Gas fuel injection valve

Abstract

To enhance responsiveness during fuel injection and enable a large flow rate of gas fuel.SOLUTION: A fuel injection valve 10 includes: a first valve 30 having a first movable core 31 disposed to oppose to a fixation core 20 and opening / closing a communication hole 13a through movement of the first movable core 31; and a second valve 40 having a second movable core 41 disposed to oppose to the fixation core 20 and opening / closing an injection hole 14a through movement of the second movable core 41. In the fuel injection valve 10, suction of the first movable core 31 to the fixation core 20 along with generation of a driving magnetic flux moves both of the first valve 30 and the second valve 40 to a valve opening side. After the first valve 30 stops at a first lift position, the second movable core 41 is sucked to the fixation core 20 due to the driving magnetic flux so that the second valve 40 moves to a second lift position where a valve element lift amount is larger than that at the first lift position.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The disclosure herein relates to gas fuel injectors. [Background technology]

[0002] As a gas fuel injection valve used in a direct injection gas engine, for example, a gas metering valve described in Patent Document 1 is known. Patent Document 1 discloses a configuration of a gas metering valve having a valve member that opens the inlet opening of a gas chamber and a shutoff valve provided downstream of the valve member, specifically between the valve member and the outlet opening of the gas chamber, in which the upstream valve member moves to the valve opening side by the magnetic attractive force of an electromagnet, and the downstream shutoff valve moves to the valve opening side by pressure balance after the valve member is opened. Patent Document 1 also discloses a configuration in which when the upstream valve member moves to the valve opening side by the magnetic attractive force of an electromagnet, the downstream shutoff valve moves to the valve opening side mechanically linked to the valve member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2023-513065 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the gas metering valve of Patent Document 1, in a configuration in which the upstream valve member opens due to the magnetic attraction force of an electromagnet and the downstream shutoff valve opens due to pressure balance after the valve member opens, a delay occurs between the opening of the upstream valve member and the opening of the downstream shutoff valve. Therefore, there is a concern that the delay in fuel injection in response to an injection command will be large. Also, in a configuration in which the upstream valve member and the downstream shutoff valve open integrally, the lift amount of the upstream valve member and the lift amount of the downstream shutoff valve are the same. Therefore, it becomes difficult to increase the flow rate of gas fuel.

[0005] The present disclosure has been made in consideration of the above circumstances, and has an object to provide a gas fuel injection valve that can improve responsiveness during fuel injection and achieve a large flow rate of gas fuel. [Means for solving the problem]

[0006] The present disclosure relates to A gas fuel injection valve that injects gas fuel, a main body having a fuel passage through which a gas fuel passes, the main body having an upstream opening provided in a partition portion that partitions the fuel passage into an upstream side and a downstream side, and a downstream opening provided in a most downstream portion of the fuel passage; A fixed core fixed to the main body portion; a first valve having a first movable core disposed opposite to the fixed core, the first valve opening and closing the upstream opening by movement of the first movable core; a second valve having a second movable core disposed opposite to the fixed core, the second valve opening and closing the downstream opening by movement of the second movable core; Equipped with When a driving magnetic flux is generated, the first movable core is attracted to the fixed core, so that both the first valve and the second valve move to the valve opening side, After the first valve stops at the first lift position, the second movable core is attracted to the fixed core by the driving magnetic flux, and the second valve moves to a second lift position having a valve body lift amount greater than that of the first lift position.

[0007] The gas fuel injection valve having the above configuration includes a first valve for opening and closing an upstream opening provided in a partition portion that divides the fuel passage into an upstream side and a downstream side, and a second valve for opening and closing a downstream opening provided in the most downstream portion of the fuel passage. During injection of gas fuel, the first movable core is attracted to the fixed core with the generation of a driving magnetic flux, so that both the first valve and the second valve move to the valve opening side, and after the first valve and the second valve stop at the first lift position, the second movable core is attracted to the fixed core by the driving magnetic flux, so that the second valve moves to a second lift position in which the valve body lift amount is larger than the first lift position.

[0008] Here, the second valve that opens and closes the downstream opening (i.e., the injection hole) moves to the valve opening side together with the first valve due to the attraction of the first movable core to the fixed core at the beginning of the valve opening, and then moves further to the valve opening side by itself due to the attraction of the second movable core to the fixed core. In other words, the second valve opens with high response due to the stepwise magnetic attraction of the first movable core and the second movable core. In addition, the second valve performs a two-stage lift operation, which increases the maximum opening of the downstream opening (injection hole) compared to a single-stage lift configuration, thereby enabling a large flow rate of gas fuel with a large fuel volume. In this case, if the maximum opening of the injection hole is to be increased in the single-stage lift configuration, there is a concern that inconveniences such as the solenoid coil that generates the driving magnetic flux will be forced to be increased, but such inconveniences can be suppressed. As a result, it is possible to improve the response during fuel injection and realize a large flow rate of gas fuel. [Brief description of the drawings]

[0009] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. 4 is an explanatory diagram showing the relationship between a fixed core and each movable core. [Figure 4] 5A and 5B are diagrams for explaining the operation of a fuel injection valve when the fuel injection valve is opened; [Diagram 5] 5A and 5B are diagrams for explaining the operation of a fuel injection valve when the fuel injection valve is opened; [Figure 6] 5A and 5B are diagrams for explaining the operation of the fuel injection valve when the valve is closed. [Figure 7] FIG. 2 is a vertical cross-sectional view showing an example of the configuration of a fuel injection valve. [Figure 8] 4 is a time chart showing changes in the lift amount of a first valve and a second valve and changes in the injection rate when the fuel injection valve is opened and closed; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An embodiment of the gas fuel injection valve according to the present disclosure will be described below with reference to the drawings. The gas fuel injection valve of this embodiment is applied to a direct injection gas engine (internal combustion engine) that uses gas fuel such as hydrogen, CNG (Compressed Natural Gas), and LNG (Liquefied Natural Gas), and the gas fuel is directly injected into the combustion chamber of the gas engine by the gas fuel injection valve. The gas engine is, for example, an engine mounted on a vehicle. In this embodiment, the fuel injection system equipped with the gas fuel injection valve is a so-called low-pressure direct injection system in which gas fuel compressed to about several MPa is injected from the fuel injection valve into the combustion chamber.

