JP4600231B2 - Dual fuel engine fuel switching control device - Google Patents

Description

  The present invention belongs to a technical field related to a fuel switching control device of a dual fuel engine that can switch between gaseous fuel and gasoline as a fuel to be used.

  In recent years, from the viewpoint of environmental problems and the like, a dual fuel engine has been actively developed as an engine for vehicles such as automobiles. This dual fuel engine, for example, as shown in Patent Document 1 and Patent Document 2, enables switching between gas fuel such as natural gas and gasoline as the fuel used. It is also known to use hydrogen as a gaseous fuel (see, for example, Patent Document 3).

In the dual fuel engine as described above, as disclosed in Patent Document 1, a value related to the driving state of the vehicle, such as the engine speed, is detected, and the detected value related to the detected driving state is determined. It is known to switch the used fuel. That is, when the operating state related value becomes a value larger than the predetermined value from a value less than a predetermined value set in advance, or when the operating state related value becomes a value smaller than the predetermined value from a value larger than the predetermined value Switching is executed.
Japanese Patent Laid-Open No. 5-98994 JP 7-34915 A JP 2005-155528 A

  However, if the used fuel is switched with the predetermined value set in advance as a threshold as described above, the used fuel is frequently switched depending on the driving state of the vehicle, resulting in frequent torque shocks. That is, as shown in Patent Document 2 described above, torque switching occurs due to differences in fuel properties, response delays in the control system, and the like when switching the fuel used. Unlike a torque shock that occurs during a gear shifting operation, it occurs unexpectedly for the vehicle occupant. Therefore, if such a torque shock occurs frequently, the occupant is greatly discomforted.

  The present invention has been made in view of such a point, and an object of the present invention is to provide a vehicle equipped with the dual fuel engine as described above according to a value related to a driving state of the vehicle. This is to prevent frequent switching of the used fuel when the used fuel is switched.

In order to achieve the above object, according to the present invention, the execution of the switching of the next used fuel is restricted until the predetermined time elapses from the execution of the switching of the used fuel, and the predetermined change from the execution of the switching of the used fuel is performed. When the time has elapsed, the restriction on the execution of the switching is immediately released .

  Specifically, the invention of claim 1 is directed to a fuel switching control device for a dual fuel engine that is mounted on a vehicle and that can switch between gaseous fuel and gasoline as the fuel used.

A driving state related value detecting means for detecting a value related to the driving state of the vehicle; and a fuel switching for executing fuel switching according to the driving state related value detected by the driving state related value detecting means. and means, between the execution of switching of the fuel used by the fuel used switching means until a predetermined time elapses, and a restricting means for restricting execution of switching subsequent use fuel by the fuel switching means for said use, the limit The means is configured to immediately release the restriction on the execution of the switching when a predetermined time has elapsed from the execution of the switching of the used fuel by the used fuel switching means .

  With the above configuration, when switching of the fuel to be used is performed, execution of the next switching is limited until a predetermined time elapses from the execution of the switching, that is, it becomes difficult to perform the next switching, Or execution of the next switching is prohibited. As a result, the fuel used does not frequently switch, and torque shock due to switching does not occur frequently.

According to a second aspect of the present invention, in the first aspect of the present invention, the gaseous fuel tank for storing the gaseous fuel, and the gaseous fuel tank and the gaseous fuel supply means for supplying the gaseous fuel to the combustion chamber of the engine are connected. A gaseous fuel supply path; and a control valve provided in the gaseous fuel supply path and controlled by the used fuel switching means . The used fuel switching means is detected by the operating state related value detecting means. When the operating state related value becomes a value larger than the predetermined value from a value equal to or less than the predetermined value, the fuel used is switched from gas fuel to gasoline, while the predetermined value is increased from a value larger than the predetermined value. when it becomes the following values is configured to perform the switching of fuel used from gasoline to gaseous fuel, said limiting means, from the gaseous fuel by the fuel used switching means Only during the execution of the switching of the fuel used to Sorin until a predetermined time elapses, thereby limiting the execution of the switching of the fuel used in the following gasoline to gaseous fuel by the fuel switching means for said use, the fuel used switching means After the execution of the switching of the used fuel from the gasoline to the gaseous fuel by the above, it is assumed that the execution of the switching of the used fuel from the next gaseous fuel to the gasoline by the used fuel switching means is not limited .

