JP2019183687A - Engine system - Google Patents

Abstract

To prevent the operation sound of a purge pump from being audible as uncomfortable abnormal sound at the time of the temporary stop of an engine.SOLUTION: An engine system includes an engine 1 constructed in a temporarily stoppable manner, an intake passage 3, a fuel tank 5, an evaporated fuel treatment device 30 for trapping evaporated fuel generated in a fuel tank 5 in a canister 21 once, and purging it into the intake passage 3 via a purge passage 23 in which a purge valve 24 and a purge pump 25 are provided, so as to be treated, and an electronic control device (ECU) for controlling the engine 1, the purge valve 24 and the purge pump 25. When receiving a temporary stop request for the engine 1 during operating the engine 1 as well as the purge pump 25, the ECU 50 controls the engine 1 to gradually change the rotating speed of the purge pump 25 to be lower since receiving the request, and stop the engine 1 when the operation sound of the purge pump 25 is as smaller as that a vehicle crew cannot hear.SELECTED DRAWING: Figure 1

Description

  The technology disclosed in this specification relates to an engine system including an engine, a fuel tank that stores fuel supplied to the engine, and an evaporated fuel processing device that processes evaporated fuel generated in the fuel tank.

  Conventionally, as this type of technology, for example, an “evaporated fuel processing apparatus” described in Patent Document 1 below is known. The apparatus includes a canister that collects evaporated fuel (vapor) generated in a fuel tank, a purge passage that guides the vapor collected in the canister to an intake passage of an engine, a purge valve that opens and closes the purge passage, and a purge passage And a purge pump that pumps the vapor collected in the canister to the intake passage, and an electronic control unit (ECU) that controls the purge valve and the purge pump. This device may be provided in an engine configured to be capable of temporary stop (for example, idle stop or intermittent stop). For example, in a hybrid vehicle or an idle stop vehicle, the engine is temporarily stopped in response to a temporary stop request such as an intermittent stop request or an idle stop request.

JP 2017-670008 A

  However, in the case of the engine as described above, if a request for a temporary stop to the engine is made when the purge pump is operating at a high speed, the purge pump continues to operate for a while even if the engine stops thereafter. In some cases, the operating noise may be heard as an unpleasant noise for the vehicle occupant.

  The disclosed technology has been made in view of the above circumstances, and the purpose thereof is to prevent the operation sound of the purge pump from being heard as an unpleasant noise when the engine is temporarily stopped. It is to provide an engine system.

  In order to achieve the above object, the technology according to claim 1 is an engine system mounted on a vehicle, wherein the engine is configured to be temporarily stopped, an intake passage for introducing intake air into the engine, A fuel tank for storing the fuel supplied to the engine and the evaporated fuel generated in the fuel tank are once collected in a canister and purged to the intake passage through a purge passage provided with a purge valve and a purge pump. In an engine system comprising an evaporative fuel processing device to be processed and a control means for controlling the engine, a purge valve and a purge pump, the control means temporarily stops the engine during operation of the engine and during operation of the purge pump. When a request is received, the purge pump rotation speed is gradually decreased after the request is received, and the purge pump operation sound is Engine when it is small enough to not hear the occupant of both is to purpose to control the engine to stop.

  In the configuration of the above technique, the engine emits an operating noise during operation of the engine, and when the engine stops, the engine does not emit an operating noise. Similarly, during operation of the purge pump, the purge pump emits an operating noise, and when the purge pump stops, the purge pump does not emit an operating noise. According to the above configuration, during the operation of the engine (when the engine makes an operating noise) and during the operation of the purge pump (when the purge pump makes an operating noise), the engine is requested to pause (for example, an idle stop request or intermittent When the stop request is received, the engine speed stops when the purge pump speed gradually decreases and the operation sound of the purge pump becomes so low that the vehicle occupant cannot hear it. So that the engine is controlled. Accordingly, when the operation sound of the purge pump is loud enough to be heard by the vehicle occupant, the operation sound is generated without stopping the engine, so that the operation sound of the purge pump is drowned out by the operation sound of the engine.

