger pump 24, and a metering valve 40. The detailed configuration of the fuel injection pump 4 will be described later. The feed pump 23 sucks fuel from the fuel tank 6 through the fuel pipe 16 and the fuel filter 5 and sends the fuel to the plunger pump 24. The plunger pump 24 pressurizes the fuel sent from the feed pump 23 and feeds the fuel toward the common rail 3. A fuel discharge pipe 17 is connected to the fuel injection pump 4, and the fuel used to lubricate the components of the fuel injection pump 4 is returned to the fuel tank 6 through the pipe 17.

  The common rail 3 is provided with a pressure sensor 8 for detecting the internal fuel pressure (common rail pressure). The electronic control unit (hereinafter referred to as ECU) 7 determines the pumping amount of the fuel injection pump 4 so that the actual common rail pressure detected by the pressure sensor 8 becomes an optimum value set based on the load and the rotational speed. Then, a control signal (current) corresponding thereto is output to the metering valve 40.

  Engine operation information such as a rotation angle and a load is input to the ECU 7 from a rotation angle sensor 9 and a load sensor (for example, a throttle opening sensor) 10. In addition, the ECU 7 is connected with a coolant temperature sensor 11 that detects the engine coolant temperature, an intake air temperature sensor 12, and an intake pressure sensor 13 that detects the intake pressure. Detection signals from the sensors are input to the ECU 7 as needed. The ECU 7 determines the optimum fuel injection timing and injection amount (injection period) based on the engine operating state based on the detection signals of these sensors, and outputs a control signal corresponding to the fuel injection timing to the injector 2. Thereby, fuel injection from the injector 2 to each combustion chamber of the engine is controlled.

  Next, the configuration of the fuel injection pump 4 will be described with reference to FIG. As shown in FIG. 1, cylinder heads 21 and 22 are respectively fixed to the upper and lower surfaces of the pump housing 20 of the fuel injection pump 4. The cylinder heads 21 and 22 support the plungers 25 and 26 of the plunger pump 24 so as to be reciprocally movable. Fuel pressurization chambers 29 and 30 formed by end surfaces of the plungers 25 and 26 and inner wall surfaces of the cylinder heads 21 and 22 are formed above the plunger 25 and below the plunger 26. The cylinder heads 21 and 22 are provided with intake valves 41 and 42 for controlling the flow of low-pressure fuel supplied from the feed pump 23 to the pressurization chambers 29 and 30. Fuel supply paths 50 and 51 through which the low-pressure fuel flows are connected to the intake valves 41 and 42. The intake valves 41 and 42 are so-called open valves, and are opened when the plungers 25 and 26 suck the fuel, and are closed when the plungers 25 and 26 pressurize the fuel.

  As shown in FIG. 1, a camshaft 31 that rotates in synchronization with the rotation of the engine is rotatably supported in the pump housing 20. On the outer periphery of the intermediate portion of the camshaft 31, a cam 32 is formed integrally with the camshaft 31 so as to be eccentric. On the outer periphery of the cam 32, a shoe 33 having a square outer shape is slidably held.

  Plungers 25 and 26 are disposed on the upper and lower end surfaces of the shoe 33, and plate members integrated with the plungers 25 and 26 are pressed against the shoe 33 by the urging force of the springs 27 and 28. The cam shaft 31, the cam 32, the shoe 33, the springs 27 and 28, and the plate portions of the plungers 25 and 26 are accommodated in a pump cam chamber 52 formed by the inner wall surface of the pump housing 20 and the wall surfaces of the cylinder heads 21 and 22. Yes.

  When the cam 32 integrated with the camshaft 31 rotates, the shoe 33 revolves along a predetermined circular path, and the plate member reciprocally slides on the upper and lower end surfaces of the shoe 33. Accordingly, the plungers 25 and 26 move up and down in the cylinder heads 21 and 22 to suck low pressure fuel into the pressurizing chambers 29 and 30 and pressurize the fuel in the pressurizing chambers 29 and 30. The fuel pressurized by the plunger 25 is pumped to the common rail 3 through the discharge valve 43 and the fuel outlet 46 provided in the cylinder head 21. Although not shown in FIG. 1, the cylinder head 22 is also provided with the same components as the discharge valve 43 and the fuel outlet 46, and the fuel pressurized by the plunger 26 is discharged from the discharge valve and the fuel. It is pumped to the common rail 3 through the outlet.

