JP5293237B2 - Metering valve for fuel injection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To create discharge characteristic that a discharge amount is rapidly varied relative to a variation amount of electro-magnetic attraction force at intermediate loading while suppressing variation of a discharge amount of a supply pump at a low load area. <P>SOLUTION: In the metering valve, an opening area of a port 903 through which the fuel fed from a low pressure pump to a high pressure pump passes is varied by a valve element 92. A first spring 94 and a second spring 95 for urging the valve element 92 toward valve-closing are arranged in series. At the area (low load area) where the electro-magnetic attraction force is a predetermined value or less, since a deflection amount of the only first spring 94 is varied and spring constant is relatively large, a movement amount of the valve element 92 relative to the variation amount of the electro-magnetic attraction force becomes small and variation of the discharge amount of the supply pump is suppressed. At the area (intermediate-high load area) where the electro-magnetic attraction force exceeds a predetermined value, since deflection amounts of the two springs 94, 95 are varied together and the spring constant is relatively small, the movement amount of the valve element 92 relative to the variation amount of the electro-magnetic attraction force becomes large and the variation amount of the discharge amount can be increased. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a fuel injection system metering valve that adjusts the flow rate of fuel sent from a low-pressure pump to a high-pressure pump.

  Conventionally, in a common rail fuel injection system known as, for example, a diesel engine fuel injection system, the pressure of the fuel is increased by a supply pump to supply the high pressure fuel to the common rail, and the high pressure fuel stored in the common rail is passed through the injector. The engine is configured to inject into the combustion chamber of each cylinder of the engine, and during operation of the engine, fuel for the injection amount is supplied from the supply pump to the common rail.

  The above supply pump is a low-pressure pump that supplies fuel in the fuel tank to the high-pressure pump, a high-pressure pump that pressurizes the fuel to increase the pressure and supplies it to the common rail, and a metering that adjusts the flow rate of fuel sent from the low-pressure pump to the high-pressure pump It has a valve. And the quantity of the fuel discharged from a high pressure pump is adjusted by adjusting the quantity of the fuel supplied to a high pressure pump from a low pressure pump by a metering valve.

  The metering valve includes a valve body having a port through which fuel sent from the low pressure pump to the high pressure pump passes, a valve body slidably inserted into the valve body to change the opening area of the port, and an electromagnetic suction force Drive means for driving the valve body in the valve opening direction, and a spring for biasing the valve body in the valve closing direction. And by controlling the electromagnetic attraction force and controlling the relative position of the valve body with respect to the valve body, the opening area of the port is adjusted, and the amount of fuel supplied to the high pressure pump is adjusted. (For example, refer to Patent Document 1).

Japanese Patent No. 3887817

  By the way, in order to make the exhaust performance at the time of low load and the output at the time of high load compatible in the vehicle engine, the supply pump is required to have a discharge characteristic of a low discharge amount at a low load and a high discharge amount at a high load. Further, at the time of medium load, a discharge characteristic is required in which the discharge amount changes rapidly with respect to the change amount of the electromagnetic attractive force. And in the metering valve, the magnitude of the electromagnetic attraction force and the displacement of the valve body are approximately proportional, so the port of the valve body is an irregular port and the relationship between the electromagnetic attraction force and the opening area of the port is set appropriately By doing so, the discharge characteristic according to the vehicle requirement is obtained.

  However, as the supply pump increases in discharge volume with the development of models for high-output vehicles, the size of the atypical port and the abrupt area change of the atypical port with respect to the amount of change in electromagnetic attraction force are required. Due to the restrictions on the structure of the body and the processing of the irregular port, the degree of freedom in adapting the discharge characteristics is almost lost.

  Here, if the amount of displacement of the valve body with respect to the amount of change in electromagnetic attraction force is increased by reducing the spring force, the change in the area of the port with respect to the amount of change in electromagnetic attraction force will increase. It can correspond to characteristics. However, in this case, since the amount of change in the area of the port with respect to the amount of change in the electromagnetic attractive force becomes large even in a low load region such as idling, the fluctuation in the discharge amount of the supply pump in the low load region becomes large. The engine rotation at idling becomes unstable.

  The present invention has been made in view of the above points, and an object of the present invention is to make it possible to meet the required characteristics in the middle and high load regions while suppressing fluctuations in the discharge amount of the supply pump in the low load region.