[0011] The configuration of the fuel injection valve 10 will be described with reference to Figure 1. Figure 1 shows a longitudinal cross-sectional structure of the main parts of the fuel injection valve 10. In the following description, the direction in which the central axis of the fuel injection valve 10 extends (i.e., the vertical direction in Figure 1) is the axial direction, the direction extending radially from the axis is the radial direction, and the direction extending circumferentially around the axis is the circumferential direction. In Figure 1, the upper side is the base end side (upstream side) of the fuel injection valve 10, and the lower side is the tip side (downstream side).

[0012] The fuel injection valve 10 includes a cylindrical housing 11 having a fuel passage 12 therein. The housing 11 is made of a magnetic material, and a non-magnetic portion 11a made of a non-magnetic material is provided in the axial middle portion. The housing 11 has a cylindrical hollow portion, and the fuel passage 12 is formed by the hollow portion extending in the axial direction. A gas fuel is supplied to the fuel passage 12 from the axial base end side (upper side in the figure). When hydrogen gas is used as the gas fuel, the gas fuel compressed to, for example, about 3 MPa is supplied to the fuel passage 12 from a fuel supply unit on the upstream side.

[0013] The housing 11 has a partition wall 13 that divides the fuel passage 12 into an upstream side and a downstream side, and has an end plate portion 14 at its axial tip. A fuel chamber 15 is formed between the partition wall 13 and the end plate portion 14 inside the housing 11. The fuel injection valve 10 is mounted on the gas engine with the end plate portion 14 exposed inside the engine combustion chamber. The end plate portion 14 does not necessarily have to be flat extending perpendicular to the axial direction as shown in the figure, and may be, for example, conical with a convex tip.

[0014] The partition wall 13 is provided with a communication hole 13a that communicates between the upstream side and the downstream side of the partition wall 13. A plurality of communication holes 13a are provided in the partition wall 13 at positions aligned in the circumferential direction. The opening shape of each communication hole 13a may be any shape, and may be an arc shape extending in the circumferential direction or a circle. In addition, the end plate portion 14 is provided with an injection hole 14a at the most downstream portion of the fuel passage 12, which injects gas fuel into the engine combustion chamber. The injection hole 14a is provided in the center of the end plate portion 14.

[0015] The housing 11 corresponds to the "main body" and the partition wall 13 corresponds to the "partition". The communication hole 13a corresponds to the "upstream opening" and the injection hole 14a corresponds to the "downstream opening".

[0016] In the housing 11, a fixed core 20 is fixed between the partition wall 13 and the end plate portion 14, i.e., in the fuel chamber 15. The fixed core 20 is made of a magnetic material. The fixed core 20 has a communication passage 21 that communicates the upstream side with the downstream side, and in the fuel chamber 15, gas fuel can flow from the upstream side to the downstream side of the fixed core 20 through the communication passage 21. FIG. 2(a) is a cross-sectional view taken along line 2a-2a in FIG. 1. As shown in the figure, the fixed core 20 is provided with a plurality of communication passages 21 that are arc-shaped and aligned in the circumferential direction. However, the opening shape of the communication passage 21 may be arbitrary.

[0017] A first valve 30 for opening and closing the communication hole 13a and a second valve 40 for opening and closing the injection hole 14a are provided in the fuel chamber 15. Each of these valves 30, 40 is capable of reciprocating in the axial direction, and the direction in which the first valve 30 opens the communication hole 13a (the opening direction of the first valve 30) and the direction in which the second valve 40 opens the injection hole 14a (the opening direction of the second valve 40) are the same. The opening directions of each of the valves 30, 40 are both downward in the figure.

[0018] The first valve 30 has a first movable core 31 made of a magnetic material, and a seal member 32 provided on the surface of the first movable core 31 facing the partition wall 13. In the first valve 30, the first movable core 31 is disposed opposite the fixed core 20, and the first movable core 31 is attracted to the fixed core 20 to open the injection hole 14a.

[0019] The first movable core 31 is capable of reciprocating in the axial direction within the fuel chamber 15 along the inner peripheral surface of the housing 11. The first movable core 31 has a plurality of communication passages 33 that communicate in the axial direction. FIG. 2(b) is a cross-sectional view taken along line 2b-2b in FIG. 1. As shown in the figure, the first movable core 31 is provided with a plurality of arc-shaped communication passages 33 that are aligned in the circumferential direction. The communication passages 33 are preferably provided at positions that are continuous with the communication passages 21 of the fixed core 20 in the axial direction.

[0020] The seal member 32 has an annular shape and is attached to the upstream end surface of the first movable core 31 at a position facing the communication hole 13a of the partition wall 13. In this case, the seal member 32 comes into contact with the partition wall 13 to close the communication hole 13a, thereby preventing the passage of fuel from the upstream side to the downstream side of the partition wall 13. In addition, the seal member 32 moves away from the partition wall 13 to open the communication hole 13a, thereby allowing the passage of fuel from the upstream side to the downstream side of the partition wall 13. In the first valve 30, the seal member 32 functions as a valve member. The seal member 32 is made of any one of elastic materials having elasticity, such as rubber, resin, and elastomer. More specifically, fluororubber, EPDM (ethylene propylene diene rubber), and the like are preferably used as the seal material.