  The pump housing 20 sucks the fuel in the fuel tank 6 and supplies the fuel to the pressurizing chambers 29 and 30, and adjusts the flow rate of the fuel sent to the pressurizing chambers 29 and 30. A quantity valve 40 is provided. The feed pump 23 is a gear pump composed of an inner gear and an outer gear, and the fuel in the fuel tank 6 is supplied to the fuel pipe 16, the fuel filter 5 and the pump housing 20 by rotating the inner gear with the camshaft 31. The air is sucked through the inlet 45 and sent to the fuel flow paths 48 and 49.

  The fuel flow path 48 is connected to the metering valve 40, and the fuel flow path 49 is connected to the pump cam chamber 52. The fuel that has flowed into the pump cam chamber 52 lubricates the camshaft 31, the cam 32, the shoe 33, the sliding portions of the plungers 25 and 26, and the like. Thereafter, the fuel in the pump cam chamber 52 returns to the fuel tank 6 via the overflow outlet 47 and the fuel discharge pipe 17.

  The feed pump 23 is provided with a regulating valve 44 for preventing the fuel pressure sent to the fuel flow paths 48 and 49 from exceeding a predetermined pressure. As a result, low-pressure fuel having a substantially constant pressure can be circulated through the fuel flow paths 48 and 49.

  The metering valve 40 is provided between the fuel flow path 48 and the fuel supply paths 50 and 51, and adjusts the flow rate of the fuel sent to the fuel supply paths 50 and 51. The fuel whose flow rate is adjusted flows into the pressurizing chambers 29 and 30 through the fuel supply paths 50 and 51 and the intake valves 41 and 42.

  Next, the configuration of the metering valve 40 will be described with reference to FIG. FIG. 2 is a cross-sectional view of the metering valve 40 according to the present embodiment. As shown in FIG. 2, the metering valve 40 includes a valve body 60, a spool valve 70 as a valve body, an electromagnetic drive unit 80 as electromagnetic drive means, and a spring 90 as urging means.

  The valve body 60 is formed in a substantially cylindrical shape, and accommodates the spool valve 70 therein so as to be capable of reciprocating in the axial direction. An inlet port 61 as a passage hole connected to the fuel flow path 48 is formed at the end of the valve body 60. A first outlet port 62 and a second outlet port 63 are formed on the side wall of the valve body 60 so as to penetrate the space in which the spool valve 70 is accommodated. These outlet ports 62 and 63 correspond to the openings described in the claims. These outlet ports 62 and 63 are connected to the fuel supply paths 50 and 51. The shapes of these outlet ports 62 and 63 will be described later. The valve body 60 is fixed to the pump housing 20 so that the inlet port 61 is connected to the fuel flow path 48 and the first and second outlet ports 62 and 63 are connected to the fuel supply paths 50 and 51. An O-ring 100 is provided between the valve body 60 and the pump housing 20.

  The spool valve 70 is formed in a substantially cylindrical shape, and a valve body passage 71 communicating with the inlet port 61 is formed therein. A concave groove 72 is formed in the side wall of the spool valve 70 over the entire circumference of the spool valve 70. The spool valve 70 is formed with a plurality of through holes 73 through which the valve body passage 71 and the recessed groove 72 pass. As a result, the fuel flowing through the fuel flow path 48 reaches the concave groove 72 via the inlet port 61 of the valve body 60, the valve body passage 71, and the through hole 73. The valve body passage 71, the through hole 73, and the concave groove 72 correspond to a first communication passage according to claim 7.

  When the spool valve 70 moves to the right from the position shown in FIG. 2, the first and second outlet ports 62 and 63 formed in the valve body 60 communicate with the concave groove 72, and the concave groove 72. Reaches the fuel supply passages 50 and 51 via the first and second outlet ports 62 and 63. By adjusting the position of the spool valve 70, the opening areas of the first and second outlet ports 62 and 63 communicating with the concave groove 72 can be changed. As a result, the amount of fuel flowing through the fuel supply passages 50 and 51 can be adjusted.

