Fuel supply device for internal combustion engine

Abstract

The invention provides a fuel supply device for an internal combustion engine. The fuel supply device enables a valve body of a solenoid valve arranged in a fuel passage to be rapidly opened. A fuel supply device (300) is provided with: a second shut-off valve (22) that is provided in a fuel pipe (40) of an internal combustion engine, has a valve body, and opens when the pressure difference between the upstream side and the downstream side of the valve body in the direction of flow of fuel in the fuel pipe (40) is equal to or less than a predetermined value; a bypass pipe (400) connected to the fuel pipe (40) upstream of the second shut-off valve (22) and the fuel pipe (40) downstream of the second shut-off valve (22) when viewed in the direction of flow of the fuel; and a bypass valve (410) that is provided to the bypass piping (400) and that opens when there is a request to open the valve body of the second shut-off valve (22).

Description

Technical Field

[0001] This invention relates to a fuel supply device for an internal combustion engine. Background Technology

[0002] For example, the fuel supply device for an internal combustion engine described in Patent Document 1 has a shut-off valve, which functions as a solenoid valve, in the fuel passage connecting the fuel tank and the fuel injection valve. Furthermore, during the starting of the internal combustion engine, the starting performance is improved by supplying gaseous fuel at the required pressure to the fuel injection valve through appropriate control of the opening timing of the shut-off valve.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-118842 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] By configuring the solenoid valve so that it opens when the pressure difference between the upstream and downstream sides of the valve core falls below a predetermined value, the magnetic force required to open the solenoid valve can be reduced. If the required magnetic force to open the valve is reduced, for example, the solenoid valve can be miniaturized or its power consumption reduced. However, in this case, when utilizing such a pressure difference, the pressure difference exceeds the predetermined value during valve closure. Therefore, when opening the valve, time is required until the pressure difference falls below the predetermined value, making it potentially difficult to quickly open the solenoid valve core.

[0008] Methods for solving problems

[0009] A fuel supply device for an internal combustion engine that solves the above-mentioned problems includes: a solenoid valve disposed in the fuel passage of the internal combustion engine and having a valve core, which opens when the pressure difference between the upstream and downstream sides of the valve core in the direction of fuel flow in the fuel passage becomes less than a predetermined value; a bypass flow path connected upstream and downstream of the solenoid valve in the direction of fuel flow in the fuel passage; and a bypass valve disposed in the bypass flow path, which opens when there is a valve opening requirement from the valve core.

[0010] Invention Effects

[0011] The fuel supply device of this internal combustion engine enables the valve core of the solenoid valve located in the fuel passage to open rapidly. Attached Figure Description

[0012] Figure 1 This is a schematic diagram showing an internal combustion engine, a fuel supply system, and a control device for an internal combustion engine in one embodiment.

[0013] Figure 2This is a cross-sectional view showing the structure of the second shut-off valve in this embodiment.

[0014] Figure 3 This is a flowchart illustrating the steps of the processing performed by the control device in this embodiment.

[0015] Explanation of reference numerals in the attached figures

[0016] 10…Internal combustion engine 20…Tank 21…First shut-off valve 22…Second shut-off valve 22…Second valve 30…Pressure reducing valve 40…Fuel piping 60…Delivery pipe 100…Control device 210…First valve 220…Second valve 300…Fuel supply device 400…Bypass piping 410…Bypass valve. Detailed Implementation

[0017] The following is for reference Figures 1-3 An embodiment of a fuel supply device for an internal combustion engine will be described.

[0018] Internal combustion engine, fuel supply device, and control device

[0019] Figure 1 The internal combustion engine 10 shown is mounted in a vehicle and is an internal combustion engine that uses hydrogen as fuel, which is a fluid gaseous fuel.

[0020] A throttle valve 12 for adjusting the intake air volume is provided in the intake passage 11 of the internal combustion engine 10.