[0021] The first movable core 31 is provided so that its upstream end face faces the partition wall 13 and its downstream end face faces the fixed core 20 in the axial direction. The downstream end face of the first movable core 31 and the upstream end face of the fixed core 20 face each other in parallel. A first spring 34 made of a compression coil spring is provided between the first movable core 31 and the fixed core 20. The first spring 34 biases the first movable core 31 toward a side moving away from the fixed core 20, that is, toward a side where the seal member 32 closes the communication hole 13a (valve closing side). The fixed core 20 is formed with a spring accommodating portion 22 in the shape of an annular groove, and the first spring 34 is provided in a state of being accommodated in the spring accommodating portion 22. This maintains a state in which the downstream end face of the first movable core 31 is separated from the upstream end face of the fixed core 20.

[0022] In the first valve 30, the first movable core 31 is biased toward the closing side by the first spring 34, so that the communicating hole 13a of the partition wall 13 is closed by the sealing member 32, and an air gap is formed between the first movable core 31 and the fixed core 20.

[0023] The second valve 40 has a second movable core 41 made of a magnetic material and a valve body 42 that moves integrally with the second movable core 41. In the second valve 40, the second movable core 41 is disposed opposite the fixed core 20, and the injection hole 14a is opened when the second movable core 41 moves toward the fixed core 20. The second valve 40 is an outward opening valve that opens when the valve body 42 moves outside the housing.

[0024] The valve body 42 is needle-shaped and is provided so as to extend in the axial direction from the downstream end face of the second movable core 41. The valve body 42 is provided in a state of being inserted into the insertion hole 26 of the fixed core 20. In comparison between the first valve 30 and the second valve 40, the first valve 30 has a seal member 32 as a valve member provided on the upstream side of the first movable core 31, whereas the second valve 40 has a valve body 42 as a valve member provided on the downstream side of the second movable core 41.

[0025] The second movable core 41 is provided on the upstream side of the fixed core 20 in a state of being incorporated into the recess 35 of the first movable core 31. Thereby, the second movable core 41 can move integrally with the first movable core 31 to the valve opening side (the lower side in the figure). That is, the first movable core 31 has a bottomed cylindrical shape with a hollow portion, and the second movable core 41 is accommodated in the hollow portion in a movable state.

[0026] More specifically, a recess 35 is formed in the center of the cross section of the downstream end surface of the first movable core 31, and the second movable core 41 is accommodated in the recess 35 in a state of being reciprocally movable in the axial direction with respect to the first movable core 31. Both the recess 35 of the first movable core 31 and the second movable core 41 are circular in cross section, and the second movable core 41 is accommodated inside the first movable core 31 which forms an annular shape. In this case, the upstream end surface of the second movable core 41 faces the bottom (axial end surface) of the recess 35. When the first movable core 31 moves to the valve opening side, the first movable core 31 hits the second movable core 41, and these movable cores 31 and 41 move integrally to the valve opening side.

[0027] The first movable core 31 is provided with a through hole 36 that penetrates in the axial direction and communicates with the recess 35. Thereby, when the first movable core 31 moves to the valve opening side and the communication hole 13a of the partition wall 13 is opened, the gas fuel can flow into the back side of the second movable core 41. Here, in the first movable core 31, the through hole 36 is provided by reducing the diameter of the recess 35, and the stepped portion formed by the recess 35 and the through hole 36 serves as a contact portion 37 that contacts the second movable core 41 when the first movable core 31 moves integrally with the second movable core 41.

[0028] A sheet-like non-magnetic body portion 43 made of a non-magnetic material is provided on the upstream end surface of the second movable core 41. The non-magnetic body portion 43 only needs to be provided between the bottom surface of the recess of the first movable core 31 and the second movable core 41, and only needs to be provided on at least one of the bottom surface of the recess of the first movable core 31 and the second movable core 41.

[0029] The valve body 42 has a tip valve portion 44 at its axial tip. The valve body 42 is inserted into the injection hole 14a, and the tip valve portion 44 closes the injection hole 14a from the outside of the housing. In this case, the injection hole 14a is opened by the tip valve portion 44 moving away from the end plate portion 14. The valve body 42 is preferably made of a metal material, a nonmetal material, or other non-elastomer material having excellent heat resistance. The valve body 42 has an outward opening structure, which suppresses the flame and combustion pressure in the engine combustion chamber from flowing into the injection valve.

[0030] A second spring 45 made of a compression coil spring is provided between the second movable core 41 and the fixed core 20. The second spring 45 biases the second movable core 41 toward a side moving away from the fixed core 20, i.e., toward a side where the tip valve portion 44 of the valve body 42 closes the injection hole 14a (valve closing side). The fixed core 20 is formed with a spring accommodating portion 23 at a position surrounding the shaft portion of the valve body 42, and the second spring 45 is provided in a state of being accommodated in the spring accommodating portion 23.

[0031] Furthermore, a recess 24 is formed in the center of the cross section on the upstream end face of the fixed core 20. The recess 24 is provided at a position axially opposing the second movable core 41 and is sized to accommodate the tip end side of the second movable core 41. On the inner circumferential surface of the recess 24 in the fixed core 20, a circular non-magnetic portion 25 made of a non-magnetic material is provided.

[0032] In the second valve 40, the second movable core 41 is biased toward the valve closing side by the second spring 45, so that the injection hole 14a is closed by the tip valve portion 44 of the valve body 42, and an air gap is formed between the second movable core 41 and the bottom surface of the recess 24 of the fixed core 20.