  In order to achieve the above object, according to the first aspect of the present invention, a common rail (1) for storing high-pressure fuel injected into a cylinder of an internal combustion engine, and a high-pressure pump (7) for pumping high-pressure fuel to the common rail (1) are provided. ) And a low pressure pump (8) for supplying the fuel in the fuel tank (5) to the high pressure pump (7), and the fuel sent from the low pressure pump (8) to the high pressure pump (7) In a metering valve for adjusting the flow rate of the valve body, the valve body (90) having a port (903) through which fuel sent from the low pressure pump (8) to the high pressure pump (7) passes is slidable in the valve body (90). And a drive means (96, 98, 99, 103, 104) for driving the valve body (92) in the valve opening direction by electromagnetic attraction force, and changing the opening area of the port (903). When, A first spring (94) is interposed between the first spring (94) for urging the body (92) in the valve closing direction and the valve body (92), and is arranged in series with the first spring (94). A second spring (95) for urging the valve body (92) in the valve closing direction, and in a region where the electromagnetic attractive force is a predetermined value or less, the two springs (94, 94, 95), in the region where only the first spring (94) bends and the electromagnetic attractive force exceeds a predetermined value, the amount of bending of the two springs (94, 95) depends on the magnitude of the electromagnetic attractive force. Both are configured to change.

  According to this, the combined spring of the two springs (94, 95) in the region where the electromagnetic attraction force exceeds the predetermined value than the spring constant of the first spring (94) in the region where the electromagnetic attraction force is less than the predetermined value. The constant is smaller.

  In a region where the electromagnetic attraction force is equal to or less than a predetermined value (corresponding to a low load region), the spring constant is relatively large. Therefore, the amount of movement of the valve element (92) with respect to the amount of change in the electromagnetic attraction force is small, and as a result The change in the area of the port (903) with respect to the amount of change in suction force is reduced, and fluctuations in the discharge amount of the supply pump can be suppressed.

  In the region where the electromagnetic attractive force exceeds a predetermined value (corresponding to medium / high load), the spring constant is relatively small, so the amount of movement of the valve element (92) with respect to the amount of change in the electromagnetic attractive force increases. As a result, the change in the area of the port (903) with respect to the amount of change in the electromagnetic attraction force increases, so that it is possible to meet the required characteristic of increasing the amount of change in the discharge amount with respect to the amount of change in the electromagnetic attraction force.

  According to a second aspect of the present invention, in the metering valve for a fuel injection system according to the first aspect, the valve is sandwiched between the first spring (94) and the second spring (95) and is attached to the valve body (90). An intermediate member (93) slidably inserted, and the first spring (94) is sandwiched between the valve body (92) and the intermediate member (93), and is a movement regulating surface formed on the valve body (90). When the intermediate member (93) comes into contact with (902), the movement of the intermediate member (93) toward the valve body closing direction is restricted, and in a region where the electromagnetic attractive force is a predetermined value or less, the intermediate member (93) The state in which the state of contact with the movement restriction surface (902) is maintained and the intermediate member (93) is configured to be separated from the movement restriction surface (902) in a region where the electromagnetic attractive force exceeds a predetermined value. To do.

  According to this, in a region where the electromagnetic attractive force is not more than a predetermined value, the amount of displacement of the valve body (92) with respect to the amount of change of the electromagnetic attractive force can be reduced by changing the amount of deflection of only the first spring (94). At the same time, in the region where the electromagnetic attractive force exceeds a predetermined value, the amount of displacement of the valve body (92) with respect to the amount of change in the electromagnetic attractive force can be increased by changing the amount of deflection of the two springs (94, 95). .

  In the third aspect of the invention, the common rail (1) for storing the high-pressure fuel injected into the cylinder of the internal combustion engine, the high-pressure pump (7) for feeding the high-pressure fuel to the common rail (1), and the fuel tank (5 ) Is used in a fuel injection system including a low-pressure pump (8) for supplying the fuel in the high-pressure pump (7) to adjust the flow rate of the fuel sent from the low-pressure pump (8) to the high-pressure pump (7). In the valve, a valve body (90) having a port (903) through which fuel sent from the low pressure pump (8) to the high pressure pump (7) passes, and a port ( 903) a valve body (92) for changing the opening area, drive means (96, 98, 99, 103, 104) for driving the valve body (92) in the valve opening direction by electromagnetic attraction, and a valve body (92) ) For valve closing A first spring (94) is interposed between the urging first spring (94) and the valve body (92), and is arranged in series with the first spring (94), and the valve body (92) is closed. A second spring (95) biased in the direction, and the relationship between the spring constant ka of the first spring (94) and the spring constant kb of the second spring (95) is ka> kb, and the electromagnetic attractive force is In the region below the predetermined value, the second spring (95) is maintained in an initial load state, and the amount of bending of the first spring (94) changes according to the magnitude of the electromagnetic attraction force. In the region where the attractive force exceeds a predetermined value and is equal to or less than the initial load of the second spring (95), the amount of bending of the two springs (94, 95) does not change, and the electromagnetic attractive force is the second spring (95). In the region exceeding the initial load of Characterized in that it is configured such that the second spring (95) the amount of deflection of only one of the attraction two depending on the size of the spring (94, 95) is changed.