  Next, a mechanism for adjusting the position of the spool valve 70 with respect to the valve body 60 will be described. Between the end of the spool valve 70 opposite to the side where the valve body passage 71 is formed and the end of the valve body 60 opposite to the side where the inlet port 61 is formed, A spring 90 that biases 70 toward the inlet port 61 of the valve body 60 is provided. On the other hand, a stopper 110 that restricts movement of the spool valve 70 biased by the spring 90 is provided in the vicinity of the inlet port 61 of the valve body 60.

  An electromagnetic drive unit 80 is provided outside the valve body 60. The electromagnetic drive unit 80 includes a housing 81, a stator 84, a coil 85, and a yoke 86. In the present embodiment, the stator 84 is formed integrally with the valve body 60. Of course, the stator 84 and the valve body 60 may be formed separately.

  A coil 85 around which a winding is wound is provided on the outside of the stator 84. Further, a yoke 86 formed in a substantially cylindrical shape is provided on the outside thereof. A flange 87 for fixing the metering valve 40 to the pump housing 20 using a bolt or the like is formed at one end of the yoke 86. A housing 81 having a connector 82 is provided at the other end of the yoke 85. The connector 82 is provided with an electrode 83 so that a current corresponding to a signal from the ECU 7 can be applied to the coil 85.

  The stator 84, the yoke 86, and the spool valve 70 are all made of a magnetic material. When a current is applied to the coil 85, a magnetic field is generated in the coil 85, and a magnetic circuit passing through the stator 84, the yoke 86, and the spool valve 70 is formed by the generated magnetic field. Therefore, a suction force is generated in the stator 84 and the spool valve 70 moves in the direction of the stator 84.

  The amount of movement of the spool valve 70 and the position of the spool valve 70 with respect to the valve body 60 are determined by the balance between the urging force of the spring 90 and the suction force. The spool valve 70 stops at a position where the urging force and the suction force are balanced, and remains in that position. The attractive force changes according to the magnitude of the current applied to the coil 85. Therefore, the magnitude of the current applied to the coil 85 and the amount of movement of the spool valve 70 are proportional.

  Next, the shape of the first and second outlet ports 62 and 63 will be described with reference to FIG. FIG. 3 is a plan view of the first and second outlet ports 62 and 63. In FIG. 3, in order to facilitate the explanation of both outlet ports 62 and 63, the valve body 60 is expanded, and both outlet ports 62 and 63 are arranged close to each other vertically. In the drawing, the upper port is the second outlet port 63, and the lower port is the first outlet port 62.

  The first outlet port 62 includes a first slit portion 64 as a first region used in the low flow region on the inlet port 61 side, and a first wide portion 66 as a second region used in the high flow region on the stator 84 side. It consists of and. As shown in FIG. 3, the first slit portion 64 is formed such that a slit having a width b <b> 1 extends in the axial direction of the valve body 60. A first wide portion 66 having a width wider than the width b1 is formed at the end of the first slit portion 64 on the stator 84 side. Similarly to the first outlet port 62, the second outlet port 63 includes a second slit portion 65 and a second wide portion 67. The width b2 of the second slit portion 65 is substantially the same as the width b1 of the first slit portion 64. The width of the second wide portion 67 is also substantially the same as the width of the first wide portion 66.

  The length of the first slit portion 64 is larger than that of the second slit portion 65. Furthermore, the first slit portion 64 is such that the end portion on the inlet port 61 side of the first slit portion 64 is closer to the inlet port 61 than the end portion on the inlet port 61 side of the second slit portion 65. Is formed.

  Next, the flow characteristics of the metering valve 40 of the present embodiment will be described in comparison with a metering valve having an outlet port shown in FIG. First, the structure and flow rate characteristics of the outlet port of the metering valve of the comparative example will be described with reference to FIGS.

  Since the metering valve of the comparative example is the same as the metering valve 40 of this embodiment except for the shape of the outlet port, the description thereof is omitted. The same function and the same function as the metering valve 40 of the present embodiment use the same name and code. As shown in FIG. 10, the metering valve of the comparative example has first and second outlet ports 620 and 630 having substantially the same shape. These outlet ports 620 and 630 are respectively composed of a first slit portion 640, a second slit portion 650, a first wide portion 660, and a second wide portion 670. The width b of the first and second slit portions 640 and 650 is substantially the same width b1 and b2 as the first and second slit portions 64 and 65 of the metering valve 40 of the present embodiment.