[0033] The first movable core 31 and the second movable core 41 both face the fixed core 20 from the upstream side in the axial direction, but the separation distances (air gap dimensions) of their respective air gaps are different, and the configuration thereof will be supplemented and explained with reference to FIG. 3. FIG. 3 is an explanatory diagram showing the relationship between the fixed core 20 and the movable cores 31, 41. In FIG. 3, the illustration of the communication passages 21, 33 of the fixed core 20 and the first movable core 31 is omitted.

[0034] As shown in FIG. 3, an air gap G1 is formed between the downstream end face of the first movable core 31 and the upstream end face of the fixed core 20, and an air gap G2 is formed between the downstream end face of the second movable core 41 and the upstream end face of the fixed core 20 (specifically, the bottom surface of the recess 24). The separation distance D1 of the air gap G1 and the separation distance D2 of the air gap G2 satisfy D1 < D2. In this case, the first movable core 31 is movable in the axial direction with the separation distance D1 as the upper limit, and the second movable core 41 is movable in the axial direction with the separation distance D2 as the upper limit.

[0035] In FIGS. 1 and 3, the downstream end face of the first movable core 31 and the downstream end face of the second movable core 41 are flush with each other in the initial state (non-operating state), but the configuration is not limited thereto. For example, a configuration in which the downstream end face of the second movable core 41 is recessed into the inner side of the recess with respect to the downstream end face of the first movable core 31, or a configuration in which the downstream end face of the second movable core 41 protrudes outside the recess with respect to the downstream end face of the first movable core 31 may be adopted. In any case, it is sufficient that the separation distances D1, D2 of the air gaps G1, G2 satisfy the relationship D1 < D2.

[0036] A solenoid coil 51 is provided at a position surrounding the first movable core 31 and the fixed core 20 in the fuel injection valve 10. The solenoid coil 51 is provided at a position overlapping the fixed core 20 and the movable cores 31, 41 in the axial direction.

[0037] The fuel injection system of this embodiment includes, in addition to the fuel injection valve 10, a drive circuit 53 that energizes the solenoid coil 51, and a control device 54 that controls the fuel injection of the fuel injection valve 10. In the fuel injection system, the drive circuit 53 is connected to the solenoid coil 51 via a harness 52. The energization by the drive circuit 53 is controlled by the control device 54. The control device 54 is made up of a microcomputer having a CPU and various memories, and outputs an energization signal to the drive circuit 53 in accordance with the combustion cycle of each cylinder during engine operation, causing the fuel injection valve 10 to inject fuel.

[0038] In the fuel injection valve 10, the solenoid coil 51 is energized by the drive circuit 53 to generate magnetic energy, which attracts the first movable core 31 and the second movable core 41 to the fixed core 20. As a result, the first valve 30 and the second valve 40 are opened, and gas fuel is injected from the injection hole 14a. In this embodiment, one solenoid coil 51 is configured to simultaneously drive the two valves 30, 40 to open.

[0039] Next, a detailed description will be given of the operation of the fuel injection valve 10 when it is opened and closed. Figures 4(a) to (c) and Figures 5(a) to (c) are diagrams for explaining the operation of the fuel injection valve 10 when it is opened, and Figures 6(a) to (c) are diagrams for explaining the operation of the fuel injection valve 10 when it is closed.

[0040] First, the operation of the fuel injection valve 10 when it is opened will be described with reference to Figures 4(a) to (c). In Figure 4(a), current begins to be passed through the solenoid coil 51. This generates a driving magnetic flux, forms a magnetic circuit by a first magnetic flux path indicated by an arrow C1 in the figure, and generates a magnetic attraction force between the first movable core 31 and the fixed core 20, which attracts them to each other.

[0041] As shown in Fig. 4(b), the first movable core 31 is attracted to the fixed core 20, so that the second movable core 41 moves together with the first movable core 31, and both the first valve 30 and the second valve 40 are opened. At this time, the first movable core 31 and the second movable core 41 have different separation distances D1, D2 from the fixed core 20 in the initial state (see Fig. 3), and when the solenoid coil 51 starts to be energized, a magnetic circuit is formed through a path that passes through the first movable core 31, which is closer to the first movable core 31 of the two movable cores 31, 41. As a result, when the energization starts, the magnetic flux flows intensively through the first magnetic flux path C1 including the first movable core 31, so that the opening response of the first valve 30 is improved.

[0042] In the fuel injection valve 10, the first movable core 31 is disposed inside the solenoid coil 51, and the second movable core 41 is disposed further inside the first movable core 31. That is, the first movable core 31 is disposed radially outside the second movable core 41, that is, closer to the solenoid coil 51 than the second movable core 41. Therefore, when the solenoid coil 51 starts to be energized, a stronger magnetic attraction force is generated in the first movable core 31 against the fixed core 20 than in the second movable core 41, and the opening response of the first valve 30 is improved.

[0043] Further, a non-magnetic part 43 is interposed between the opposing surfaces of the first movable core 31 and the second movable core 41 that face each other in the axial direction. The non-magnetic part 43 functions as a magnetic flux regulating part that regulates the passage of magnetic flux between the first movable core 31 and the second movable core 41 in the state shown in Figures 4(a) and (b). This prevents magnetic flux from passing through unintended paths, and causes magnetic flux to flow intensively through the first magnetic flux path C1.