In other words, the control valve is usually provided to prevent gaseous fuel from leaking from the gaseous fuel supply path, but when switching from gasoline to gaseous fuel, a response delay of the control valve occurs, and this response delay causes Large torque shock is likely to occur. In addition, if the used fuel is frequently switched, the occupant is more likely to feel discomfort. However, in the present invention, the execution of the switching of the used fuel from the gasoline to the gaseous fuel is limited until the predetermined time has elapsed since the execution of the switching of the used fuel from the gaseous fuel to the gasoline. It is possible to prevent the passengers from feeling uncomfortable as much as possible. On the other hand, switching from gas fuel to gasoline is because high output and high torque are required. Therefore, if the next switching is from gas fuel to gasoline, this switching is not restricted, so that high output or high It becomes possible to respond quickly to the torque request. Moreover, when switching from gas fuel to gasoline, torque shock is relatively small and does not pose a major problem.

In the invention of claim 3, characterized in that in the invention of claim 2, upper Symbol limiting means between the execution of the switching of the fuel used in gasoline from the gaseous fuel by the fuel used switching means until a predetermined time elapses, the predetermined It is assumed that the execution of the switching of the used fuel from the next gasoline to the gaseous fuel by the used fuel switching means is limited by decreasing the value.

  As a result, the predetermined value becomes small and it is difficult to switch from gasoline to gaseous fuel until a predetermined time elapses from the execution of switching of the fuel used from gaseous fuel to gasoline. Therefore, it is possible to easily limit the execution of switching from gasoline to gaseous fuel.

  According to a fourth aspect of the invention, in the first or second aspect of the invention, the limiting means is configured to restrict the execution of the switching of the next used fuel by the used fuel switching means. To do.

  This can more reliably prevent frequent switching of the fuel used.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the gaseous fuel is hydrogen, and an exhaust gas recirculation means for recirculating the exhaust gas of the engine is provided in the intake passage of the engine. The means is configured to make the exhaust gas recirculation rate higher when the fuel used is hydrogen than when the fuel used is gasoline.

  That is, when the gaseous fuel is hydrogen, since hydrogen has good ignitability, when the hydrogen concentration in the combustion chamber increases to some extent, the phenomenon that hydrogen self-ignites before ignition (this phenomenon is called pre-ignition). Arise. In order to suppress the occurrence of this hydrogen pre-ignition, the exhaust gas recirculation rate when the fuel used is hydrogen is made higher than when the fuel used is gasoline. On the other hand, at the time of transition from gasoline to hydrogen, the exhaust gas recirculation rate must be greatly changed, resulting in a response delay of an actuator that drives the exhaust gas recirculation valve provided in the exhaust gas recirculation passage. It does not increase immediately, during which hydrogen pre-ignition is likely to occur and a large torque shock is likely to occur. In addition, if the used fuel is frequently switched, the occupant is more likely to feel discomfort. However, in the present invention, since the switching of the fuel to be used does not occur frequently, it is possible to prevent the passenger from feeling as uncomfortable as possible by the torque shock. In particular, in the configuration of claim 2, when switching from gasoline to hydrogen, a considerably large torque shock is likely to occur due to the occurrence of hydrogen pre-ignition, but the next switching from gasoline to hydrogen is executed. By limiting, it is possible to prevent the passengers from feeling uncomfortable due to torque shock as much as possible.

As described above, according to the fuel switching controller of dual-fuel engine of the present invention, during the execution of the switching of the fuel used until a predetermined time elapses, thereby limiting the execution of the switching of the next fuel used, use When the predetermined time has elapsed since the fuel switch was executed, the restriction on the execution of the switch was immediately canceled, so that the fuel used was not frequently changed, and the passenger felt as uncomfortable as possible from the torque shock. You can avoid it.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 schematically shows the configuration of a fuel switching control device for a dual fuel engine according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes a rotary engine. The rotary engine 1 is mounted on a vehicle such as an automobile, and can switch between gaseous fuel (hydrogen in this embodiment) and gasoline as the fuel used. It is considered as a dual fuel engine.