  According to this, in a region where the electromagnetic attractive force is equal to or less than a predetermined value (corresponding to a low load region), the first spring (94) having a relatively large spring constant opposes the electromagnetic attractive force. The displacement amount of the valve body (92) with respect to is reduced, and consequently the change in the area of the port (903) with respect to the change amount of the electromagnetic attraction force is reduced, and the fluctuation of the discharge amount of the supply pump can be suppressed.

  Further, in the region where the electromagnetic attractive force exceeds the initial load of the second spring (95) (corresponding to medium / high load), the second spring (95) having a relatively small spring constant opposes the electromagnetic attractive force. The displacement of the valve element (92) with respect to the amount of change in electromagnetic attraction force increases, and as a result, the change in area of the port (903) with respect to the amount of change in electromagnetic attraction force increases. It is possible to meet the required characteristics of increasing the amount of change.

  Furthermore, in a region where the electromagnetic attractive force exceeds a predetermined value and is equal to or less than the initial load of the second spring (95), the valve element (92) does not move even if the electromagnetic attractive force changes. Therefore, if the discharge amount of the supply pump is set to the required discharge amount at idling when the electromagnetic attraction force exceeds the predetermined value and is in the region below the initial load of the second spring (95), The rotation of the internal combustion engine can be stabilized.

  According to a fourth aspect of the present invention, in the metering valve for the fuel injection system according to the third aspect, the valve body (90) is sandwiched between the first spring (94) and the second spring (95). An intermediate member (93) slidably inserted, and the first spring (94) is sandwiched between the valve body (92) and the intermediate member (93), and is a movement regulating surface formed on the valve body (90). When the intermediate member (93) comes into contact with (902), the movement of the intermediate member (93) toward the valve body closing direction is restricted, and in a region where the electromagnetic attractive force is a predetermined value or less, the intermediate member (93) In a region where the state of contact with the movement restricting surface (902) is maintained and the electromagnetic attractive force exceeds a predetermined value and is equal to or less than the initial load of the second spring (95), the intermediate member (93) is moved to the movement restricting surface (902). Is in contact with the In the region where the valve body (92) and the intermediate member (93) are in contact with each other and the electromagnetic attraction force exceeds the initial load of the second spring (95), the valve body (92) and the intermediate member (93) are in the middle. The state in which the member (93) abuts is maintained, and the intermediate member (93) is configured to be separated from the movement restricting surface (902).

  According to this, in a region where the electromagnetic attractive force is not more than a predetermined value, the amount of displacement of the valve body (92) with respect to the amount of change of the electromagnetic attractive force can be reduced by changing the amount of deflection of only the first spring (94). At the same time, in the region where the electromagnetic attractive force exceeds the initial load of the second spring (95), only the amount of deflection of the second spring (95) is changed to change the displacement of the valve element (92) with respect to the amount of change of the electromagnetic attractive force. Can be bigger. Further, in a region where the electromagnetic attractive force exceeds a predetermined value and is equal to or less than the initial load of the second spring (95), the valve element (92) can be prevented from moving even if the electromagnetic attractive force changes.

  According to a fifth aspect of the present invention, in the metering valve for a fuel injection system according to any one of the first to fourth aspects, the initial load of the first spring (94) is Pa and the second spring (95) When the initial load is Pb, Pa <Pb.

  According to this, in the region where the electromagnetic attractive force is a predetermined value or less, it is possible to change the deflection amount of only the first spring (94).

  In addition, the code | symbol in the bracket | parenthesis of each means described in a claim and this column shows the correspondence with the specific means as described in embodiment mentioned later.

It is a figure showing the whole fuel injection system composition provided with the metering valve concerning a 1st embodiment of the present invention. It is sectional drawing which shows the specific structure of the metering valve 9 which concerns on 1st Embodiment. It is A arrow directional view of the port 903 in the metering valve 9 of FIG. It is a characteristic view which shows the relationship between the electromagnetic attraction force in the metering valve 9 which concerns on 1st Embodiment, and the displacement amount of the valve body 92. FIG. It is a characteristic view which shows the relationship between the electric current supplied to the coil 103 in the metering valve 9 which concerns on 1st Embodiment, and the discharge amount of the supply pump P. FIG. It is sectional drawing which shows the structure of the principal part of the metering valve which concerns on 2nd Embodiment of this invention. It is a characteristic view which shows the relationship between the electromagnetic attraction force in the metering valve 9 which concerns on 2nd Embodiment, and the displacement amount of the valve body 92. FIG. It is a characteristic view which shows the relationship between the electric current supplied to the coil 103 and the discharge amount of the supply pump P in the metering valve 9 which concerns on 2nd Embodiment. It is sectional drawing which shows the structure of the principal part of the metering valve which concerns on the reference example of this invention. It is a characteristic view which shows the relationship between the electromagnetic attraction force in the metering valve 9 which concerns on a reference example , and the displacement amount of the valve body 92. FIG. It is a characteristic view which shows the relationship between the electric current supplied to the coil 103 in the metering valve 9 which concerns on a reference example , and the discharge amount of the supply pump P. FIG. It is sectional drawing which shows the modification of the metering valve which concerns on a reference example .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 1 is a diagram illustrating an overall configuration of a fuel injection system including a metering valve according to the first embodiment.