[0044] In the state of Fig. 4(b), the first movable core 31 abuts (seats) on the fixed core 20, and the distance between the second movable core 41 and the fixed core 20 is narrower than that in Fig. 4(a). The second movable core 41 moves to the valve opening side together with the first movable core 31 until the first movable core 31 abuts on the fixed core 20, and moves to the valve opening side by itself due to inertia after the first movable core 31 abuts on the fixed core 20. Therefore, the distance between the second movable core 41 and the fixed core 20 is narrowed, and a magnetic circuit is formed by the second magnetic flux path indicated by the arrow C2 in addition to the first magnetic flux path indicated by the arrow C1, and a magnetic attraction force is generated that attracts the second movable core 41 and the fixed core 20 to each other.

[0045] As a result, as shown in Fig. 4(c), the second movable core 41 is attracted to the fixed core 20 and seats on the fixed core 20. In this state, both the first movable core 31 and the second movable core 41 are seated on the fixed core 20, and the opening degree of the injection hole 14a by the valve body 42 of the second valve 40 becomes maximum. The state of Fig. 4(c) is maintained by continuing the energization of the solenoid coil 51.

[0046] Here, the fixed core 20 is formed with a spring accommodating portion 22 in the shape of an annular groove, and the first spring 34 is accommodated in the spring accommodating portion 22. Therefore, the portion of the fixed core 20 facing the first movable core 31 is thinned in the radial direction, forming a magnetically restricted portion. In this case, magnetic saturation occurs in the magnetically restricted portion of the fixed core 20 (i.e., the first magnetic flux path C1 passing through the first movable core 31 and the fixed core 20), and the amount of magnetic flux in the second magnetic flux path C2 (detour path) passing through the second movable core 41 and the fixed core 20 increases. This allows the second movable core 41 to be attracted to the fixed core 20 appropriately.

[0047] 4(c), a non-magnetic part 25 is interposed between the fixed core 20 and the second movable core 41 which face each other in the radial direction. The non-magnetic part 25 functions as a magnetic flux restricting part which restricts magnetic flux from passing in the radial direction between the fixed core 20 and the second movable core 41. This allows the fixed core 20 and the second movable core 41 to appropriately generate a magnetic attraction force in the axial direction.

[0048] In FIGS. 4(a) to 4(c), in FIG. 4(a), the first valve 30 and the second valve 40 are in the closed valve positions. In FIG. 4(b), the first valve 30 and the second valve 40 move to the first lift position. That is, the second valve 40 moves to the first lift position within the movement range of the first valve 30 together with the first valve 30. Thereafter, as shown in FIG. 4(c), the second valve 40 moves alone to the second lift position where the valve body lift amount is larger than that of the first lift position.

[0049] As shown in FIG. 4(a), the movement amount of the first movable core 31 when the first movable core 31 is attracted to the fixed core 20 with the generation of the driving magnetic flux is A1. As shown in FIG. 4(b), after the movement of the first movable core 31, the movement amount of the second movable core when the second movable core 41 is attracted to the fixed core 20 alone is A2. And the movement amounts A1 and A2 are in the relationship of A1 < A2. In this case, since the movement amount A1 of the first movable core 31 at the beginning of energization is relatively small, the valve opening responsiveness of the first valve 30 at the beginning of energization is enhanced. Also, since the single movement amount A2 of the second movable core is relatively large, the maximum opening degree of the second valve 40 can be increased while taking into account that an inertial force is applied to the second movable core 41 by the movement of the first movable core 31.

[0050] Next, the flow of the gaseous fuel in the fuel injection valve 10 will be described with reference to FIGS. 5(a) to 5(c). Note that each state shown in FIGS. 5(a) to 5(c) is the same as each state shown in FIGS. 4(a) to 4(c), respectively.

[0051] In FIG. 5(a), the first movable core 31 and the second movable core 41 move to the valve-opening side as the solenoid coil 51 starts to be energized, and in FIG. 5(b), both the first valve 30 and the second valve 40 are in the valve-opening state. At this time, as the first valve 30 opens, gas fuel flows into the fuel chamber 15 from the communication hole 13a. In addition, the injection hole 14a is opened, and fuel injection from the injection hole 14a is started. In the fuel chamber 15, the gas fuel flowing in from the communication hole 13a flows to the downstream side of the fixed core 20 through the respective communication passages 33, 21 of the first movable core 31 and the fixed core 20, and also flows into the back side of the second movable core 41 through the through hole 36 of the first movable core 31. At this time, the second movable core 41 is pushed to the valve-opening side by the gas fuel flowing into the back side of the second movable core 41, and the movement of the second movable core 41 to the valve-opening side is assisted.

[0052] 5(c), the second valve 40 is at the maximum opening degree, and the maximum opening state is maintained by energization of the solenoid coil 51. In this state, the second movable core 41 moves relative to the first movable core 31, so that a back space is formed on the back side of the second movable core 41 in the recess 35 of the first movable core 31, and gas fuel is introduced into the back space.

[0053] Next, the operation of the fuel injection valve 10 when the valve is closed will be described with reference to Figures 6(a) to 6(c). In Figure 6(a), the first movable core 31 and the second movable core 41 are attracted to the fixed core 20 by the driving magnetic flux, i.e., both the first valve 30 and the second valve 40 are in a valve-closed state, and in this state, the driving magnetic flux is extinguished by stopping the energization of the solenoid coil 51. As a result, the magnetic attraction force between each of the movable cores 31, 41 and the fixed core 20 disappears, and the first movable core 31 and the second movable core 41 start to move to the valve-closing side due to the biasing force of the first spring 34 and the second spring 45.

