FUEL SUPPLY DEVICE

Abstract

Fuel supply device for a four-stroke internal combustion engine using hydrogen as fuel and having a plurality of cylinders, comprising: an intake port with a branching section branching from an upstream side towards a downstream side to correspond to the number of cylinders, a single-pipe section on an upstream side of the branching section, and intake port sections on a downstream side of the branching section; and a plurality of first fuel injectors provided in each of the intake port sections, wherein a maximum injection duration of the first fuel injector is a value corresponding to a valve opening duration of an intake valve of the internal combustion engine; a second fuel injector is provided in the single-pipe section or the branching section;and the minimum injection quantity of the second fuel injector is smaller than the minimum injection quantity of the first fuel injector.

Description

Background of the inventionTechnical field

[0001] The present disclosure relates to a fuel supply device.

[0002] This application claims priority to Japanese patent application JP 2023-123264 A, filed on July 28, 2023, the entire contents of which are incorporated herein by reference. State of the art

[0003] Conventionally, a port injection type internal combustion engine is known in which a fuel injection valve is provided in an intake port and fuel is injected into the intake port (see, for example, Japanese Unexamined Patent Publication JP 2011-058435 A).

[0004] Recently, an internal combustion engine that uses hydrogen as fuel was investigated. Considering the amount of heat per volume of hydrogen, it is necessary to increase the injected gas volume compared to other gaseous fuels, for example, to generate the same amount of heat. However, in general, when the maximum flow rate of a fuel injector is increased, the minimum injection quantity, which corresponds to the minimum injection time (period) of the fuel injector, also tends to increase with the maximum flow rate. Therefore, for example, when the fuel flow rate is low, such as during idling, the minimum injection quantity of the fuel injector may be too large to adequately deliver the fuel.

[0005] The present disclosure provides a fuel supply device capable of adequately supplying fuel even when the fuel flow rate to be injected through a fuel injection valve is low in such an internal combustion engine using hydrogen as fuel. Summary of the invention

[0006] A fuel supply device according to one aspect of the present disclosure is a fuel supply device for a four-stroke internal combustion engine that uses hydrogen as fuel and has a plurality of cylinders, the fuel supply device comprising: an intake passage having a branch portion branching from an upstream side toward a downstream side so as to correspond to the number of cylinders; a single pipe portion on an upstream side of the branch portion and intake port portions on a downstream side of the branch portion; and a plurality of first fuel injection valves provided in each of the intake port portions. A maximum injection period of the first fuel injection valve is a valve opening period.A value corresponding to the valve opening period of an intake valve of the internal combustion engine; a second fuel injection valve is provided in the single pipe section or the branch section; and a minimum injection amount of the second fuel injection valve is smaller than a minimum injection amount of the first fuel injection valve. Short description of the characters Fig. 1 is a schematic configuration diagram of an internal combustion engine having a fuel supply device according to an embodiment. Fig. 2 is a diagram illustrating the injection time (period) of a fuel injector. Fig. 3 is a flowchart showing a processing example of fuel injection by the electronic control unit (ECU) of Fig. 1 illustrates. Fig. 4 is a flowchart showing an example of the injection quantity fluctuation learning processing of the electronic control unit (ECU) in Fig. 1 illustrates. Fig. 5 is a schematic configuration diagram of an internal combustion engine having a fuel supply device according to a first modification. Fig. 6 is a schematic configuration diagram of an internal combustion engine having a fuel supply device according to a second modification. Detailed description of the embodiments

[0007] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and a repeated description is omitted.

[0008] Fig. 1 is a schematic configuration diagram of an internal combustion engine with a fuel supply device according to an embodiment. As shown in Fig. As illustrated in Figure 1, a fuel supply device 100 is a device that controls the supply of fuel to an internal combustion engine 1. The fuel supply device 100 is installed, for example, in a vehicle or the like.