  As shown in FIG. 1, the fuel injection system includes a pressure accumulator 1 that stores high-pressure fuel, and a plurality of injectors 2 are connected to the pressure accumulator 1. The injector 2 is controlled by a control device (hereinafter referred to as ECU) 3 and opens at a predetermined time for a predetermined period, and the high pressure fuel supplied from the pressure accumulator 1 is supplied to each cylinder of the diesel engine (not shown). To spray. Here, only the injector 2 corresponding to one of the four-cylinder engines is shown, and illustration of the injectors corresponding to the other cylinders is omitted.

  The high pressure fuel stored in the pressure accumulator 1 is supplied from the supply pump P via the high pressure passage 4. The supply pump P pressurizes the fuel and discharges it to the accumulator 1, the low-pressure pump 8 that supplies the fuel sucked from the fuel tank 5 through the filter 6 to the high-pressure pump 7, and the low-pressure pump 8. A metering valve 9 for adjusting the flow rate of the fuel supplied to the high-pressure pump 7 is provided. The high-pressure pump 7 is a pump of a type in which the fuel discharge amount is adjusted by adjusting the fuel intake amount by the metering valve 9. The high pressure pump 7 and the low pressure pump 8 are driven by the engine.

  The ECU 3 includes a known microcomputer including a CPU, ROM, RAM, and the like (not shown), and performs arithmetic processing according to a program stored in the microcomputer. Various information such as a signal related to the fuel pressure (so-called common rail pressure) in the accumulator 1, the engine speed, and the accelerator opening is input to the ECU 3 from time to time.

  The ECU 3 calculates the optimal injection timing and injection amount (injection period) according to the operating state of the engine and the vehicle, and controls the valve opening timing and valve opening period of each injector 2. Further, the ECU 3 calculates the target discharge amount of the supply pump P, outputs a control signal to the metering valve 9 of the supply pump P, and controls the discharge amount of the supply pump P, thereby controlling the fuel pressure in the accumulator 1. To control.

  2 is a cross-sectional view showing a specific configuration of the metering valve 9 of FIG. 1, and FIG. 3 is a view of the port 903 in the metering valve 9 of FIG.

  As shown in FIG. 2, the metering valve 9 includes a metal cylindrical valve body 90. The valve body 90 includes a columnar first sliding hole 900 and the first sliding hole. A second sliding hole 901 having a diameter larger than 900 and a columnar shape is formed in series along the axial direction. At the boundary between the first sliding hole 900 and the second sliding hole 901, a step 902 as a movement restricting surface is formed.

  A ring-shaped spring receiver 91 having a fuel passage hole 910 is press-fitted into the opening end portion of the second sliding hole 901 in the valve body 90. The fuel passage hole 910 is connected to the low pressure pump 8, and the fuel sent from the low pressure pump 8 is introduced into the second sliding hole 901 through the fuel passage hole 910.

  A port 903 that penetrates the peripheral wall of the first sliding hole 900 is formed on the peripheral wall of the first sliding hole 900 in the valve body 90. The port 903 is connected to the high-pressure pump 7, and fuel introduced from the low-pressure pump 8 into the valve body 90 is sent to the high-pressure pump 7 via the port 903. Further, as shown in FIG. 3, the port 903 has a shape that is elongated in the axial direction with a constant width.

  A metal cylindrical valve element 92 that changes the opening area of the port 903 is slidably inserted into the first sliding hole 900 in the valve body 90. A valve body groove 920 that can communicate with the port 903 is formed in an annular shape on the outer peripheral side of the valve body 92, and the valve body groove 920 and the inside of the valve body 92 are connected to the inner peripheral side of the valve body 92. A valve body hole 921 for communication is formed. The inside of the valve body 92 is always in communication with the fuel passage hole 910. Then, the communication area between the valve body groove 920 and the port 903 changes according to the movement position of the valve body 92, thereby adjusting the opening area of the port 903.

  A metal stepped cylindrical intermediate member 93 is slidably inserted into the valve body 90. The intermediate member 93 includes a cylindrical tube portion 930 that is slidably inserted into the first sliding hole 900. A ring-shaped first flange 931 that protrudes radially outward is formed on the outer peripheral side of the end portion of the cylindrical portion 930, and the first flange 931 is slid into the second sliding hole 901. It is inserted movably and can contact the stepped portion 902. Further, a ring-shaped second collar portion 932 that protrudes radially inward is formed on the inner peripheral side of the cylindrical portion 930.