  In order to achieve the above object, according to a second aspect of the present invention, in the technique according to the first aspect, the number of revolutions of the purge pump is set to a first predetermined value to such an extent that the operating noise of the purge pump cannot be heard by a vehicle occupant. The purge pump rotational speed at which the operation sound of the purge pump can be heard by the vehicle occupant is defined as the second predetermined value, and the control means starts until the purge pump rotational speed starts decreasing until the second predetermined value. When the engine speed decreases, the engine speed starts to decrease. When the purge pump speed reaches the first predetermined value, the engine is stopped, and the purge pump is stopped after the first predetermined value is maintained for a predetermined time. The purpose is to make it.

  According to the configuration of the above technology, in addition to the operation of the technology described in claim 1, after the rotation speed of the purge pump starts to decrease, the first predetermined value (the rotation at which the operating noise of the purge pump cannot be heard by the vehicle occupant). The engine speed starts to decrease when the engine speed decreases to a second predetermined value that is higher than the second predetermined value (the speed at which the operation sound of the purge pump can be heard by the vehicle occupant). At higher conditions, the engine continues to run. Further, when the number of revolutions of the purge pump reaches the first predetermined value, the engine is stopped and the purge pump is stopped after the first predetermined value is held for a predetermined time. Therefore, even if the engine is stopped and the engine is restarted shortly thereafter, the purge pump is maintained at the first predetermined value, so that the purge pump can be easily restarted.

  According to the first aspect of the present invention, when the engine is temporarily stopped, the operation sound of the purge pump can be prevented from being heard as an unpleasant noise.

  According to the technique described in claim 2, in addition to the effect of the technique described in claim 1, when the engine is restarted in the middle of the temporary stop, the purge pump can be promptly restarted. The power required for restarting can be reduced, and the vapor purge flow rate recovery can be accelerated.

1 is a schematic diagram showing an engine system including an evaporated fuel processing device mounted on a vehicle according to one embodiment. The flowchart which shows the processing content of purge pump stop control concerning one Embodiment. The time chart which shows the behavior of the various parameters regarding purge pump control concerning one Embodiment. The time chart which shows the behavior of the various parameters (proportional) regarding purge pump control concerning one Embodiment.

  Hereinafter, an embodiment embodying an engine system will be described in detail with reference to the drawings.

[About engine system overview]
FIG. 1 schematically shows an engine system including an evaporative fuel processing device 30 mounted on a vehicle 60. As is well known, the vehicle 60 includes a driver seat, a passenger seat, and the like, and is configured to be able to carry a plurality of passengers. The engine 1 includes an intake passage 3 for allowing air or the like to be sucked into the combustion chamber 2 and an exhaust passage 4 for discharging exhaust gas from the combustion chamber 2. The fuel stored in the fuel tank 5 is supplied to the combustion chamber 2. That is, the fuel in the fuel tank 5 is discharged to the fuel passage 7 by the fuel pump 6 built in the tank 5 and is pumped to the injector 8 provided in the intake port of the engine 1. The pumped fuel is injected from the injector 8 and introduced into the combustion chamber 2 together with the air flowing through the intake passage 3 to form a combustible air-fuel mixture, which is used for combustion. The engine 1 is provided with an ignition device 9 for igniting a combustible air-fuel mixture.

  An air cleaner 10, a throttle device 11, and a surge tank 12 are provided in the intake passage 3 from the inlet side to the engine 1. The throttle device 11 includes a throttle valve 11 a and is opened and closed to adjust the intake flow rate flowing through the intake passage 3. The opening and closing of the throttle valve 11a is linked to the operation of an accelerator pedal (not shown) by the driver. The surge tank 12 smoothes the intake pulsation in the intake passage 3.

[Configuration of Evaporative Fuel Treatment System]
In FIG. 1, the evaporated fuel processing device 30 of this embodiment is configured to process the evaporated fuel (vapor) generated in the fuel tank 5 without releasing it into the atmosphere. This apparatus includes a canister 21 for collecting vapor generated in the fuel tank 5, a vapor passage 22 for introducing vapor from the fuel tank 5 to the canister 21, and an intake passage for the vapor collected in the canister 21. 3, a purge valve 24 provided in the purge passage 23 for adjusting the vapor purge flow rate, and a canister 21 and a purge valve for pressure-feeding vapor from the canister 21 to the purge passage 23. 24 and a purge pump 25 provided between the two.