[0009] The internal combustion engine 1 is configured as a hydrogen engine that uses hydrogen gas (hereinafter referred to simply as "hydrogen") as fuel. The internal combustion engine 1 is configured, for example, as a four-stroke port-injection reciprocating piston engine.

[0010] The internal combustion engine 1 has a plurality of cylinders 2 (for example, four cylinders). In each of the cylinders 2, a combustion chamber 4 is defined by a cylinder head 3 with an intake valve 3a (or intake valve 3a) and an exhaust valve 3b (or exhaust valve 3b), and a piston. The internal combustion engine 1 draws in air and hydrogen through the intake valve 3a. The internal combustion engine 1 burns hydrogen in the combustion chamber 4 and expels the exhaust gas generated by the combustion through the exhaust valve 3b.

[0011] In the internal combustion engine 1, an intake passage 5 (or intake port 5) and an exhaust passage 6 are connected to communicate with the combustion chamber 4. For example, the intake passage 5 includes an intake manifold (branching portion) 50 branching from the upstream side to the downstream side to correspond to the number of cylinders, a single-pipe portion 5a on the upstream side of the intake manifold 50, and an intake port portion 5b on the downstream side of the intake manifold 50. The single-pipe portion 5a is provided with a throttle valve 5c that adjusts the flow rate of the intake air. The single-pipe portion 5a refers to the intake passage 5 from the intake air inlet portion including the air cleaner to the upstream end of an inlet portion 51 of the intake manifold 50.

[0012] The intake manifold 50 here corresponds to four cylinders 2. The intake manifold 50 is a 1-2-4 type manifold that branches from a (single) inlet portion 51 into four intake port portions 5b. That is, the intake manifold 50 has a first branch portion 50a that branches from the inlet portion 51, which is a (single) intake port, into two intake ports 52, and a pair of second branch portions 50b that further branch from the two intake ports 52 on the downstream side of the first branch portion 50a to each two intake ports 53 (four intake ports in total). Each of the intake ports 53 extends a predetermined length. In each of the intake ports 53, the side of the cylinder head 3 corresponds to the intake port portion 5b.

[0013] The intake manifold 50 has a guide portion 54. The guide portion 54 is provided, for example, at a location branching from an inlet portion 51 to the two intake ports 52. The guide portion 54 enables fluid communication between the inlet portion 51, which is an upstream intake port on the upstream side, and the intake ports 52, which are two or more downstream intake ports on the downstream side. The guide portion 54 guides the intake air to distribute the intake air flowing through the inlet portion 51 to each of the intake ports 52.

[0014] The guide portion 54 may, for example, be a protrusion that protrudes in a mountain shape from a boundary region of the two intake ports 52 toward the interior of the inlet portion 51. When the intake manifold 50 is cast, the protrusion of the guide portion 54 may be formed by using a mold with a boundary portion between the two intake ports 52 that has a shape corresponding to the protrusion. When the intake manifold 50 is made of sheet metal, the protrusion of the guide portion 54 may be formed by using a sheet metal element at a boundary portion between the two intake ports 52 that has a shape corresponding to the protrusion.

[0015] The internal combustion engine 1 has a plurality of first fuel injection valves 7 provided in each of the intake port portions 5b, respectively. For example, each of the four first fuel injection valves 7 is mounted on a rail 8 whose lower end side is bridged across the four intake port portions 5b. Each of the first fuel injection valves 7 is fixed such that the tip side is pressed against a mounting hole provided in the intake port portion 5b. The first fuel injection valve 7 is a primary fuel injection valve (injector) in the internal combustion engine 1 that uses hydrogen as a fuel. Hydrogen is supplied from a fuel tank to the first fuel injection valve 7 via the rail 8. The first fuel injection valve 7 injects hydrogen into the intake port portion 5b.