  A first spring 94 made of a compression coil spring is sandwiched between the valve body 92 and the second flange portion 932 of the intermediate member 93. The first spring 94 biases the valve body 92 in the valve closing direction, that is, in the direction in which the opening area of the port 903 is reduced.

  A second spring 95 made of a compression coil spring is sandwiched between the spring receiver 91 and the second flange 932 of the intermediate member 93. In other words, the intermediate member 93 is sandwiched between the first spring 94 and the second spring 95. The second spring 95 is disposed in series with the first spring 94 with the first spring 94 interposed between the second spring 95 and the valve body 92. The second spring 95 urges the valve body 92 in the valve closing direction via the intermediate member 93 and the first spring 94.

  The metering valve 9 is provided with a cylindrical holder 96 with a flange made of magnetic metal. The first sliding hole 900 side of the valve body 90 is inserted into one end side of the holder 96, and one end side end portion of the holder 96 is caulked to fix the valve body 90. A bottomed cylindrical stator core 98 made of magnetic metal is joined to the other end side of the holder 96 via a ring-like joining ring 97 made of nonmagnetic metal.

  A cylindrical armature 99 made of magnetic metal is inserted into the stator core 98. A cylindrical rod 100 made of nonmagnetic metal is press-fitted into the armature 99, and one end of the rod 100 is in contact with the valve body 92. Both ends of the rod 100 are supported by bearings 101, so that the rod 100 and the armature 99 are slidable within the stator core 98. One of the two bearings 101 is press-fitted into the stator core 98, and the other is press-fitted into a metal cylindrical stopper 102. The stopper 102 is sandwiched between the holder 96 and the valve body 90.

  A coil 103 that forms a magnetic field when energized is disposed on the outer peripheral side of the stator core 98. The outer peripheral side of the coil 103 is covered with a cylindrical yoke 104 made of magnetic metal.

  The holder 96, the stator core 98, the armature 99, and the yoke 104 form a magnetic circuit when the coil 103 is energized. An electromagnetic attraction force is generated by energization of the coil 103, and the armature 99 and the rod 100 are driven toward the valve body 92 (that is, in the valve opening direction) by the electromagnetic attraction force. The holder 96, the stator core 98, the armature 99, the yoke 104, and the coil 103 constitute drive means of the present invention.

  Here, the relationship between the initial load Pa of the first spring 94 and the initial load Pb of the second spring 95 is Pa <Pb. FIG. 2 shows a state in which the coil 103 is not energized, and since Pa <Pb, the first flange portion 931 of the intermediate member 93 comes into contact with the stepped portion 902 of the valve body 90 and the intermediate member 93 Movement in the direction of valve closing is restricted. Further, when the coil 103 is not energized, a gap L in the valve body moving direction is provided between the valve body 92 and the intermediate member 93. When the coil 103 is not energized, the valve element 92 is biased to the initial position by the first spring 94, and the opening area of the port 903 is minimized.

  Even when the electromagnetic attraction force is controlled to the maximum value, the initial load Pa of the first spring 94, the initial load Pb of the second spring 95, the first load so that the valve body 92 and the intermediate member 93 do not come into contact with each other. A spring constant ka of the spring 94, a spring constant kb of the second spring 95, and a gap L are set.

  In the metering valve 9 configured as described above, when a voltage is applied to the coil 103, the armature 99 is attracted to the valve body 92 side (that is, the anti-stator core side) by electromagnetic attraction, and the valve body 92 is attracted to the armature 99 and the rod 100. It is pushed and moves in the valve opening direction. The electromagnetic attraction force is controlled by controlling the current supplied to the coil 103 by the ECU 3, and the position of the valve element 92 is continuously changed according to the electromagnetic attraction force. The opening area is adjusted according to the value. Specifically, as the current supplied to the coil 103 increases, the opening area of the port 903 increases, the flow rate of the fuel supplied to the high pressure pump 7 increases, and the pressure from the high pressure pump 7 to the accumulator 1 increases. The amount of fuel discharged increases. Incidentally, the current supplied to the coil 103 and the electromagnetic attractive force are substantially proportional.

  Here, FIG. 4 is a characteristic diagram showing the relationship between the electromagnetic attraction force (= total spring force of the first spring 94 and the second spring 95) in the metering valve 9 configured as described above and the displacement amount of the valve body 92. is there. FIG. 5 is a characteristic diagram showing the relationship between the current supplied to the coil 103 and the discharge amount of the supply pump P in the metering valve 9 configured as described above.