  The lengths of the first and second slit portions 640 and 650 of the metering valve of the comparative example are substantially the same. As shown in FIG. 10, the first and second outlet ports 620 and 630 are formed so that the end portions of the first and second slit portions 640 and 650 are aligned in the axial direction.

  Since this metering valve is a normally closed type valve, the concave groove 72 of the spool valve 70 communicates with the first and second slit portions 640 and 650 when no current is applied to the coil 85. Therefore, the flow rate is 0 as shown in FIG.

  When a current is applied to the coil 85, the spool valve 70 moves in the direction of the stator 84. Then, the concave groove 72 and the first and second slit portions 640 and 650 first communicate with each other, and the fuel flowing in from the inlet port 61 flows out from the first and second slit portions 640 and 650. The area (opening area) where the concave groove 72 communicates with the first and second slit portions 640 and 650 varies depending on the magnitude of the current applied to the coil 85. As shown in FIG. 11, the flow rate of fuel in the region where the first and second slit portions 640 and 650 communicate with the concave groove 72 (low flow rate region) changes with a relatively low change amount as the opening area increases.

  When the magnitude of the current applied to the coil 85 is further increased, the concave groove 72 communicates with the first and second wide portions 660 and 670, and the fuel flowing from the inlet port 61 flows into the first and second slit portions. 640 and 650 and the first and second wide portions 660 and 670 flow out. The flow rate of the fuel flowing out in the region (high flow rate region) where the first and second slit portions 640 and 650 and the first and second wide portions 660 and 670 communicate with the concave groove 72 is the first and second wide portions 660. , 670 as the opening area increases. Since the first and second wide portions 660 and 670 are wider than the first and second slit portions 640 and 650, the flow rate of fuel is larger than the change in flow rate in the low flow rate region as shown in FIG. It changes with a large amount of change.

  There is a demand for a metering valve to further improve the controllability of the flow rate in a low flow rate region. In the metering valve of the comparative example, in order to achieve the above demand, if the width b of the first and second slit portions 640 and 650 is further reduced, the amount of change in the flow rate per unit current in the low flow rate region is The flow rate in this region can be improved. However, problems such as difficulty in processing the first and second slit portions 640 and 650 and an increase in processing costs arise.

  Next, the flow characteristics of the metering valve 40 of this embodiment will be described with reference to FIG. In the metering valve 40 of the present embodiment, when a current is applied to the coil 85 and the spool valve 70 is moved in the direction of the stator 84 in the low flow rate region, only the first slit portion 64 is initially the concave groove 72. Communicate with. Further, when the current is increased, the second slit portion 65 communicates with the concave groove 72. As shown in FIG. 4, the change amount of the opening area per unit current Δi at the time when only the first slit portion 64 in this region communicates with the concave groove 72 is the opening area of the metering valve of the comparative example. It becomes smaller than the amount of change. Therefore, as shown in the low flow rate region of FIG. 4, the flow rate change amount Δq1 per unit current Δi of the metering valve 40 of this embodiment is smaller than the flow rate change amount Δq0 of the comparative example. Thereby, the controllability in the low flow rate region can be improved with a simple structure without increasing the processing difficulty and the processing cost.

  Note that the shape of the outlet port is not limited to the outlet port having the slit portion and the wide portion as shown in the present embodiment. Of the at least two outlet ports, the outlet port may have any shape as long as one outlet port communicates with the concave groove before the other outlet port. For example, it may be a substantially rectangular outlet port or a substantially triangular outlet port. Further, the widths b1 and b2 of the first and second slit portions 64 and 65 need not be the same.

  Moreover, since the widths b1 and b2 of the first and second slit portions 64 and 65 are substantially the same from the tip to the first and second wide portions 66 and 67, the unit current in the low flow rate region The amount of change of the opening area per unit and the unit movement amount of the valve body becomes substantially constant, and the controllability of the flow rate is further improved.