[0054] In this embodiment, when the fuel injection valve 10 closes, due to the disappearance of the driving magnetic flux, the first valve 30 among the first valve 30 and the second valve 40 returns to the closed position first, and after the first valve 30 returns to the closed position, the second valve 40 is returned to the closed position. Therefore, after the disappearance of the driving magnetic flux (after the energization of the solenoid coil 51 is stopped), as shown in FIG. 6(b), a state occurs temporarily where the first valve 30 is closed and the second valve 40 is not closed, and in this state, the gaseous fuel in the fuel chamber 15 flows out from the injection hole 14a. In this case, by closing the communication hole 13a, which is the upstream opening, earlier than the injection hole 14a, which is the downstream opening, the supply of gaseous fuel from the upstream side is quickly stopped after the energization of the solenoid coil 51 is stopped, and due to the outflow of the gaseous fuel from the injection hole 14a, the pressure in the fuel chamber 15 quickly decreases.

[0055] In FIG. 6(b), when the first valve 30 shifts from the open state to the closed state, the space on the back side of the second movable core 41 becomes a closed space (the dotted part in the figure). Therefore, after the first valve 30 closes, the movement of the second movable core 41 (the second valve 40) toward the closed side is hindered by the gaseous fuel remaining in the closed space on the back side of the second movable core 41. As a result, after the disappearance of the driving magnetic flux, the closing operation of the second valve 40 is delayed, and the outflow of the gaseous fuel from the fuel chamber 15 through the injection hole 14a occurs quickly. The gaseous fuel in the closed space is gradually released through the gap between the first movable core 31 and the second movable core 41, etc.

[0056] As shown in FIG. 7, in a state where the first movable core 31 and the second movable core 41 are attracted to the fixed core 20 by the driving magnetic flux (corresponding to the state in FIG. 6(a)), it is preferable that the separation distance between the first movable core 31 and the fixed core 20 is larger than the separation distance between the second movable core 41 and the fixed core 20. Specifically, a plate-shaped spacer 61 made of a non-magnetic material is interposed between the opposing surfaces of the first movable core 31 and the fixed core 20. A solid gap is formed between the first movable core 31 and the fixed core 20 by this spacer 61. In this case, when the first valve 30 and the second valve 40 move to the valve closing side as the driving magnetic flux disappears, the first movable core 31 is more likely to move away from the fixed core 20 than the second movable core 41.

[0057] Thereafter, in FIG. 6(c), the second movable core 41 returns to the valve closing position by the biasing force of the second spring 45, and the second valve 40 is in the valve closing state. Thereby, the fuel injection is stopped. At this time, the pressure in the fuel chamber 15 acts as a biasing force on the valve opening side of the second valve 40, and the biasing force of the second spring 45 and the pressure in the engine combustion chamber (in-cylinder pressure) act as biasing forces on the valve closing side. When the pressure in the fuel chamber 15 decreases and falls below the valve closing force by the biasing force of the second spring 45 and the in-cylinder pressure, the valve body 42 closes the valve.

[0058] FIG. 8 is a time chart showing the changes in the lift amounts of the first valve 30 and the second valve 40 and the change in the injection rate when the fuel injection valve 10 opens and closes. The energization signal is an injection valve control signal as an energization command output from the control device 54. When the energization signal is turned on, the solenoid coil 51 is energized, and when the energization signal is turned off, the energization of the solenoid coil 51 is stopped. The injection rate is the fuel injection amount per unit time. In FIG. 8, as the lift amounts of the respective valves 30, 40, the lift amount of the first valve 30 is indicated by a one-dot chain line, and the lift amount of the second valve 40 is indicated by a solid line.

[0059] 8, at timing t1, the energization signal is turned on to start energizing the solenoid coil 51, which starts lifting the first valve 30 and the second valve 40. At the beginning of energization, the first valve 30 and the second valve 40 move together, so the lift amounts of these valves 30, 40 are the same. As the lift amounts of the valves 30, 40 increase, the injection rate gradually increases.

[0060] After that, at timing t2, the first movable core 31 hits the fixed core 20, and the first valve 30 stops at the first lift position. After timing t2, the second valve 40 lifts independently, and only the lift amount of the second valve 40 increases.

[0061] At timing t3, the second movable core 41 hits the fixed core 20, and the second valve 40 stops at the second lift position. In this case, the second valve 40 performs a two-stage lift operation, which makes it possible to increase the maximum opening degree of the injection hole 14a and increase the injection rate.

[0062] After that, at timing t4, the energization signal is turned off to stop energization of the solenoid coil 51. At this time, the first valve 30 returns to the closed position immediately after the disappearance of the driving magnetic flux, whereas the second valve 40 returns to the closed position with a delay after the disappearance of the driving magnetic flux. In other words, the first valve 30 returns to the closed position first due to the biasing force of the first spring 34, and the second valve 40 returns to the closed position due to the biasing force of the second spring 45 after the first valve 30 returns to the closed position.

[0063] In this case, the communication hole 13a, which is the upstream opening, is closed first, so that the fuel supply from the upstream side is stopped immediately after the solenoid coil 51 is de-energized, and the pressure in the fuel chamber 15 is quickly reduced. This allows the injection rate to be reduced more quickly after the energization signal is turned off, resulting in a good injection cutoff.

[0064] According to the present embodiment described above in detail, the following excellent effects can be obtained.

[0065] In the fuel injection valve 10, the second valve 40 that opens and closes the injection hole 14a moves together with the first valve 30 toward the valve opening side when the first movable core 31 is attracted to the fixed core 20, and then moves further toward the valve opening side by itself due to the attraction of the second movable core to the fixed core. That is, the second valve 40 opens with high response as the first movable core 31 and the second movable core 41 are magnetically attracted in stages. In addition, the second valve 40 performs a two-stage lift operation, which increases the maximum opening of the injection hole 14a compared to a single-stage lift configuration, thereby enabling a large flow rate of gas fuel with a large fuel volume. In this case, if the maximum opening of the injection hole 14a is increased in the single-stage lift configuration, there is a concern that inconveniences such as the solenoid coil 51 that generates the driving magnetic flux must be increased in size, but such inconveniences can be suppressed. As a result, the responsiveness during fuel injection can be improved and a large flow rate of gas fuel can be achieved.