  In a region where the electromagnetic attractive force is equal to or greater than the initial load Pa of the first spring 94 and equal to or smaller than the initial load Pb of the second spring 95, the amount of deflection of the first spring 94 (ie, the spring force) as the electromagnetic attractive force increases. On the other hand, the first flange portion 931 of the intermediate member 93 remains in contact with the stepped portion 902 of the valve body 90, and the amount of bending of the second spring 95 does not change.

  In a region where the electromagnetic attractive force exceeds the initial load Pb of the second spring 95, the amount of bending of the first spring 94 increases as the electromagnetic attractive force increases, and the first flange portion 931 of the intermediate member 93 is connected to the valve body 90. The amount of bending of the second spring 95 is also increased away from the step portion 902. Thus, the combined spring constant k when the amount of deflection of both the first spring 94 and the second spring 95 changes is given by k = (ka · kb) / (ka + kb), and the spring of the first spring 94 It becomes smaller than the constant ka.

  Therefore, as shown in FIGS. 4 and 5, in the region where the electromagnetic attractive force is not less than the initial load Pa of the first spring 94 and not more than the initial load Pb of the second spring 95 (corresponding to a low load region), Since the spring constant is large, the displacement amount of the valve element 92 and the area change amount of the port 903 with respect to the change amount of the electromagnetic attraction force are reduced, so that the fluctuation of the discharge amount of the supply pump P can be suppressed.

  Further, in the region where the electromagnetic attractive force exceeds the initial load Pb of the second spring 95 (corresponding to the middle / high load), the spring constant is relatively small, so the displacement amount of the valve element 92 with respect to the change amount of the electromagnetic attractive force and The amount of change in the area of the port 903 increases, and therefore, the amount of change in the discharge amount of the supply pump P relative to the amount of change in the current supplied to the coil 103 can be increased.

(Second Embodiment)
A second embodiment of the present invention will be described. FIG. 6 is a cross-sectional view showing the configuration of the main part of the metering valve according to the second embodiment.

  In the first embodiment, the valve body 92 is continuously displaced in accordance with the change of the electromagnetic suction force. However, in this embodiment, a region where the valve body 92 is not displaced even if the electromagnetic suction force is changed is provided. ing. Since other aspects are the same as those in the first embodiment, only different parts will be described.

  In the present embodiment, the relationship between the spring constant ka of the first spring 94 and the spring constant kb of the second spring 95 is ka> kb.

  Further, in a region where the electromagnetic attractive force exceeds a certain value, the valve body 92 and the intermediate member 93 come into contact with each other. Specifically, the load Pa ′ (hereinafter referred to as the maximum load of the first spring 94) Pa ′ in a state where the valve body 92 and the intermediate member 93 are in contact with each other is Pa ′ = Pa + ka · L. The initial load Pa of the first spring 94, the initial load Pb of the second spring 95, the spring constant ka of the first spring 94, and the gap L are set so that Pa ′ <Pb.

  FIG. 7 is a characteristic diagram showing the relationship between the electromagnetic attractive force in the metering valve 9 configured as described above and the amount of displacement of the valve element 92, and FIG. 5 is supplied to the coil 103 in the metering valve 9 configured as described above. It is a characteristic view which shows the relationship between an electric current and the discharge amount of the supply pump P.

  In a region where the electromagnetic attraction force is not less than the initial load Pa of the first spring 94 and not more than the maximum load Pa ′ of the first spring 94, the amount of deflection of the first spring 94 (ie, the spring force) as the electromagnetic attraction force increases. On the other hand, the first flange portion 931 of the intermediate member 93 remains in contact with the stepped portion 902 of the valve body 90, and the amount of bending of the second spring 95 does not change.

  When the electromagnetic attractive force reaches the maximum load Pa ′ of the first spring 94, the valve body 92 and the intermediate member 93 come into contact with each other. In a region where the electromagnetic attractive force exceeds the maximum load Pa ′ of the first spring 94 and is equal to or less than the initial load Pb of the second spring 95, the valve body 92 and the intermediate member 93 come into contact with each other, and the first of the intermediate member 93 The state in which the flange portion 931 is in contact with the stepped portion 902 of the valve body 90 is maintained. Therefore, in this region, the amount of bending of the first spring 94 and the second spring 95 does not change.

  In a region where the electromagnetic attractive force exceeds the initial load Pb of the second spring 95, the state in which the valve body 92 and the intermediate member 93 are in contact with each other is maintained, and the amount of bending of the first spring 94 does not change. 93, the first flange portion 931 moves away from the stepped portion 902 of the valve body 90, and the amount of bending of the second spring 95 increases as the electromagnetic attractive force increases.

  Therefore, as shown in FIGS. 7 and 8, in the region where the electromagnetic attractive force is not less than the initial load Pa of the first spring 94 and not more than the maximum load Pa ′ of the first spring 94 (corresponding to a low load region), Since the first spring 94 having a large spring constant opposes the electromagnetic attraction force, the displacement amount of the valve body 92 and the area change amount of the port 903 with respect to the change amount of the electromagnetic attraction force are reduced. Fluctuations can be suppressed.