  The rotary engine 1 includes a rotor housing chamber (hereinafter referred to as a cylinder) 11 surrounded by a bowl-shaped rotor housing having a trochoid inner peripheral surface and a side housing, and a substantially triangular rotor 12 accommodated therein. In addition, three working chambers are defined on the outer peripheral side of the rotor 12. Although not shown, the rotary engine 1 is formed by integrating two rotor housings so as to be sandwiched between three side housings, and the rotors 12 and 12 are accommodated in two cylinders 11 and 11 formed therebetween, respectively. In FIG. 1, the two cylinders 11 and 11 are shown in an expanded state.

  Each of the rotors 12 rotates around the eccentric shaft 13 with the seal portions respectively disposed at the three tops of the outer periphery of the rotor 12 in contact with the inner peripheral surface of the trochoid of the rotor housing. Revolves around 13 axes. Then, while the rotor 12 makes one revolution, the working chambers formed between the tops of the rotor 12 move in the circumferential direction to perform intake, compression, expansion (combustion), and exhaust strokes. Is generated from the eccentric shaft 13 via the rotor 12.

  Each cylinder 11 of the rotary engine 1 is provided with two spark plugs 14, 14. The two spark plugs 14, 14 are respectively disposed near the minor axis of the rotor housing, Each cylinder 11 is provided with two hydrogen injection injectors 4 for directly injecting hydrogen supplied from a hydrogen tank 31 (see FIG. 2) described later into the cylinder (in FIG. 1 and FIG. Each of the injectors 4 constitutes gas fuel supply means for supplying hydrogen as gaseous fuel to the combustion chamber (working chamber) of the engine 1. The two injectors 4 provided in each cylinder 11 are arranged in the axial direction of the eccentric shaft 13 in the vicinity of the long axis of the rotor housing.

  In addition, the intake passage 2 communicates with each cylinder 11 so as to communicate with the working chamber in the intake stroke, and the exhaust passage 3 communicates with the working chamber in the exhaust stroke. The intake passage 2 is one on the upstream side, but is divided into two on the downstream side and communicates with the working chambers of the cylinders 11. Further, two exhaust passages 3 are provided on the upstream side so as to communicate with the working chambers of the respective cylinders 11, but are joined together on the downstream side. A three-way catalyst 25 as an exhaust purification catalyst for purifying exhaust gas is disposed downstream of the merging portion of the exhaust passage 3 (see FIG. 2).

  A throttle valve 22 that is driven by an actuator 21 such as a stepping motor and adjusts the cross-sectional area (valve opening) of the passage 2 is disposed upstream of the branch portion of the intake passage 2. Downstream of the section, gasoline injectors 5 and 5 for injecting gasoline supplied from a later-described gasoline tank 41 (see FIG. 2) into the intake passage 2 (a branched portion) are disposed. ing.

  The ignition plugs 14, the actuators 21 of the throttle valves 22, and the injectors 4 and 5 for hydrogen and gasoline injection are controlled by a power train control module (hereinafter referred to as PCM) 6. That is, each spark plug 14 is ignited at a predetermined timing according to the rotational position of the rotor 12. Further, the actuator 21 of the throttle valve 22 is controlled by the PCM 6 in accordance with an output signal of an accelerator opening sensor 52 described later to adjust the opening of the throttle valve 22. In other words, the opening value of the throttle valve 22 corresponds to the output value of the throttle opening sensor 52 (the actuator 21 also serves as the actuator 21 in this embodiment) that detects the opening. To adjust to a predetermined value. Further, the injector 4 for hydrogen injection injects hydrogen into the cylinder 11 (working chamber) at a predetermined timing according to the rotational position of the rotor 12 when the fuel used is hydrogen, and the injector 5 for gasoline injection. Injects gasoline into the intake passage 2 at a predetermined timing according to the rotational position of the rotor 12 when the fuel used is gasoline.

  FIG. 2 schematically shows the configuration of an intake system, an exhaust system, and a fuel supply system for the rotary engine 1. In FIG. 2, 31 is a hydrogen tank as a gaseous fuel tank that stores hydrogen therein, and 41 is a gasoline tank that contains gasoline therein. The hydrogen tank 31 is provided with a main valve 31a that is opened and closed by a main valve actuator 61 (see FIG. 1). The main valve 31a and each of the hydrogen injectors 4 are connected to a gaseous fuel supply path. They are connected by a hydrogen supply pipe 32 constituting the same. The gasoline tank 41 and the gasoline injectors 5 are connected by a gasoline supply pipe 42. In the present embodiment, the pressure in the hydrogen tank 31 is set to 36 MPa.