[0021] The internal combustion engine 10 has a fuel supply device 300 including a fuel injection valve 15, a tank 20, a fuel pipe 40, a first shut-off valve 21, a second shut-off valve 22, a pressure reducing valve 30, a delivery pipe 60, a bypass pipe 400, and a bypass valve 410.

[0022] Fuel injection valve 15 supplies fuel to cylinder 10a of internal combustion engine 10. Tank 20 stores hydrogen as a gaseous fuel under high pressure. Fuel line 40 connects tank 20 to delivery line 60. Delivery line 60 is connected to fuel injection valve 15. Fuel line 40 and delivery line 60 form the fuel passage connecting tank 20 to fuel injection valve 15. Hydrogen stored in tank 20 is supplied to fuel injection valve 15 via fuel line 40 and delivery line 60.

[0023] On the fuel piping 40, a first shut-off valve 21, a pressure reducing valve 30, and a second shut-off valve 22 are arranged sequentially in the direction of fuel flow.

[0024] The first shut-off valve 21 is a solenoid valve located near the outlet of tank 20. When the first shut-off valve 21 is open, fuel is supplied from tank 20 to fuel line 40. When the first shut-off valve 21 is closed, fuel supply from tank 20 to fuel line 40 is stopped. The pressure reducing valve 30 is used to reduce the fuel pressure (fuel pressure) of hydrogen stored in tank 20 under high pressure to a specified pressure (e.g., about 4 MPa) and supply it to fuel injection valve 15. The second shut-off valve 22 is a solenoid valve located near delivery pipe 60 in fuel line 40. When the second shut-off valve 22 is open by energization, fuel is supplied to delivery pipe 60. When the second shut-off valve 22 is closed by energization de-energization, fuel supply to delivery pipe 60 is stopped.

[0025] The first shut-off valve 21 and the second shut-off valve 22 are closed when the internal combustion engine 10 is stopped. On the other hand, the first shut-off valve 21 and the second shut-off valve 22 are basically open when the internal combustion engine 10 is running.

[0026] A first pressure sensor 81, located on the fuel line 40 between the first shut-off valve 21 and the pressure reducing valve 30, detects the fuel pressure (first pressure P1) within the fuel line 40. A second pressure sensor 82, located on the fuel line 40 between the pressure reducing valve 30 and the second shut-off valve 22, detects the fuel pressure (second pressure P2) within the fuel line 40. A third pressure sensor 83, located on the delivery pipe 60, detects the fuel pressure (third pressure P3) within the delivery pipe 60. A temperature sensor 84, located on the delivery pipe 60, detects the fuel temperature (THF) within the delivery pipe 60.

[0027] The bypass pipe 400 forms a bypass flow path, which, when viewed along the fuel flow direction, is connected to the fuel pipe 40 upstream of the second shut-off valve 22 and the fuel pipe 40 downstream of the second shut-off valve 22.

[0028] Bypass valve 410 is a solenoid valve located in bypass piping 400. When bypass valve 410 is open, fuel flows within bypass piping 400. When bypass valve 410 is closed, the flow of fuel within bypass piping 400 is cut off.

[0029] The control device 100 performs various controls on the internal combustion engine 10, such as fuel injection, by controlling various control objects, including the throttle valve 12, fuel injection valve 15, first shut-off valve 21, second shut-off valve 22, and bypass valve 410. The control device 100 includes a memory 120 composed of a CPU 110, ROM, and RAM, and performs various controls by executing programs stored in the memory 120 through the CPU 110.

[0030] The control device 100 references various values ​​required for controlling the internal combustion engine 10. For example, the control device 100 references the detection values ​​of the first pressure sensor 81, the second pressure sensor 82, the third pressure sensor 83, and the temperature sensor 84. Additionally, the control device 100 references the detection signal of the accelerator position sensor 71, which detects the amount of operation of the accelerator pedal 27 by the driver of the vehicle equipped with the internal combustion engine 10, i.e., the accelerator operation amount ACCP. Furthermore, the control device 100 references the detection signal of the speed sensor 72, which detects the vehicle speed SP of the vehicle equipped with the internal combustion engine 10. Additionally, the control device 100 references the detection signal of the airflow meter 73, which detects the intake air volume GA of the internal combustion engine 10, and the detection signal Scr of the crankshaft angle sensor 74, which detects the crankshaft rotation angle of the internal combustion engine 10.