  Further, in a region where the electromagnetic attractive force exceeds the initial load Pb of the second spring 95 (corresponding to a medium / high load), the second spring 95 having a relatively small spring constant opposes the electromagnetic attractive force. The amount of displacement of the valve body 92 and the amount of change in the area of the port 903 with respect to the amount of change in the flow rate increase, and accordingly, the amount of change in the discharge amount of the supply pump P with respect to the amount of change in the current supplied to the coil 103 can be increased.

  Further, in a region where the electromagnetic attractive force exceeds the maximum load Pa ′ of the first spring 94 and is equal to or less than the initial load Pb of the second spring 95, the valve element 92 does not move even if the electromagnetic attractive force changes. As shown, a dead zone B in which the discharge amount of the supply pump P is constant occurs. Therefore, if the discharge amount of the supply pump P in the dead zone B is set to be the required discharge amount during idling, the rotation of the internal combustion engine during idling can be stabilized.

( Reference example )
Reference examples of the present invention will be described. FIG. 9 is a cross-sectional view showing a configuration of a main part of a metering valve according to a reference example . Although the normally closed type metering valve that is fully closed when not energized is shown in the first embodiment, this reference example is a normally open type metering valve that is fully opened when not energized. Since other aspects are the same as those in the first embodiment, only different parts will be described.

  As shown in FIG. 9, when the coil 103 (see FIG. 2) is not energized, the valve element 92 is biased to the initial position by the spring 110, and the opening area of the port 903 is maximized. When the coil 103 is energized, the valve element 92 is driven in the valve closing direction by the electromagnetic attractive force, and the opening area of the port 903 decreases.

  The second sliding hole 901 (see FIG. 2) of the valve body 90 is deleted, and the intermediate member 93 (see FIG. 2) is deleted. The spring 110 is sandwiched between the spring receiver 91 and the valve body 92. The spring 110 biases the valve body 92 in the opening direction, that is, in the direction in which the opening area of the port 903 is increased. The spring 110 is a conical coil spring having non-linear characteristics.

  Here, FIG. 10 is a characteristic diagram showing the relationship between the electromagnetic attraction force (= spring force of the spring 110) and the displacement amount of the valve body 92 in the metering valve 9 configured as described above. FIG. 11 is a characteristic diagram showing the relationship between the current supplied to the coil 103 in the metering valve 9 configured as described above and the discharge amount of the supply pump P (see FIG. 1).

  As shown in FIGS. 10 and 11, since the spring 110 having a nonlinear characteristic is used in the normally open type metering valve 9, the region A (high load) where the spring 110 has a small deflection and the port 903 has a large opening area. 2), the spring constant is relatively small, the amount of movement of the valve body 92 with respect to the amount of change in the electromagnetic attraction force is increased, and the area change of the port 903 with respect to the amount of change in the electromagnetic attraction force is increased. The amount of change in the discharge amount with respect to the amount of change in becomes large.

  In the region C (corresponding to a low load region) where the spring 110 is largely bent and the port 903 has a small opening area, the spring constant is relatively large. As a result, the change in the area of the port 903 with respect to the amount of change in the electromagnetic attraction force is reduced, and the variation in the discharge amount of the supply pump P can be suppressed.

  Further, in the region B (corresponding to an intermediate load) in which the spring 110 is moderately bent and the port 903 has a medium opening area, the spring constant continuously changes with respect to the bending, and therefore, the discharge amount change with respect to the electromagnetic attractive force. Becomes continuous (that is, no sudden change in the discharge amount occurs), and the pressure in the common rail 1 can be easily controlled.

  Moreover, even if the shape of the port 903 is a rectangular shape that can be easily processed (see FIG. 3), the characteristics shown in FIG. 11 can be obtained.

In this reference example , a conical coil spring is used as the spring 110 having nonlinear characteristics. However, an unequal pitch coil spring may be used as the spring 110 having nonlinear characteristics as in the modified example shown in FIG. .

DESCRIPTION OF SYMBOLS 1 Common rail 5 Fuel tank 7 High pressure pump 8 Low pressure pump 90 Valve body 92 Valve body 94 1st spring 95 2nd spring 96 Holder (drive means)
98 Stator core (drive means)
99 Armature (drive means)
103 coil (drive means)
104 Yoke (drive means)
903 port

Claims (6)