  The main valve 31a of the hydrogen tank 31 is opened when the fuel used is hydrogen, and is closed when the fuel used is gasoline. When the main valve 31a is closed, the hydrogen supply from the hydrogen tank 31 to the hydrogen supply pipe 32 is not performed. When the main valve 31a is opened, the hydrogen supply from the hydrogen tank 31 to the hydrogen supply pipe 32 is not performed. Made.

  A shutoff valve 33 that is opened and closed by a shutoff valve actuator 62 (see FIG. 1) is disposed in the vicinity of the injector 4 in the hydrogen supply pipe 32. This shutoff valve 33 is also the same as the main valve 31a. It is opened when the fuel used is hydrogen, and closed when the fuel used is gasoline. When the shut-off valve 33 is closed, hydrogen is not supplied from the hydrogen supply pipe 32 to the injector 4, and when the shut-off valve 33 is opened, hydrogen is supplied from the hydrogen supply pipe 32 to the injector 4. . The main valve 31a and the shutoff valve 33 are for preventing hydrogen from leaking from the hydrogen supply pipe 32 when the fuel used is gasoline.

  Further, a regulator (pressure reducing valve) 34 is provided in the vicinity of the main valve 31a in the hydrogen supply pipe 32, and hydrogen is reduced in pressure by the regulator 34 (in this embodiment, 0). The pressure is reduced to 6 MPa), and is supplied to the injector 4 through the hydrogen supply pipe 32.

  As shown in FIG. 2 (not shown in FIG. 1), the portion of the intake passage 2 that is upstream of the branching portion and the portion of the exhaust passage 3 that is downstream of the joining portion are EGR. A part of the exhaust gas from the engine 1 is recirculated to the intake passage 2 through the EGR passage 45. An EGR valve 46 is disposed in the EGR passage 45. The opening degree of the EGR valve 46 is adjusted by the EGR valve actuator 47, and the exhaust gas recirculation amount recirculated to the intake passage 2 is determined by the opening degree of the EGR valve 46. The EGR passage 45, the EGR valve 46, and the EGR valve actuator 47 constitute exhaust recirculation means for recirculating the exhaust of the engine 1 to the intake passage 2 of the engine 1. The opening degree of the EGR valve 46 is detected by an EGR valve opening degree sensor 54 (in this embodiment, which is also used as the EGR valve actuator 47).

  The PCM 6 includes at least a vehicle as shown in FIG. 1 in addition to signals necessary for controlling the operation of the ignition plugs 14, the actuators 21 of the throttle valves 22, and the injectors 4 and 5 for hydrogen and gasoline injection. The vehicle speed sensor 51 for detecting the vehicle speed, the accelerator opening sensor 52 for detecting the accelerator pedal depression amount (accelerator opening) of the vehicle occupant, and the output signals of the EGR valve opening sensor 54 are input. It has become.

  In addition to the operation control of the ignition plugs 14, the actuators 21 of the throttle valves 22 and the injectors 4 and 5 for hydrogen and gasoline injection, the PCM 6 includes the vehicle speed sensor 51, the accelerator opening as described in detail later. Based on the output signals of the output signals of the degree sensor 52 and the EGR valve opening sensor 54, the main valve actuator 61, the shutoff valve actuator 62, etc. are controlled to switch the fuel used, and the EGR valve 46 The EGR valve actuator 47 is controlled so that the opening becomes an opening corresponding to the required fuel and the required torque of the occupant to the engine 1 (an opening corresponding to an exhaust gas recirculation rate described later).

  Specifically, the PCM 6 switches the fuel to be used in accordance with the required torque for the occupant engine 1 as a value related to the driving state of the vehicle (driving state-related value). That is, based on the vehicle speed detected by the vehicle speed sensor 51 and the accelerator opening detected by the accelerator opening sensor 52, the required torque is detected from the map of FIG. 3 (hereinafter referred to as map A) stored in the PCM 6. To do. Thus, the vehicle speed sensor 51, the accelerator opening sensor 52, and the PCM 6 constitute driving state related value detecting means for detecting a value related to the driving state of the vehicle.