[0031] <Fuel Pressure Control>

[0032] The control device 100 performs fuel pressure control, in which the pressure of the fuel supplied to the fuel injection valve 15, i.e., the fuel pressure in the fuel passage connected downstream of the second shut-off valve 22 in the fuel flow direction, is controlled. This fuel pressure control involves repeatedly controlling the opening and closing of the second shut-off valve 22 to ensure that the fuel pressure in the fuel passage connected downstream of the second shut-off valve 22 is within a control range CR defined by a predetermined upper limit value PtU and a predetermined lower limit value PtL. The target pressure Pt in the fuel pressure control is a pressure lower than the fuel pressure reduced by the pressure reducing valve 30, i.e., the second pressure P2, and is preset. For example, the target pressure Pt is approximately 1 MPa. Furthermore, the upper limit of the fuel pressure that can be tolerated relative to the target pressure Pt is set to the aforementioned upper limit value PtU. Additionally, the lower limit of the fuel pressure that can be tolerated relative to the target pressure Pt is set to the aforementioned lower limit value PtL.

[0033] It should be noted that, for example, fuel pressure control is performed when the internal combustion engine 10 switches from an operating state to an idling state. When the injection quantity of the fuel injection valve 15 decreases, such as during idling, fuel pressure control is implemented to maintain the fuel pressure in the delivery pipe 60, i.e., the third pressure P3, at a pressure lower than the second pressure P2, thereby injecting a small amount of fuel from the fuel injection valve 15 with high precision.

[0034] On the other hand, when the operating state of the internal combustion engine 10 shifts to a normal operating state where the engine load is higher than the idle operating state, the fuel pressure control of the second shut-off valve 22 is stopped. As a result, the periodic opening and closing drive of the second shut-off valve 22 ceases, and the second shut-off valve 22 remains open. During the opening of the second shut-off valve 22, fuel is supplied from the tank 20 to the delivery pipe 60, thus the third pressure P3 gradually increases towards the normal operating pressure, i.e., the second pressure P2.

[0035] <Structure of the second shut-off valve>

[0036] Figure 2 The structure of the second shut-off valve 22 is shown. It should be noted that, hereinafter, the direction along the central axis L of the plunger 211 of the second shut-off valve 22 will be referred to as the axial direction. Furthermore, the direction orthogonal to the axial direction will be referred to as the radial direction.

[0037] The second shut-off valve 22 includes a housing 200, a stator 230, an electromagnetic coil 240, a first valve 210, a bracket 250, and a second valve 220.

[0038] The housing 200 has an inlet port 201 connected to the fuel line 40 connected to the pressure reducing valve 30 and an outlet port 203 connected to the fuel line 40 connected to the delivery pipe 60.

[0039] The inlet port 201 and the outlet port 203 are connected via a space formed within the housing 200, namely the first chamber 202.

[0040] The stator 230 is cylindrical and is housed inside the housing 200.

[0041] The electromagnetic coil 240 is located on the outer periphery of the stator 230. The electromagnetic coil 240 opens the valve core by being energized.

[0042] The first valve 210, which is the first valve core, includes: a plunger 211 that moves axially within the stator 230; and a first sealing member 213 that opens and closes the first fuel passage 222 by moving the plunger 211.

[0043] One end of the plunger 211 becomes a protrusion 212 protruding from the stator 230. The aforementioned first sealing member 213 is provided at the top of the protrusion 212. In addition, the protrusion 212 has a pin 214 extending radially. Both ends of the pin 214 protrude from the outer peripheral surface of the protrusion 212.