[0016] The first fuel injector 7 has a maximum injection quantity corresponding to a fuel flow rate (maximum flow rate) required for full-load operation of the internal combustion engine 1. The maximum injection quantity of the first fuel injector 7 corresponds to the hydrogen flow rate during the maximum injection time (period) of the first fuel injector 7. In a four-stroke internal combustion engine using hydrogen as fuel, considering the amount of heat per volume of hydrogen, it is necessary to increase the injected gas volume compared to other gaseous fuels [for example, LPG (or liquid petroleum gas) or the like] in order to generate the same amount of heat, for example. Therefore, the first fuel injector 7 is configured as a so-called high-flow rate injector.For example, a high-flow injector means an injector in which an injection hole diameter is increased to increase the flow rate.

[0017] Fig. Figure 2 is a graph illustrating the injection time (period) of a fuel injector. The horizontal axis in Fig. 2 represents the crank angle of the internal combustion engine 1. The vertical axis in Fig. 2 represents the valve opening degree of the intake valve 3a or the exhaust valve 3b. As in Fig. As illustrated in Fig. 2, in the four-stroke internal combustion engine, there may be an overlap period during which both the intake valve 3a and the exhaust valve 3b are open. Here, in the port injection type internal combustion engine 1 using hydrogen as fuel, hydrogen is supplied during a period in which the intake valve 3a is open. However, in order to prevent backfiring to the intake port 5, there is a tendency to avoid injecting hydrogen during the overlap period in which not only the intake valve 3a but also the exhaust valve 3b is open. Therefore, the maximum injection period of the first fuel injection valve 7 is a period that falls within the period in which only the intake valve 3a is open.That is, in the fuel supply device 100, the maximum injection time (period) of the first fuel injection valve 7 is a value corresponding to the valve opening time (period) of the intake valve 3a of the internal combustion engine 1.

[0018] When there is the overlap time, the maximum injection time of the first fuel injection valve 7 is a time divided into an intake valve non-overlap opening time, which is a time during which the intake valve 3a is open after the exhaust valve 3b is closed (see Fig. 2). When there is no overlap time, the maximum injection time of the first fuel injection valve 7 is a time that falls within the entire time that the intake valve 3a is open. The "time that the intake valve 3a is open" means a time that the valve opening degree of the intake valve 3a is greater than 0. The "time that the intake valve 3a is open" may mean a time that the valve opening degree of the intake valve 3a is significantly greater than 0, for example, such that the valve opening degree is equal to or greater than a predetermined valve opening determination value.

[0019] Second, the minimum injection quantity is described, which corresponds to the minimum injection time (period) of the first fuel injection valve 7. Generally, for example, in the injector, if the injection time (period) is too short, there is a possibility that the needle lift amount in the injector is insufficient and the flow rate per injection is not stabilized. Therefore, the minimum injection quantity is stabilized by setting the minimum injection time (period) in advance through the design as a hardware limitation of the injector. Here, for example, if the injection hole diameter is increased to increase the maximum injection quantity, the injection quantity in the minimum injection time (period) is also affected.That is, the minimum injection amount of the first fuel injection valve 7 is increased by increasing the maximum injection amount of the first fuel injection valve 7 compared to the minimum injection amount of the fuel injection valve used with other gaseous fuels (for example, LPG or the like).

[0020] When the minimum injection amount of the first fuel injection valve 7 tends to increase as described above, for example, when the flow rate of the fuel to be supplied to the internal combustion engine 1 is small, such as during idling, the flow rate of the fuel to be supplied to the internal combustion engine 1 may be smaller than the minimum injection amount of the first fuel injection valve 7. Therefore, the fuel supply device 100 has a second fuel injection valve 9 with a minimum injection amount smaller than the minimum injection amount of the first fuel injection valve 7.