[0066] After the generation of the driving magnetic flux, magnetic saturation is caused in the first magnetic flux path C1 passing through the first movable core 31 and the fixed core 20, and this magnetic saturation increases the amount of magnetic flux in the second magnetic flux path C2 passing through the second movable core 41 and the fixed core 20. As a result, when the solenoid coil 51 first starts to be energized, the first movable core 31 is attracted, i.e., the first valve 30 is opened with good responsiveness, and subsequently, the second movable core 41 is attracted, i.e., the lift amount of the second valve 40 is appropriately increased.

[0067] The second movable core 41 is movably housed in the hollow portion of the first movable core 31, and a solenoid coil 51 is provided to surround the first movable core 31 and the fixed core 20. In this case, the first movable core 31 is arranged inside the solenoid coil 51, and the second movable core 41 is arranged further inside that. This allows the first movable core 31 to generate a stronger magnetic attraction force to the fixed core 20 than the second movable core 41 when the solenoid coil 51 first starts to be energized, thereby improving the valve opening responsiveness of the first valve 30.

[0068] The amount of movement of the first movable core 31 when the first movable core 31 is attracted to the fixed core 20 due to the generation of driving magnetic flux is set smaller than the amount of movement of the second movable core 41 when the second movable core 41 is attracted independently to the fixed core 20 after the movement of the first movable core 31. In this case, when the solenoid coil 51 first starts to be energized, the valve opening responsiveness of the first valve 30 is improved, and when the second valve 40 is subsequently opened, an appropriate valve opening operation can be performed by using the inertial force applied by the valve opening operation of the first valve 30.

[0069] When the fuel injection valve 10 is closed from an open state (i.e., a state in which the first movable core 31 and the second movable core 41 are attracted to the fixed core 20 by the driving magnetic flux), the first valve 30 closes the communication hole 13a of the partition wall 13 first, and then the second valve 40 closes the injection hole 14a. In this case, of the communication hole 13a which is an upstream opening and the injection hole 14a which is a downstream opening, the communication hole 13a is closed first, so that the fuel supply from the upstream side is stopped quickly after the energization of the solenoid coil 51 is stopped, and the pressure drop in the fuel chamber 15 is accelerated. This improves the injection cut-off when the energization of the fuel injection valve 10 is stopped.

[0070] In the fuel injection valve 10, when the first valve 30 is in an open state, the gas fuel flows into the back space of the second movable core 41 facing the opposite side to the valve body 42. As a result, the second movable core 41 (second valve 40) is pushed toward the valve opening side by the gas fuel flowing into the back space. Therefore, the movement of the second movable core 41 toward the valve opening side can be assisted when the second valve 40 is initially opened. In addition, when the first valve 30 transitions from an open state to a closed state, the back space becomes a closed space closed by the first valve 30. As a result, after the first valve 30 is closed, the gas fuel remaining in the closed space (back space) prevents the second movable core 41 (second valve 40) from returning to the valve closing side. Therefore, after the solenoid coil 51 is de-energized, the gas fuel can be quickly discharged from the fuel chamber 15 through the injection hole 14a, which can improve the injection cut-off at the end of injection.

[0071] In the valve opening state of the fuel injection valve 10, the separation distance between the first movable core 31 and the fixed core 20 is made larger than the separation distance between the second movable core 41 and the fixed core 20 (see FIG. 7). In this case, when the first valve 30 and the second valve 40 move toward the valve closing side as the driving magnetic flux disappears, the first movable core 31 is more likely to move away from the fixed core 20 than the second movable core 41. Therefore, a configuration in which the communication hole 13a is closed first among the communication hole 13a and the injection hole 14a can be preferably realized.

[0072] (Other embodiments) The above embodiment may be modified as follows, for example.

[0073] · In the above embodiment, the movement amount A1 of the first movable core 31 when the first movable core 31 is attracted to the fixed core 20 as the driving magnetic flux is generated, and the movement amount A2 of the second movable core when the second movable core 41 is attracted to the fixed core 20 alone after the movement of the first movable core 31 are in the relationship of A1 < A2, but this may be changed. The movement amounts A1 and A2 may be set to A1 = A2 or A1 > A2.

[0074] · In the above embodiment, the first movable core 31 has a bottomed cylindrical shape with a hollow portion, and the annular portion and the contact portion 37 are made of a magnetic material. However, this may be changed, and a contact plate made of a non-magnetic material may be provided as a contact portion at the axial end of the annular portion of the first movable core 31.