[0044] The bracket 250 has a cylindrical portion 251 coaxial with the central axis L. The inner peripheral surface of the cylindrical portion 251 faces and is separate from the outer peripheral surface of the aforementioned protrusion 212.

[0045] The second valve 220, serving as the second valve core, is slidably housed on the inner circumferential surface of the cylindrical portion 251. The second valve 220 has a hole 221 for sliding on the outer circumferential surface of the protrusion 212 of the first valve 210. The second valve 220 also has an elongated hole 225 for inserting the aforementioned pin 214 and allowing the pin 214 to move axially.

[0046] A first fuel passage 222 extending axially is formed at the top of the second valve 220. The first fuel passage 222 is connected to the outlet port 203 constituting the second fuel passage. The outlet port 203 is a fuel passage with a flow path cross-sectional area larger than that of the first fuel passage 222.

[0047] A second sealing component 224 for opening and closing the outlet port 203 is provided at the top of the second valve 220. More specifically, the second sealing component 224 opens and closes the second valve seat 204 located at one end of the outlet port 203.

[0048] A first valve seat 223 protruding toward the protrusion 212 is formed at the top of the second valve 220, which forms the first fuel passage 222. The first valve seat 223 is opened and closed by the first sealing member 213, thereby opening and closing the first fuel passage 222. The first fuel passage 222 becomes a connecting passage that connects the flow path upstream of the second valve 220 (which is the second valve core) with the flow path downstream of the second valve 220. The flow path upstream of the second valve 220 includes the pressure chamber 227 (described later), the connecting passage 226 (described later), the first chamber 202, and the inlet port 201. The flow path downstream of the second valve 220 is the outlet port 203. The first valve 210 is the first valve core that opens before the second valve 220 opens and opens and closes the first fuel passage 222.

[0049] In the orifice 221, the space surrounded by the walls surrounding the first valve seat 223 and the top surface of the protrusion 212 becomes a pressure chamber 227 that exerts pressure on the second valve 220 in the closing direction. This pressure chamber 227 is connected to the first chamber 202 via a connecting passage 226.

[0050] A second chamber 255 is formed on the inner circumferential surface of the cylindrical portion 251 of the bracket 250 to ensure the axial stroke of the second valve 220.

[0051] When the second valve 220 is fully open, the end face 228 on the side opposite to the side where the second sealing member 224 is disposed and the limiting portion 253 in the bracket 250, which is formed by the surface opposite to the end face 228, abut against each other. By maintaining these end faces 228 and limiting portions 253 in abutment, the position of the valve core when the second valve 220 is fully open is stabilized.

[0052] An end cap 280 is provided inside the stator 230 at the end opposite to the side where the plunger 211 is inserted, to close that end. A third chamber 257 is formed between the end cap 280 and the plunger 211 as a space. In addition, a spring 215 is provided between the end cap 280 and the plunger 211 to apply force to the plunger 211 in a direction away from the end cap 280.

[0053] <Opening and closing action of the second shut-off valve>

[0054] By energizing the electromagnetic coil 240, when the plunger 211 is pulled into the stator 230, the first valve 210 moves in the direction in which the first sealing member 213 separates from the first valve seat 223, thereby opening the first valve 210. When the first sealing member 213 separates from the first valve seat 223, fuel flowing in from the inlet port 201 flows into the outlet port 203 via the first chamber 202, the connecting passage 226, the pressure chamber 227, and the first fuel passage 222.

[0055] Furthermore, the first valve 210 moves in the direction in which the first sealing member 213 separates from the first valve seat 223, thereby causing the pin 214 of the first valve 210 to abut against the wall surface 229 of the elongated hole 225 of the second valve 220, which is axially located in the opening direction of the first valve 210. Therefore, an opening force Fop is applied to the second valve 220 in the same direction as the movement of the first valve 210. This opening force Fop is an attractive force generated by the magnetic force of the electromagnetic coil 240, acting in the opening direction of the second valve 220.