  In addition, since the first and second slit portions are smaller in width than the first and second wide portions, the amount of change in flow rate per unit current and per unit movement amount of the valve body is small in the low flow rate region, In the high flow rate region, the amount of change in flow rate can be increased to ensure a large flow rate.

  In addition, as shown in FIG. 5, when the applied current is 0, the opening area of the first and second outlet ports 62 and 63 is maximized, and when the applied current is maximized, the opening area is minimized. Of course, even a so-called normally open type metering valve can provide the same effects as those of the present embodiment.

  Of course, the fuel flow path in the metering valve may be the reverse of the flow path described in the present embodiment. Specifically, the fuel flow path is reversed so that the fuel flows in from the outlet ports 62 and 63 and flows out from the inlet port 61 via the concave groove 72, the through hole 73, and the valve body passage 71. .

  Next, the effect when the metering valve 40 of this embodiment is applied to the fuel injection pump 4 used in the common rail fuel injection system 1 will be described with reference to FIGS. 1 and 6. FIG. 6 is a diagram showing the relationship between the current applied to the coil 85 of the metering valve 40 and the pumping amount per rotation of the plunger pump 24.

  As shown in FIG. 1, the feed pump 23 sucks fuel from the fuel tank 6 and sends it to the metering valve 40 via the fuel flow path 48. The metering valve 40 adjusts the opening areas of the first and second outlet ports 62 and 63 based on the pumping amount determined by the ECU 7. The flow rate of the fuel that has flowed into the metering valve 40 from the fuel flow path 48 is adjusted by the first and second outlet ports 62 and 63 whose opening areas are adjusted, and flows out to the fuel supply flow paths 50 and 51. The fuel metered by the metering valve 40 flows into the pressurizing chambers 29 and 30 through the fuel supply passages 50 and 51 and the suction valves 41 and 42 together with the suction stroke of the plunger pump 24. Then, the process proceeds to the compression stroke, and the fuel in the pressurizing chambers 29 and 30 is pressurized and fed to the common rail 3.

  As shown in FIG. 6, even if the current applied to the metering valve 40 is the same, in other words, even if the position of the spool valve 70 of the metering valve 40 is the same, the engine operating state (engine speed) Changes, the pumping amount to the common rail 3 also changes. The amount of change in the pump pumping amount of the fuel injection pump 4 per unit current applied to the metering valve 40 is larger when the engine is operating in the low speed range than when the engine is operating in the high speed range. . This is because the suction stroke time of the plunger pump 24 is longer in the low rotation range, and a larger amount of fuel delivered from the metering valve 40 can be sucked.

  In order to improve the controllability of the pumping amount in the low rotation region, it is necessary to reduce the amount of change in the pumping amount in this region. The change in the pump pumping amount indicated by the one-dot chain line in FIG. 6 is a change in the pump pumping amount in the low rotation range when the metering valve of the comparative example is installed in the fuel injection pump 4. On the other hand, the change in the pumping amount indicated by the solid line is the change in the pumping amount in the low rotation range when the metering valve 40 of this embodiment is installed in the fuel injection pump 4.

  The pump pumping amount Δq per unit current Δi applied to the metering valve is the pump pumping amount Δq0 in the comparative example, and is the pump pumping amount Δq1 in the present embodiment. As shown in FIG. 6, the pump pumping amount Δq1 is smaller than the pump pumping amount Δq0. Thereby, by installing the metering valve 40 of the present embodiment in the fuel injection pump 4, it is possible to improve the controllability of the pump pumping amount in the low rotation range. This is particularly effective during idle operation where the engine speed is very low and a large pumping amount is not required.

(Second Embodiment)
Next, a metering valve according to a second embodiment of the present invention will be described with reference to FIGS. In addition, the same function thing as 1st Embodiment attaches | subjects the same name and code | symbol. Here, only the feature points different from the first embodiment will be described. FIG. 7 is a cross-sectional view of the metering valve 40 according to the present embodiment. The metering valve 40 of this embodiment is different from the metering valve of the first embodiment in that the opening described in the claims is formed in the spool valve 70.