  In the map A, a line (solid line and two-dot chain line) in which the accelerator opening decreases as the vehicle speed increases is an equal required torque line, and one of the equal required torque lines (solid line) is set in advance. This is a switching threshold (predetermined value). When the detected required torque is larger than the switching threshold value (when the coordinate point of the vehicle speed and the accelerator opening is in the upper right region with respect to the switching threshold value), the PCM 6 When the required torque is equal to or less than the switching threshold (when the coordinate point of the vehicle speed and the accelerator opening is in the lower left area with respect to the switching threshold including the switching threshold), the fuel used is hydrogen. . Therefore, when the detected required torque becomes a value larger than the switching threshold value from the value below the switching threshold value, the PCM 6 executes the switching of the fuel used from hydrogen to gasoline, but is larger than the switching threshold value. When the value becomes equal to or less than the switching threshold value, the fuel to be used is switched from gasoline to hydrogen. However, the PCM 6 limits the execution of the next use fuel switching until a predetermined time (for example, 1 minute) elapses from the execution of the use fuel switching. In the present embodiment, the restriction is performed by prohibiting the execution of the next fuel change. Thus, the PCM 6 constitutes a used fuel switching means for switching the used fuel according to the operating state related value detected by the operating state related value detecting means, and executes the next switching of the used fuel. Limiting means for limiting is configured.

  When the fuel is switched, if the gasoline is injected into the intake passage 2 by the gasoline injection injector 5, the gasoline injection is stopped, and then the main valve 31a and the shutoff valve 33 are stopped. Is opened, and when hydrogen is injected into the cylinder 11 by the injector 4 for hydrogen injection and hydrogen is injected by the injector 4 for hydrogen injection, after the hydrogen injection is stopped, the main valve 31a And the shutoff valve 33 is closed, and gasoline is injected by the injector 5 for gasoline injection. The main valve 31a and the shutoff valve 33 correspond to control valves controlled by the PCM 6 as the used fuel switching means.

  Here, as shown in FIG. 4, when the fuel used is gasoline (when the required torque is larger than the switching threshold value), the exhaust gas recirculation rate (recirculation for the total intake air amount including the fresh air amount and the recirculated exhaust amount). The ratio of displacement (hereinafter referred to as the EGR rate) is gradually increased from 3% to 0% as the required torque increases. On the other hand, when the fuel used is hydrogen (when the required torque is less than or equal to the switching threshold), the EGR rate is set to 30%. Thus, the EGR rate when the fuel used is hydrogen is higher than when the fuel used is gasoline. This is because when the fuel used is hydrogen, hydrogen pre-ignition is likely to occur, which is suppressed.

  The PCM 6 controls the EGR valve actuator 47 so that the EGR rate set as described above is obtained. That is, the EGR valve actuator 47 is controlled based on the output signal of the EGR valve opening sensor 54 so that the opening of the EGR valve 46 becomes a value corresponding to the EGR rate of FIG.

  Next, a specific processing operation regarding the switching of the fuel used in the PCM 6 will be described with reference to FIG.

  First, in the first step S1, output values (vehicle speed and accelerator opening) of the vehicle speed sensor 51 and the accelerator opening sensor 52 are inputted, and in the next step S2, the vehicle speed and accelerator opening and the map A are detected. It is determined whether or not the requested torque is equal to or less than the switching threshold of the map A. When the determination in step S2 is YES, the process proceeds to step S3. When the determination in step S2 is NO, the process proceeds to step S6.

  In step S3, which proceeds when the determination in step S2 is YES, it is determined whether or not the currently used fuel is hydrogen. When the determination in step S3 is YES, the process proceeds to step S4 and hydrogen is supplied. On the other hand, if the determination is NO in step S3, the process proceeds to step S5, the fuel is switched from gasoline to hydrogen, and then the process proceeds to step S9.

  On the other hand, in step S6 that proceeds when the determination in step S2 is NO, it is determined whether or not the currently used fuel is gasoline. When the determination in step S6 is YES, the process proceeds to step S7. On the other hand, if the determination in step S6 is NO, the routine proceeds to step S8, where the fuel is switched from hydrogen to gasoline, and then the process proceeds to step S9.