[0056] When the first valve 210 opens, the pressure chamber 227 connects to the outlet port 203, thus reducing the pressure difference between the pressure chamber 227 and the outlet port 203. Consequently, the force resisting the opening of the second valve 220, i.e., the resistance Fcl, decreases. It should be noted that the resistance Fcl includes the force acting in the closing direction of the second valve 220, the sliding resistance of the second valve 220 and the support 250, etc. Furthermore, the force acting in the closing direction of the second valve 220 includes the differential pressure load generated by the pressure difference between the pressure chamber 227 and the outlet port 203, and the force of the spring 215.

[0057] The differential pressure load is reduced by opening the first valve 210. If the opening force Fop is greater than the resistance Fcl, the second valve 220 moves in the direction that the second sealing member 224 separates from the second valve seat 204. This movement of the second valve 220 constitutes its opening action. When the second sealing member 224 separates from the second valve seat 204, the fuel flowing in from the inlet port 201 flows primarily through the first chamber 202 into the outlet port 203.

[0058] When the second valve 220 is fully open, the end face 228 abuts against the limiting part 253, thereby stopping the axial movement of the second valve 220.

[0059] Fuel flowing into outlet port 203 is delivered to fuel injection valve 15 via fuel pipe 40 and delivery pipe 60.

[0060] When the energization of the electromagnetic coil 240 is stopped, the first valve 210 moves in the direction where the first sealing member 213 abuts against the first valve seat 223 due to the force of the spring 215, etc. Thus, the first valve 210 closes.

[0061] When the first sealing member 213 abuts against the first valve seat 223, the force of the spring 215 acts on the second valve 220. Therefore, the second valve 220 moves in the direction where the second sealing member 224 abuts against the second valve seat 204. Thus, the second valve 220 closes.

[0062] Thus, in the second shut-off valve 22, the pressure in the pressure chamber 227 is used to open and close the outlet port 203, which has a larger cross-sectional area than the first fuel passage 222. Specifically, if the pressure difference between the pressure chamber 227 (which represents the pressure difference between the upstream and downstream sides of the second valve 220) and the outlet port 203 decreases to a predetermined value, the second valve 220 opens. Therefore, compared to directly using the magnetic force of the electromagnetic coil to open the second valve 220, the magnetic force required for opening can be reduced. This allows for miniaturization of the electromagnetic coil 240. It should be noted that in this embodiment, the attractive force of the electromagnetic coil 240 is set, for example, so that the second valve 220 opens when the aforementioned pressure difference is approximately "0". That is, the force in the resistance Fcl that overcomes the sliding resistance between the second valve 220 and the support 250, as well as the force of the spring 215, is set as the attractive force.

[0063] Furthermore, in the second shut-off valve 22, the first valve 210 is used for small-flow fuel adjustment. Therefore, the aforementioned fuel pressure control is implemented by opening and closing the first valve 210. Additionally, in an operating state where the internal combustion engine load is higher than the idle speed, the second valve 220 is opened.

[0064] <Bypass valve opening and closing control>

[0065] Figure 3 This indicates the steps performed by the control device 100 to control the opening and closing of the bypass valve 410. It should be noted that, below, step numbers are indicated by numbers beginning with "S".

[0066] When this process begins, the control device 100 determines whether there is a valve opening requirement for the second valve 220 (S100). The valve opening requirement for the second valve 220 is required, for example, when the internal combustion engine is started or when the aforementioned fuel pressure control ends.

[0067] If it is determined that there is a requirement to open the second valve 220 (S100: Yes), the control device 100 opens the bypass valve 410 (S110).