[0021] The second fuel injection valve 9 is a fuel injection valve for supplying fuel at a flow rate lower than the minimum injection amount of the first fuel injection valve 7 in the internal combustion engine 1 that uses hydrogen as fuel. The minimum injection amount of the second fuel injection valve 9 is smaller than the minimum injection amount of the first fuel injection valve 7. The minimum injection amount of the second fuel injection valve 9 may, for example, be equal to or lower than the minimum fuel flow rate, which is the combustion limit on the low-load side of the internal combustion engine 1, so as to be able to cover the flow rate on the low-flow rate side of the fuel to be supplied to the internal combustion engine 1. The minimum fuel flow rate can be determined, for example, through a bench test of an internal combustion engine 1 or the like.The maximum injection quantity of the second fuel injection valve 9 may be equal to or greater than the minimum injection quantity of the first fuel injection valve 7.

[0022] In the example of Fig. 1, the second fuel injection valve 9 is provided on the intake manifold 50. Specifically, the second fuel injection valve 9 is provided on the inlet portion 51 of the intake manifold 50 so as to inject fuel from the inlet portion 51 toward the guide portion 54. Unlike the first fuel injection valve 7, hydrogen is supplied from the fuel tank to the second fuel injection valve 9 without passing through the rail 8. By providing the second fuel injection valve 9 in the intake manifold 50 as described above, it is possible to suppress restriction of the degree of freedom in layout, for example, by installing the rail or the like, compared with a configuration in which additional injectors corresponding to the number of cylinders are provided in the intake port portion 5b.

[0023] The fuel supply device 100 includes an electronic control unit (ECU) 10. The electronic control unit (ECU) 10 is an electronic control unit that controls the internal combustion engine 1. The electronic control unit (ECU) 10 includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), a communication circuit, and the like. In the electronic control unit (ECU) 10, for example, a program stored in the ROM is loaded into the RAM, and the program loaded into the RAM is executed by the CPU to implement various functions. The electronic control unit (ECU) 10 may be composed of a plurality of electronic units.

[0024] The electronic control unit (ECU) 10 controls the first fuel injection valve 7 and the second fuel injection valve 9. A functional example and a processing example of the electronic control unit (ECU) 10 will be described with reference to Fig. 3 and Fig. 4 described. Fig. 3 is a flowchart showing a processing example of fuel injection by the electronic control unit (ECU) of Fig. 1. The processing of Fig. 3 is carried out while the combustion engine 1 is running.

[0025] As in Fig. As illustrated in FIG. 3, the electronic control unit (ECU) 10 calculates the fuel injection flow rate in S01. The electronic control unit (ECU) 10 calculates the fuel injection flow rate based, for example, on a detection signal from an engine speed sensor that detects the engine speed of the internal combustion engine 1 and a detection signal from an intake amount sensor that detects a detection value related to the intake amount of the internal combustion engine 1. A known configuration (for example, a crank angle sensor or the like) may be used as the engine speed sensor. A known configuration (for example, an intake negative pressure sensor, an air flow sensor, or the like) may be used as the intake amount sensor.

[0026] In S02, the electronic control unit (ECU) 10 determines whether a predetermined low flow rate condition is met. The low flow rate condition is a condition for switching whether fuel is injected through the second fuel injection valve 9. For example, the electronic control unit (ECU) 10 may determine whether the low flow rate condition is met based on whether the calculated fuel injection flow rate is less than the minimum injection amount of the first fuel injection valve 7.

[0027] If it is determined that the low flow rate condition is satisfied (S02: YES), the electronic control unit (ECU) 10 performs fuel injection at the calculated fuel injection flow rate using the second fuel injection valve 9 in S03. That is, if a predetermined low flow rate condition is satisfied, the electronic control unit (ECU) 10 causes the second fuel injection valve 9 to inject fuel instead of the first fuel injection valve 7. Thereafter, the electronic control unit (ECU) 10 ends the processing of Fig. 3.

[0028] On the other hand, if it is determined that the low flow rate condition is not satisfied (S02: NO), the electronic control unit (ECU) 10 performs fuel injection at the calculated fuel injection flow rate using the first fuel injection valve 7 in S04. In this case, the electronic control unit (ECU) 10 may perform fuel injection using both the first fuel injection valve 7 and the second fuel injection valve 9 in combination. Thereafter, the electronic control unit (ECU) 10 terminates the processing of Fig. 3.