  As shown in FIG. 7, the valve body 60 is formed with an inlet port 61 as a passage hole and first and second outlet ports 62a and 63a. The first and second outlet ports 62a and 63a have the same shape as the first and second outlet ports 620 and 630 of the comparative example shown in FIG. The locations of these ports 62a and 63a are the same as those in the comparative example. These correspond to the third communication passage according to claim 8. On the other hand, a valve body passage 71 is formed in the spool valve 70 in the axial direction thereof. A first concave groove 72a and a second concave groove 72b are formed on the outer wall of the spool valve 70, and further, a valve body passage 71 and the first and second concave grooves 72a and 72b are connected to the bottom portion thereof. A first through hole 73a and a second through hole 73b are formed.

  In the present embodiment, the first and second concave grooves 72a and 72b respectively correspond to the openings described in the claims, and have widths larger than the widths of the first and second outlet ports 62a and 63a, respectively. This is a substantially square groove. The valve body passage 71, the first through hole 73a, and the second through hole 73b correspond to the second communication passage according to claim 8.

  Next, the relationship between the first and second concave grooves 72a and 72b and the first and second outlet ports 62a and 63a will be described with reference to FIG. FIG. 8A shows the relationship between the first groove 72a and the first outlet port 62a, and FIG. 8B shows the relationship between the second groove 72b and the second outlet port 63a. FIG.

  As shown in FIGS. 8A and 8B, the first and second concave grooves 72a and 72b are in positions where they communicate with the first and second outlet ports 62a and 63a, respectively, when the spool valve 70 moves. Is formed. The widths of the first and second concave grooves 72a and 72b are both larger than the widths of the first and second outlet ports 62a and 63a. The axial length of the first concave groove 72a is the same as or longer than that of the second concave groove 72b. The positions of the end portions of the first and second concave grooves 72a and 72b on the inlet port 61 side with respect to the spool valve 70 are substantially the same position.

  The fuel flowing in from the inlet port 61 reaches the first and second concave grooves 72a and 72b through the valve body passage 71 and the first and second through holes 73a and 73b. When a current is applied to the coil 85, the spool valve 70 moves in the direction of the stator 84. Then, first, the first groove 72a and the first outlet port 62a communicate with each other, and the fuel in the groove 72a flows out from the outlet port 62a. Next, the second groove 72b communicates with the second outlet port 63a, and the fuel in the groove 72b flows out from the outlet port 63a.

  Thereby, the effect similar to 1st Embodiment can be acquired. The metering valve 40 of the present embodiment is of a normally closed type, but it is needless to say that the same effects as those of the first embodiment can be obtained even with a normally open type.

  Further, the metering valve 40 of the present embodiment is provided with guide means described in the claims for preventing the spool valve 70 from rotating in the circumferential direction inside the valve body 60 as shown in FIG. Yes. FIG. 9 is a cross-sectional view taken along the line IX-IX in FIG. The guide means includes a valve body side guide groove 120 formed in the axial direction, a spool valve side guide groove 121 formed in the axial direction, and a prismatic guide member 122 provided in a space between both guide grooves 120, 121. It is configured. Thereby, it is possible to prevent the spool valve 70 from rotating in the circumferential direction inside the valve body 60, and when the spool valve 70 is moved in the axial direction, both the concave grooves 72a and 72b are securely connected to both the outlet ports 62a and 63a. Can communicate.