[0068] Next, the control device 100 determines whether the second valve 220 is fully open (S120). The full-open determination in S120 can be performed appropriately. For example, if the second valve 220 is fully open, the actual current flowing through the solenoid coil 240 temporarily decreases. Therefore, if a temporary decrease in the actual current is detected, it can be determined that the second valve 220 is fully open. Furthermore, when the second valve 220 is fully open, the third pressure P3 remains equal to the second pressure P2. Therefore, if such a movement of the third pressure P3 is detected, it can be determined that the second valve 220 is fully open.

[0069] Then, the control device 100 repeatedly executes each of the processes in S110 and S120 until a positive determination is made in the process of S120.

[0070] If a positive determination is made in the above-mentioned S120 process, the control device 100 closes the bypass valve 410 (S130).

[0071] If the process of S130 is executed, or if a negative determination is made in the process of S100, the control device 100 terminates the process.

[0072] <Function and Effects of This Implementation Method>

[0073] (1) When there is a demand to open the second valve 220 of the second shut-off valve 22 provided in the fuel line 40, the bypass valve 410 provided in the bypass line 400 opens. When the bypass valve 410 opens, the upstream and downstream sides of the second valve 220 are connected via the bypass line 400. Therefore, fuel flows from the upstream side of the second valve 220 to the downstream side. When fuel flows in this way, the pressure on the downstream side of the second valve 220 rises rapidly towards the pressure on the upstream side of the second valve 220, and therefore the pressure difference between the upstream and downstream sides of the second valve 220 decreases rapidly. Therefore, when there is a demand to open the second valve 220, the second valve 220 opens rapidly.

[0074] (2) If a delay in opening the second valve 220 occurs during engine starting, the fuel flow required for engine starting cannot be adequately ensured, and the engine starting time may become longer. In this embodiment, the opening requirement of the second valve 220 is specified during engine starting. Therefore, the second valve 220 opens rapidly during engine starting. This prevents the engine starting time from becoming longer.

[0075] (3) The opening requirement of the second valve 220 is required at the end of the above-mentioned fuel pressure control. Therefore, at the end of the above-mentioned fuel pressure control, the second valve 220 opens rapidly. Therefore, the third pressure P3, which has become a pressure lower than the second pressure P2 due to the implementation of fuel pressure control, can be quickly restored to the second pressure P2. Therefore, for example, a rapid recovery from idle operation to normal operation is possible.

[0076] <Example of Change>

[0077] It should be noted that the above embodiments can be implemented by modification as follows. The above embodiments and the following modifications can be combined with each other within the scope of technical inconsistency.

[0078] The bypass piping 400 can also be configured as a bypass flow path that connects the fuel piping 40 upstream of the second shut-off valve 22 to the delivery pipe 60.

[0079] The second shut-off valve 22 may also omit the first valve 210. In this case, the second valve 220 can be directly opened and closed using the solenoid coil 240. In this modified example, when the second valve 220 is required to open, the bypass valve 410 opens, and thus the pressure difference between the upstream and downstream sides of the second valve 220 quickly falls below a predetermined value. Therefore, the second valve 220 opens rapidly.

[0080] • When the above-mentioned fuel pressure control is not performed, the bypass valve 410 can also be kept in the open state.

[0081] The fuel for the internal combustion engine 10 is hydrogen, a gaseous fuel, but it can also be other gaseous fuels, such as compressed natural gas.

[0082] The internal combustion engine 10 uses gaseous fuel, but it can also use liquid fuel.

[0083] • The flow path of the fluid is the fuel passage of the internal combustion engine 10, but it can also be other flow paths.

Claims

1. A fuel supply device for an internal combustion engine, comprising: A solenoid valve is provided in the fuel passage of an internal combustion engine and has a valve core. The valve opens when the pressure difference between the upstream and downstream sides of the valve core in the direction of fuel flow in the fuel passage becomes below a predetermined value. A bypass flow path, when viewed along the fuel flow direction, connects to the fuel passage upstream of the solenoid valve and the fuel passage downstream of the solenoid valve; and A bypass valve is provided in the bypass flow path and opens when there is a valve opening requirement from the valve core.

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