  In step S9 following step S5 and step S8, switching of the next used fuel is prohibited, and in next step S10, it is determined whether or not a predetermined time has elapsed since the switching was prohibited. When the determination in step S10 is NO, the process in step S10 is repeated. When the determination in step S10 is YES, the process proceeds to step S11, the switching prohibition is canceled, and the process returns.

  When the required torque is changed from a value below the switching threshold to a value larger than the switching threshold by the processing operation of the PCM 6, the fuel used is switched from hydrogen to gasoline, and from the value larger than the switching threshold to below the switching threshold. When it reaches the value, it is switched from gasoline to hydrogen. Then, until the predetermined time elapses after the used fuel is switched, the next used fuel is not switched regardless of the value of the required torque.

  Therefore, in this embodiment, since the execution of the next change of the used fuel is prohibited until the predetermined time elapses from the execution of the change of the used fuel, the change of the used fuel does not frequently occur. Torque shock due to switching does not occur frequently. As a result, even if the EGR rate when the fuel used is hydrogen is higher than when the fuel used is gasoline, the passenger is less likely to feel discomfort due to torque shock. That is, as can be seen from the EGR rate in FIG. 4, when the fuel used is switched from gasoline to hydrogen, the amount of change in the opening of the EGR valve 46 is very large. Therefore, when the fuel used is switched from gasoline to hydrogen, EGR The response delay of the valve actuator 47 occurs, and the EGR rate does not increase immediately. During this time, hydrogen pre-ignition is likely to occur and a large torque shock is likely to occur. Further, when switching from gasoline to hydrogen, response delays of the main valve actuator 61 and the shutoff valve actuator 62 occur, and a large torque shock is likely to occur due to this response delay. In addition to these, if the fuel to be used is frequently switched, the occupant tends to feel a considerable sense of incongruity. However, in the present embodiment, the switching of the used fuel does not frequently occur as described above, and in particular, until the predetermined time elapses from the execution of the switching of the used fuel from hydrogen to gasoline, By prohibiting switching to, it is possible to prevent the passenger from feeling as uncomfortable as possible from the torque shock.

(Embodiment 2)
In the present embodiment, the execution of the switching of the fuel to be used from the next gasoline to hydrogen is limited only until a predetermined time has elapsed since the switching of the fuel to be used from hydrogen to gasoline. The configuration of the rotary engine 1 and the intake system, exhaust system, and fuel supply system for the engine 1 are the same as those in the first embodiment.

  In other words, in the present embodiment, the PCM 6 reduces the switching threshold value until the predetermined time has elapsed from the execution of switching of the fuel used from hydrogen to gasoline, so that the fuel used from the next gasoline to hydrogen is reduced. The execution of switching is limited so that it is difficult to execute switching. Specifically, the map A in the first embodiment is changed to the map shown in FIG. 6 (hereinafter referred to as map B) until a predetermined time elapses after execution of switching of the fuel used from hydrogen to gasoline. In this map B, the switching threshold value is smaller than that in map A. For this reason, it is difficult to switch from gasoline to hydrogen until a predetermined time elapses after the fuel used switches from hydrogen to gasoline.

  On the other hand, when switching from gasoline to hydrogen, the execution of switching from the next hydrogen to gasoline is not restricted. That is, map A is continued without changing to map B. Therefore, the PCM 6 limits the execution of the next fuel switching from gasoline to hydrogen only until a predetermined time has elapsed since the switching of the fuel used from hydrogen to gasoline.

  A specific processing operation in the PCM 6 will be described with reference to FIGS. Steps S21 to S28 are the same as steps S1 to S8 in the flowchart of FIG. 5 in the first embodiment, and the processing operations after steps S25 and S28 are different from those in the first embodiment. The operation will be described.

  That is, after step S25, the process returns. After step S28, the process proceeds to step S29, the fuel switching map is changed to map B, and a timer is set in the next step S30.

  In the next step S31, the output values (vehicle speed and accelerator opening) of the vehicle speed sensor 51 and the accelerator opening sensor 52 are inputted, and in the next step S32, the vehicle speed and the accelerator opening and the request detected from the map B. It is determined whether the torque is equal to or less than the switching threshold of the map B.