[0029] The electronic control unit (ECU) 10 can learn injection quantity fluctuation among a plurality of first fuel injection valves 7. The injection quantity fluctuation means a fluctuation in the injection quantity of fuel for each cylinder 2. The injection quantity fluctuation is caused, for example, by manufacturing tolerances of the first fuel injection valve 7 or the like. In the fuel supply device 100 including the second fuel injection valve 9 in addition to the plurality of first fuel injection valves 7, during fuel injection of the second fuel injection valve 9, the fuel injected by the second fuel injection valve 9 can influence the injection quantity fluctuation among the first fuel injection valves 7.Therefore, the electronic control unit (ECU) 10 can learn the injection quantity fluctuation among the plurality of first fuel injection valves 7 when fuel injection by the second fuel injection valve 9 is not performed. The learning of the injection quantity fluctuation itself can be performed by a known learning method based on, for example, the engine speed fluctuation for each cylinder 2.

[0030] Fig. 4 is a flowchart showing a processing example of the injection quantity fluctuation learning of the electronic control unit (ECU) in Fig. 1. As in Fig. 4, the electronic control unit (ECU) 10, in S11, calculates the fuel injection flow rate similar to S01 of Fig. 3.

[0031] In S12, the electronic control unit (ECU) 10, similar to S02 of Fig. 3, whether a predetermined low flow rate condition is met or not.

[0032] When it is determined that the low flow rate condition is satisfied (S12: YES), the electronic control unit (ECU) 10 terminates the processing of Fig. 3, without performing the learning of the injection quantity fluctuation among the plurality of first fuel injection valves 7. On the other hand, if it is determined that the low flow rate condition is not satisfied (S12: NO), the electronic control unit (ECU) 10 performs the learning of the injection quantity fluctuation among the plurality of first fuel injection valves 7 in S13. Thereafter, the electronic control unit (ECU) 10 ends the processing of Fig. 3. [Operation and effects]

[0033] In the fuel supply device 100 as described above, for example, when the flow rate of the fuel to be supplied to the internal combustion engine 1 is low, such as during idling, the second fuel injection valve 9 is used, so that it is possible to supply the fuel at a flow rate smaller than the minimum injection amount of the first fuel injection valve 7. Thus, according to the fuel supply device 100, even when the fuel flow rate to be injected through the fuel injection valve is low in the internal combustion engine 1 using hydrogen as fuel, the fuel can be supplied appropriately.

[0034] In the fuel supply device 100, the intake manifold 50 communicates with the inlet portion 51, which is an upstream intake port on the upstream side, and the intake ports 52, which are two or more downstream intake ports on the downstream side. The intake manifold 50 has the guide portion 54 that guides intake air so as to distribute the intake air flowing through the inlet portion 51 to the individual intake ports 52. The second fuel injection valve 9 is provided in the intake manifold 50 so as to inject fuel from the inlet portion 51 toward the guide portion 54. Thereby, the fuel injected from the second fuel injection valve 9 is more reliably guided through the guide portion 54. The fuel injected from the second fuel injection valve 9 is easily and appropriately distributed to the plurality of cylinders 2.

[0035] The second fuel injection valve 9 is provided in the intake manifold 50, so it is possible to suppress the limitation of the degree of freedom in layout by, for example, installing the rail or the like, compared to a configuration in which additional injectors corresponding to the number of cylinders are provided in the intake port portion 5b. This increases the degree of freedom in installation. Furthermore, costs can be reduced by reducing the number of second fuel injection valves 9.

[0036] The fuel supply device 100 further includes the electronic control unit (ECU) 10, which controls the first fuel injection valve 7 and the second fuel injection valve 9. The electronic control unit (ECU) 10 causes the second fuel injection valve 9 to inject fuel when a predetermined low flow rate condition is met. The electronic control unit (ECU) 10 learns the injection quantity fluctuation among the plurality of first fuel injection valves 7 when the low flow rate condition is not met.