A common rail (1) for storing high-pressure fuel injected into a cylinder of an internal combustion engine, a high-pressure pump (7) for pumping high-pressure fuel to the common rail (1), and fuel in a fuel tank (5) for the high-pressure pump A metering valve used in a fuel injection system including a low-pressure pump (8) for supplying to (7) and adjusting a flow rate of fuel sent from the low-pressure pump (8) to the high-pressure pump (7);
A valve body (90) having a port (903) through which fuel sent from the low pressure pump (8) to the high pressure pump (7) passes;
A valve body (92) that is slidably inserted into the valve body (90) to change the opening area of the port (903);
Driving means (96, 98, 99, 103, 104) for driving the valve element (92) in the valve opening direction by electromagnetic attraction;
A first spring (94) for urging the valve body (92) in the valve closing direction;
The first spring (94) is interposed between the valve body (92) and arranged in series with the first spring (94), and urges the valve body (92) in the valve closing direction. A spring (95),
In the region where the electromagnetic attractive force is a predetermined value or less, the amount of bending of only the first spring (94) of the two springs (94, 95) changes according to the magnitude of the electromagnetic attractive force,
In the region where the electromagnetic attractive force exceeds the predetermined value, the fuel injection is characterized in that the amount of bending of the two springs (94, 95) varies according to the magnitude of the electromagnetic attractive force. Metering valve for system. An intermediate member (93) sandwiched between the first spring (94) and the second spring (95) and slidably inserted into the valve body (90);
The first spring (94) is sandwiched between the valve body (92) and the intermediate member (93),
When the intermediate member (93) abuts against a movement restricting surface (902) formed on the valve body (90), the movement of the intermediate member (93) in the valve body closing direction is restricted,
In a region where the electromagnetic attractive force is equal to or less than the predetermined value, the state where the intermediate member (93) is in contact with the movement restricting surface (902) is maintained,
2. The fuel injection system adjustment according to claim 1, wherein the intermediate member is separated from the movement restricting surface in a region where the electromagnetic attractive force exceeds the predetermined value. Quantity valve. A common rail (1) for storing high-pressure fuel injected into a cylinder of an internal combustion engine, a high-pressure pump (7) for pumping high-pressure fuel to the common rail (1), and fuel in a fuel tank (5) for the high-pressure pump A metering valve used in a fuel injection system including a low-pressure pump (8) for supplying to (7) and adjusting a flow rate of fuel sent from the low-pressure pump (8) to the high-pressure pump (7);
A valve body (90) having a port (903) through which fuel sent from the low pressure pump (8) to the high pressure pump (7) passes;
A valve body (92) that is slidably inserted into the valve body (90) to change the opening area of the port (903);
Driving means (96, 98, 99, 103, 104) for driving the valve element (92) in the valve opening direction by electromagnetic attraction;
A first spring (94) for urging the valve body (92) in the valve closing direction;
The first spring (94) is interposed between the valve body (92) and arranged in series with the first spring (94), and urges the valve body (92) in the valve closing direction. A spring (95),
The relationship between the spring constant ka of the first spring (94) and the spring constant kb of the second spring (95) is set as ka> kb,
In a region where the electromagnetic attractive force is less than or equal to a predetermined value, the second spring (95) is maintained in an initial load state and the first spring (94) is bent according to the magnitude of the electromagnetic attractive force. The amount changes,
In the region where the electromagnetic attractive force exceeds the predetermined value and is equal to or less than the initial load of the second spring (95), the amount of bending of the two springs (94, 95) does not change,
In a region where the electromagnetic attractive force exceeds the initial load of the second spring (95), the amount of deflection of only the second spring (95) of the two springs (94, 95) according to the magnitude of the electromagnetic attractive force. A metering valve for a fuel injection system, characterized in that is configured to change. An intermediate member (93) sandwiched between the first spring (94) and the second spring (95) and slidably inserted into the valve body (90);
The first spring (94) is sandwiched between the valve body (92) and the intermediate member (93),
When the intermediate member (93) abuts against a movement restricting surface (902) formed on the valve body (90), the movement of the intermediate member (93) in the valve body closing direction is restricted,
In a region where the electromagnetic attractive force is equal to or less than the predetermined value, the state where the intermediate member (93) is in contact with the movement restricting surface (902) is maintained,
In a region where the electromagnetic attractive force exceeds the predetermined value and is equal to or less than the initial load of the second spring (95), the intermediate member (93) is kept in contact with the movement restricting surface (902), and The state in which the valve body (92) and the intermediate member (93) are in contact with each other is maintained,
In the region where the electromagnetic attractive force exceeds the initial load of the second spring (95), the valve body (92) and the intermediate member (93) are kept in contact with each other, and the intermediate member (93) 4. The fuel injection system metering valve according to claim 3, wherein the valve is configured to be separated from the movement regulating surface (902). 5.   5. The method according to claim 1, wherein Pa <Pb, where Pa is an initial load of the first spring (94) and Pb is an initial load of the second spring (95). Metering valve for fuel injection system as described.   The metering valve for a fuel injection system according to any one of claims 1 to 5, wherein the two springs (94, 95) are compression coil springs.

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