  When the determination in step S33 is YES, the process proceeds to step S33, where fuel switching from gasoline to hydrogen is executed. In the next step S34, the fuel switching map is returned to map A, and then the process returns.

  On the other hand, when the determination in step S33 is NO, the process proceeds to step S35, and gasoline is continuously used, and the process proceeds to step S36. Then, in this step S36, it is determined whether or not a predetermined time has elapsed from the setting of the timer. If the determination in step S36 is NO, the process returns to step S31, while the determination in step S36 is YES. In some cases, the process proceeds to step S37 to return the fuel switching map to the map A, and then returns.

  When the required torque becomes a value larger than the switching threshold value from the value below the switching threshold of the map A by the processing operation of the PCM 6, the fuel used is switched from hydrogen to gasoline, and a value larger than the switching threshold value of the map A When the value becomes less than the switching threshold value, the gasoline is switched to hydrogen.

  When the fuel used is switched from gasoline to hydrogen, switching from the next hydrogen to gasoline is not limited, and even if within a predetermined time from the switching, the required torque is reduced from a value below the switching threshold of map A. When the value becomes larger than the switching threshold, the fuel is switched from hydrogen to gasoline.

  On the other hand, when the fuel used is switched from hydrogen to gasoline, switching from the next gasoline to hydrogen is restricted for a predetermined time from the switching, and the required torque is greater than the switching threshold in Map B. If it does not become the following value, it will not switch from gasoline to hydrogen. Thereby, since the switching threshold value of map B is smaller than that of map A, switching from gasoline to hydrogen is less likely to occur. When a predetermined time elapses from the switching, the map returns to the map A, so that the switching limitation is released.

  In the present embodiment, as in the first embodiment, when switching from gasoline to hydrogen, hydrogen pre-ignition is likely to occur and response delays of the main valve actuator 61 and the shut-off valve actuator 62 occur. Is likely to occur. In addition, if the used fuel is frequently switched, the occupant tends to feel a great sense of incongruity. However, in the present embodiment, the execution of the switching of the fuel to be used from gasoline to hydrogen is limited until the predetermined time has elapsed since the switching of the fuel to be used from hydrogen to gasoline. In the same manner as described above, it is possible to prevent the passenger from feeling as uncomfortable as possible from the torque shock.

  On the other hand, when the gasoline is switched to hydrogen, execution of switching of the next fuel to be used from hydrogen to gasoline is not limited. That is, the reason for switching from hydrogen to gasoline is that the occupant is requesting high torque, so that it is possible to quickly respond to the high torque request by not limiting this switching. Moreover, when switching from hydrogen to gasoline, the torque shock is relatively small and does not pose a major problem.

  Therefore, by limiting the execution of the switching of the fuel used from gasoline to hydrogen only until the predetermined time has elapsed since the switching of the fuel used from hydrogen to gasoline, the occupant's demand for high torque can be met. Can respond quickly and prevent the passengers from feeling as uncomfortable as possible from the torque shock.

  In the second embodiment, the execution of the switching of the used fuel from gasoline to hydrogen is limited only until the predetermined time has elapsed since the switching of the used fuel from hydrogen to gasoline. Similarly, during the period from the execution of switching of the fuel used for gasoline to hydrogen until a predetermined time elapses, the map B is similarly changed to limit the execution of the switching of the fuel used for the next hydrogen to gasoline. May be.

  Further, it may be limited by prohibiting the execution of the switching of the fuel to be used from gasoline to hydrogen only until a predetermined time has elapsed since the switching of the fuel to be used from hydrogen to gasoline.

  Furthermore, in Embodiments 1 and 2, the occupant's required torque for the engine 1 is detected as a value related to the driving state of the vehicle, but it may be, for example, an engine speed or an engine load.

  Furthermore, in the first and second embodiments, the present invention is applied to the rotary engine 1 that can switch between hydrogen and gasoline as the fuel to be used, but dual fuel that can switch between gaseous fuel such as natural gas and gasoline. The present invention can also be applied to an engine (not limited to a rotary engine).

  INDUSTRIAL APPLICABILITY The present invention is useful for a fuel switching control device for a dual fuel engine that can switch between gaseous fuel and gasoline as the fuel used.