1 is a system diagram of a common rail fuel injection system for a diesel engine to which a metering valve according to a first embodiment of the present invention is applied. It is sectional drawing of the metering valve by 1st Embodiment of this invention. It is a top view of the 1st, 2nd exit port of the metering valve of FIG. FIG. 4 is a flow rate characteristic diagram showing the relationship between the magnitude of current applied to the coil of the metering valve of FIG. 3 and the flow rate of fuel passing through the metering valve. It is a flow rate characteristic figure showing the relation between the size of the current applied to the coil of the normally open type metering valve and the flow rate of the fuel passing through the metering valve. FIG. 4 is a pressure feed characteristic diagram of a fuel injection pump when the metering valve of FIG. 3 is applied to a common rail fuel injection system. It is sectional drawing of the metering valve by 2nd Embodiment of this invention. It is a top view of the spool valve of the metering valve of FIG. It is sectional drawing of the IX-IX cross section of the metering valve of FIG. It is a top view of the exit port of the metering valve as a comparative example. It is a flow characteristic figure showing the relation between the size of the current applied to the coil of the metering valve as a comparative example, and the flow rate of the fuel passing through the metering valve.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Fuel injection system, 2 Injector, 3 Common rail, 4 Fuel injection pump, 5 Fuel filter, 6 Fuel tank, 7 Electronic control unit (ECU), 8 Pressure sensor, 20 Pump housing, 21, 22 Cylinder head, 23 Feed pump, 24 Plunger pump, 25, 26 Plunger, 29, 30 Pressurizing chamber, 31 Cam shaft, 32 Cam, 33 Shoe, 40 Metering valve, 41, 42 Suction valve, 43 Discharge valve, 44 Regulating valve, 48, 49 Fuel Flow path, 50, 51 Fuel supply path, 52 Pump cam chamber, 60 Valve body, 61 Inlet port (passage hole), 62 First outlet port (opening), 63 Second outlet port (opening), 64 First slit Part (first region of the opening), 65 Slit portion (first region of opening), 66 First wide portion (second region of opening), 67 Second wide portion (second region of opening), 70 Spool valve (valve element), 71 Valve element Passage (first communication passage, second communication passage), 72 concave groove (first communication passage), 73 through hole (first communication passage), 80 electromagnetic drive section (electromagnetic drive means), 81 housing, 82 connector, 83 electrode, 84 stator, 85 coil, 86 yoke, 87 flange, 90 spring (biasing means), 100 O-ring, 110 stopper, 62a first outlet port (third communication path), 63a second Outlet port (third communication path), 72a First groove (opening), 72b Second groove (opening), 73a First through-hole (second communication path), 73b Second through-hole (first 2 passages , 120 valve body side guide groove (guide means) 121 spool valve side guide groove (guide means), 122 guide member (guide means)

Claims (10)

A metering valve that is installed in the middle of the flow path, adjusts the opening area of the opening, and adjusts the flow rate of the fluid flowing through the flow path,
A valve body for adjusting the opening area of the opening,
Biasing means for biasing the valve body in a predetermined direction;
An electromagnetic drive means for attracting the valve body against the urging force of the urging means when energized to the coil;
The opening comprises at least two openings that open in a low flow rate region,
In the low flow rate region, one of the openings is opened before the other opening.   The metering valve according to claim 1, wherein the length of the one opening is longer than the length of the other opening. The opening has a first region used in the low flow region and a second region used in the high flow region,
3. The metering valve according to claim 1, wherein a width of the opening in the first region is smaller than a width of the opening in the second region.   4. The metering valve according to claim 3, wherein the width of the opening in the first region is substantially the same from a tip of the first region to a boundary portion with the second region. When energization of the coil is stopped,
5. The valve body according to claim 1, wherein the valve body is moved to a position at which the one opening and the other opening are fully closed by the urging force of the urging means. The metering valve according to any one of the above. When energization of the coil is stopped,
The valve body is moved to a position where the one opening and the other opening are fully opened by the urging force of the urging means. A metering valve according to claim 1. The valve body is accommodated in a cylindrical valve body having a passage hole at one end so as to be relatively movable in the axial direction.
The valve body is formed with the one opening and the other opening,
7. The valve body according to claim 1, wherein a first communication passage is formed in which the one opening or the other opening and the passage hole communicate with each other. The metering valve according to item. The valve body is accommodated in a cylindrical valve body having a passage hole at one end so as to be relatively movable in the axial direction.
The valve body is formed with the one opening and the other opening, and the second communication path in which the one opening and the other opening and the passage hole communicate with each other.
The valve body is formed with a third communication passage in which the one opening and the other opening communicate with the outside of the valve body, or The metering valve according to any one of claims 4 to 6.   The metering valve according to claim 8, wherein the valve body and the valve body are provided with guide means for guiding the valve body in an axial direction of the valve body. A housing in which a pressurizing chamber in which fuel is pressurized is formed;
A movable member which is installed in the housing so as to be reciprocally movable and pressurizes the fuel sucked into the pressurizing chamber;
Drive means for driving the movable member;
The metering valve according to any one of claims 1 to 9, wherein a flow rate of fuel sent to the pressurizing chamber is adjusted.
A fuel injection pump comprising:

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