[0037] As a result, in the internal combustion engine 1 having the first fuel injection valve 7 and the second fuel injection valve 9, the inter-cylinder fluctuation can be appropriately learned. [Modification]

[0038] Although the embodiments according to the present disclosure have been described above, the present disclosure is not limited to the embodiments described above.

[0039] In the above embodiments, the second fuel injection valve 9 is provided in the intake manifold 50 and is located on the downstream side of the throttle valve 5c, but the invention is not limited thereto. For example, as in a fuel supply device 100A of Fig. 5, the second fuel injection valve 9 may be provided on the upstream side of the throttle valve 5c in the single-pipe section 5a. As an example of the branch section, the 1-2-4 type intake manifold 50 having tubular intake ports is cited, but the branch section is not limited to this. The branch section may be, for example, a 1-4 type intake manifold. The branch section may have a volume proportion corresponding to a surge tank, taking backfiring into account. The internal combustion engine may have a plurality of cylinders other than four. The branch section may be an intake manifold corresponding to the number of cylinders other than four. In short, the second fuel injection valve should be provided in the single-pipe section or the branch section.

[0040] In the above embodiments, the second fuel injection valve 9 is provided at the inlet portion 51 of the intake manifold 50 so as to inject fuel from the inlet portion 51 toward the guide portion 54, but the invention is not limited thereto. For example, as in a fuel supply device 100B of Fig. 6, the second fuel injection valve 9 may be provided in each of the pair of second branch sections 50b. In this case, the fuel injected from the second fuel injection valve 9 reaches the interior of the cylinder 2 earlier compared to / with the case where the second fuel injection valve 9 is provided in the first branch section 50a. This makes it possible to improve the responsiveness of the internal combustion engine 1. In the example of Fig.6, the second branching portion 50b does not have a guide portion, but the invention is not limited thereto. The second branching portion 50b may have a guide portion.

[0041] In the above embodiments, the first fuel injection valve 7 is the primary fuel injection valve in the internal combustion engine 1 that uses hydrogen as fuel, but the invention is not limited thereto. The second fuel injection valve 9 may be a primary fuel injection valve. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2023-123264 A

[0002] JP 2011-058435 A

[0003]

Claims

[1] Fuel supply device for a four-stroke internal combustion engine using hydrogen as fuel and having a plurality of cylinders, comprising: - an intake port having a branch portion branching from an upstream side toward a downstream side so as to correspond to the number of cylinders, a single pipe portion on an upstream side of the branch portion, and intake port portions on a downstream side of the branch portion; and - a plurality of first fuel injection valves provided in each of the intake port portions, wherein a maximum injection period of the first fuel injection valve is a value corresponding to a valve opening period of an intake valve of the internal combustion engine; a second fuel injection valve is provided in the single pipe section or the branch section; and a minimum injection quantity of the second fuel injection valve is smaller than a minimum injection quantity of the first fuel injection valve. [2] Fuel supply device according to claim 1, wherein the branching section has a guide section; the guide portion communicates with an upstream intake passage on an upstream side and with two or more downstream intake passages on a downstream side and guides intake air so as to distribute the intake air flowing through the upstream intake passage to each of the downstream intake passages; and the second fuel injection valve is provided in the branching portion so as to inject the fuel from the upstream intake passage toward the guide portion. [3] Fuel supply device according to claim 1 or 2, wherein the branching portion comprises a first branching portion branching from one intake port into two intake ports, and a pair of second branching portions further branching from the two intake ports on a downstream side of the first branching portion into two intake ports each, and the second fuel injection valve is provided in each of the pair of second branch portions. [4] Fuel supply device according to one of claims 1 to 3, further comprising: - a control unit configured to control the first fuel injection valve and the second fuel injection valve, wherein the control unit causing the second fuel injection valve to inject the fuel when a predetermined low flow rate condition is met, and learns an injection quantity fluctuation among the plurality of first fuel injectors when the low flow rate condition is not met.

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