It is a schematic block diagram which shows the fuel switching control apparatus of the dual fuel engine which concerns on Embodiment 1 of this invention. It is a schematic block diagram which shows the intake system with respect to the said engine, an exhaust system, and a fuel supply system. It is a figure which shows the map A for fuel switching. It is a figure which shows the relationship between a request torque and an exhaust gas recirculation rate (EGR rate). It is a flowchart which shows the processing operation regarding the switching of the fuel used in a powertrain control module. It is a figure which shows the map B which made the switching threshold value small with respect to the map A. 10 is a flowchart showing a first half of a processing operation relating to switching of fuel used in the powertrain control module in the second embodiment. It is a flowchart which shows the latter half part of the processing operation regarding the switching of the said use fuel.

1 Rotary engine (dual fuel engine)
4 Injector for hydrogen injection (gaseous fuel supply means)
6 Powertrain control module
(Operating state related value detecting means) (Fuel used switching means) (Limiting means)
31 Hydrogen tank (gaseous fuel tank)
31a Main valve (control valve)
32 Hydrogen supply pipe (gaseous fuel supply path)
33 Shut-off valve (control valve)
45 EGR passage (exhaust gas recirculation means)
46 EGR valve (exhaust gas recirculation means)
47 EGR valve actuator (exhaust gas recirculation means)
51 Vehicle speed sensor (Driving condition related value detection means)
52 Accelerator opening sensor (operating state related value detection means)

Claims (5)

A fuel switching control device for a dual fuel engine mounted on a vehicle and capable of switching between gaseous fuel and gasoline as fuel used,
Driving state related value detecting means for detecting a value related to the driving state of the vehicle;
Use fuel switching means for switching the use fuel according to the operation state related value detected by the operation state related value detection means;
Limiting means for restricting execution of the switching of the next used fuel by the used fuel switching means until a predetermined time elapses from the execution of the switching of the used fuel by the used fuel switching means ,
The dual fuel engine characterized in that the restriction means is configured to immediately release the restriction on the execution of the switching when a predetermined time has elapsed since the execution of the switching of the used fuel by the use fuel switching means. Fuel switching control device. The fuel switching control device for a dual fuel engine according to claim 1,
A gaseous fuel tank for storing the gaseous fuel;
A gaseous fuel supply path connecting the gaseous fuel tank and gaseous fuel supply means for supplying the gaseous fuel to the combustion chamber of the engine;
A control valve provided in the gaseous fuel supply path and controlled by the used fuel switching means;
When the operating state related value detected by the operating state related value detecting unit changes from a value less than or equal to a predetermined value to a value greater than the predetermined value, the used fuel switching unit is configured to use fuel from gaseous fuel to gasoline. On the other hand, when the value greater than the predetermined value becomes equal to or smaller than the predetermined value, the fuel used is switched from gasoline to gaseous fuel.
The limiting means is a fuel used from the next gasoline to the gaseous fuel by the used fuel switching means only until a predetermined time has elapsed since the execution of the switching of the used fuel from the gaseous fuel to the gasoline by the used fuel switching means. The switching of the used fuel from the gasoline to the gaseous fuel by the used fuel switching means is executed and the switching of the used fuel from the next gaseous fuel to the gasoline is performed by the used fuel switching means. A fuel switching control device for a dual fuel engine, characterized in that it is configured so as not to limit the fuel consumption. The fuel switching control device for a dual fuel engine according to claim 2,
The limiting means reduces the predetermined value until a predetermined time elapses after execution of the switching of the used fuel from the gaseous fuel to the gasoline by the used fuel switching means. A fuel switching control device for a dual fuel engine, characterized in that execution of switching of the fuel used from gasoline to gaseous fuel is limited. The fuel switching control device for a dual fuel engine according to claim 1 or 2,
The fuel switching control device for a dual fuel engine, wherein the limiting means is configured to limit the execution of the switching of the next used fuel by the used fuel switching means. In the fuel switching control device for a dual fuel engine according to any one of claims 1 to 4,
The gaseous fuel is hydrogen;
An exhaust gas recirculation means for recirculating the exhaust gas of the engine in the intake passage of the engine;
The dual-fuel engine fuel switching control device according to claim 1, wherein the exhaust gas recirculation means is configured to make an exhaust gas recirculation rate higher when the fuel used is hydrogen than when the fuel used is gasoline.

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