[0075] The technical idea extracted from the above embodiment is described below. [Configuration 1] A gas fuel injection valve (10) for injecting gas fuel, having a fuel passage (12) through which gas fuel passes, and having an upstream opening (13a) provided in a partitioning portion (13) that partitions the fuel passage into an upstream side and a downstream side, and a downstream opening (14a) provided at the most downstream portion of the fuel passage, and a main body portion (11), a fixed core (20) fixed to the main body portion, a first valve (30) having a first movable core (31) disposed opposite to the fixed core, the first valve (30) opening and closing the upstream opening by movement of the first movable core; a second valve (40) having a second movable core (41) disposed opposite to the fixed core and configured to open and close the downstream opening by movement of the second movable core; Equipped with When a driving magnetic flux is generated, the first movable core is attracted to the fixed core, so that both the first valve and the second valve move to the valve opening side, A gas fuel injection valve, wherein after the first valve stops at a first lift position, the second movable core is attracted to the fixed core by the driving magnetic flux, thereby moving the second valve to a second lift position having a valve body lift amount greater than the first lift position. [Configuration 2] The gas fuel injection valve according to configuration 1, wherein after the driving magnetic flux is generated, magnetic saturation is caused in a first magnetic flux path passing through the first movable core and the fixed core, and the magnetic saturation increases an amount of magnetic flux in a second magnetic flux path passing through the second movable core and the fixed core. [Configuration 3] The first movable core is cylindrical and has a hollow portion, and the second movable core is movably accommodated in the hollow portion. 3. The gas fuel injection valve according to configuration 1 or 2, wherein a solenoid coil (51) generating the driving magnetic flux is provided so as to surround the first movable core and the fixed core. [Configuration 4] The gas fuel injection valve according to any one of configurations 1 to 3, wherein a movement amount of the first movable core when the first movable core is attracted to the fixed core due to generation of the driving magnetic flux is smaller than a movement amount of the second movable core when the second movable core is attracted to the fixed core after the movement of the first movable core. [Configuration 5] a first spring (34) that biases the first valve to a valve closing side; a second spring (45) that biases the second valve to a valve closing side, 5. The gas fuel injection valve according to any one of configurations 1 to 4, wherein, when the driving magnetic flux is eliminated from a state in which the first movable core and the second movable core are attracted to the fixed core by the driving magnetic flux, the first valve of the first valve and the second valve is returned to the closed position first by the biasing force of the first spring, and after the first valve returns to the closed position, the second valve is returned to the closed position by the biasing force of the second spring. [Configuration 6] The first movable core is cylindrical and has a hollow portion, and the second movable core is movably accommodated in the hollow portion. the second valve is an outside-opening valve that is opened when a valve body (42) integrally provided with the second movable core moves outward from the main body portion, 6. The gas fuel injection valve according to configuration 5, wherein, when the first valve is in an open state, gas fuel flows into a back space that communicates with the hollow portion and faces the side of the second movable core opposite the valve body, while when the first valve transitions from an open state to a closed state, the back space becomes a closed space closed by the first valve. [Configuration 7] The gas fuel injection valve according to configuration 5 or 6, wherein when the first movable core and the second movable core are attracted to the fixed core by the driving magnetic flux, a distance between the first movable core and the fixed core is greater than a distance between the second movable core and the fixed core. [Explanation of symbols]

[0076] 10... fuel injection valve, 11... housing, 12... fuel passage, 13... partition wall, 13a... communication hole, 14a... injection hole, 20... fixed core, 30... first valve, 31... first movable core, 40... second valve, 41... second movable core.

Claims

1. A gas fuel injection valve (10) for injecting gas fuel, a main body portion (11) having a fuel passage (12) through which a gas fuel passes, the main body portion having an upstream opening (13a) provided in a partition portion (13) that partitions the fuel passage into an upstream side and a downstream side, and a downstream opening (14a) provided at a most downstream portion of the fuel passage; A fixed core (20) fixed to the main body portion; a first valve (30) having a first movable core (31) disposed opposite to the fixed core, the first valve opening and closing the upstream opening by movement of the first movable core; a second valve (40) having a second movable core (41) disposed opposite to the fixed core and configured to open and close the downstream opening by movement of the second movable core; Equipped with When a driving magnetic flux is generated, the first movable core is attracted to the fixed core, so that both the first valve and the second valve move to the valve opening side, A gas fuel injection valve, wherein after the first valve stops at a first lift position, the second movable core is attracted to the fixed core by the driving magnetic flux, thereby moving the second valve to a second lift position having a valve body lift amount greater than the first lift position.

2. 2. The gas fuel injection valve as described in claim 1, wherein after the driving magnetic flux is generated, magnetic saturation is caused in a first magnetic flux path passing through the first movable core and the fixed core, and the magnetic saturation increases an amount of magnetic flux in a second magnetic flux path passing through the second movable core and the fixed core.

3. The first movable core is cylindrical and has a hollow portion, and the second movable core is movably accommodated in the hollow portion.

2. The gas fuel injection valve according to claim 1, further comprising a solenoid coil (51) surrounding the first movable core and the fixed core to generate the driving magnetic flux.

4. 2. The gas fuel injection valve according to claim 1, wherein a movement amount of the first movable core when the first movable core is attracted to the fixed core due to generation of the driving magnetic flux is smaller than a movement amount of the second movable core when the second movable core is attracted to the fixed core after movement of the first movable core.

5. A first spring (34) that biases the first valve toward a valve closing side; A second spring (45) that biases the second valve to a valve closing side, 5. The gas fuel injection valve according to claim 1, wherein when the driving magnetic flux is eliminated from a state in which the first movable core and the second movable core are attracted to the fixed core by the driving magnetic flux, the first valve of the first valve and the second valve is returned to the closed position first by the biasing force of the first spring, and after the first valve returns to the closed position, the second valve is returned to the closed position by the biasing force of the second spring.

6. The first movable core is cylindrical and has a hollow portion, and the second movable core is movably accommodated in the hollow portion. the second valve is an outer opening valve that is opened when a valve body (42) integrally provided with the second movable core moves to the outside of the main body portion, 6. The gas fuel injection valve according to claim 5, wherein, when the first valve is in an open state, gas fuel flows into a back space that communicates with the hollow portion and faces the side of the second movable core opposite the valve body, while when the first valve transitions from an open state to a closed state, the back space becomes a closed space closed by the first valve.

7. 6. The gas fuel injection valve according to claim 5, wherein when the first movable core and the second movable core are attracted to the fixed core by the driving magnetic flux, a distance between the first movable core and the fixed core is greater than a distance between the second movable core and the fixed core.

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