  The canister 21 contains an adsorbent such as activated carbon. The canister 21 includes an air inlet 21a for introducing air, an inlet 21b for introducing vapor, and a lead-out port 21c for deriving vapor. The internal space of the canister 21 communicates with the atmosphere. That is, the tip of the atmospheric passage 26 extending from the atmospheric port 21 a communicates with the inlet of the fuel tank 5 a of the fuel tank 5. The atmospheric passage 26 is provided with a filter 27 for collecting dust and the like in the air. The tip of the vapor passage 22 extending from the introduction port 21 b of the canister 21 communicates with the inside of the fuel tank 5. The tip of the purge passage 23 provided between the canister 21 and the intake passage 3 communicates with the intake passage 3 between the throttle device 11 and the surge tank 12.

  In this embodiment, the purge valve 24 is composed of a motor-operated valve (VSV), and is configured to have a variable opening in order to adjust the vapor flow rate. The purge pump 25 is configured to have a variable discharge amount in order to pressure-feed vapor from the canister 21 to the purge passage 23. As the purge pump 25, for example, a turbine pump can be employed.

  The evaporative fuel processing device 30 configured as described above introduces vapor generated in the fuel tank 5 into the canister 21 through the vapor passage 22 and temporarily collects the vapor in the canister 21. When the engine 1 is in operation, the throttle device 11 (throttle valve 11a) is opened, the purge valve 24 is opened, and the purge pump 25 is activated. As a result, the vapor collected in the canister 21 is purged from the canister 21 to the intake passage 3 via the purge passage 23.

  In this embodiment, the vapor passage 22 is provided with a shutoff valve 28 for controlling the gas flow between the fuel tank 5 and the canister 21. The shutoff valve 28 is configured to open when the internal pressure of the fuel tank 5 becomes a positive pressure equal to or higher than a predetermined value, and is closed by a negative pressure when the vapor collected in the canister 21 is purged to the intake passage 3. The

[Electric configuration of engine system]
In this embodiment, various sensors 41 to 46 are provided to detect the operating state of the engine 1. The air flow meter 41 provided near the air cleaner 10 detects the amount of air sucked into the intake passage 3 as the amount of intake air, and outputs an electric signal corresponding to the detected value. A throttle sensor 42 provided in the throttle device 11 detects the opening of the throttle valve 11a as a throttle opening, and outputs an electric signal corresponding to the detected value. The intake pressure sensor 43 provided in the surge tank 12 detects the pressure in the surge tank 12 as the intake pressure, and outputs an electrical signal corresponding to the detected value. The water temperature sensor 44 provided in the engine 1 detects the temperature of the cooling water flowing inside the engine 1 as the cooling water temperature, and outputs an electrical signal corresponding to the detected value. A rotation speed sensor 45 provided in the engine 1 detects a rotation angular velocity of a crankshaft (not shown) of the engine 1 as the engine rotation speed NE, and outputs an electric signal corresponding to the detected value. The oxygen sensor 46 provided in the exhaust passage 4 detects the oxygen concentration in the exhaust gas and outputs an electrical signal corresponding to the detected value.

  In this embodiment, an electronic control unit (ECU) 50 that controls various controls inputs various signals output from various sensors 41 to 46. The ECU 50 controls the injector 8, the ignition device 9, the purge valve 24, and the purge pump 25 based on these input signals, thereby controlling fuel injection control, ignition timing control, purge control, idle stop control, intermittent stop control, and purge stop control. Is supposed to run.

  Here, the fuel injection control is to control the fuel injection amount and the fuel injection timing by controlling the injector 8 in accordance with the operating state of the engine 1. The ignition timing control is to control the ignition timing of the combustible mixture by controlling the ignition device 9 according to the operating state of the engine 1. The purge control is to control the purge flow rate of the vapor from the canister 21 to the intake passage 3 by controlling the purge valve 24 and the purge pump 25 according to the operating state of the engine 1. The idle stop control is to forcibly temporarily stop the engine 1 by stopping the injector 8 and the ignition device 9 in response to an idle stop request for the engine 1. The intermittent stop control is to forcibly temporarily stop the engine 1 by stopping the injector 8 and the ignition device 9 in response to an intermittent stop request to the engine 1. Further, the purge stop control is to forcibly stop the purge of the vapor by controlling the purge pump 25 to stop in response to an idle stop request or an intermittent stop request to the engine 1.

  In this embodiment, the ECU 50 corresponds to an example of a control unit in the disclosed technology. The ECU 50 has a known configuration including a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a backup RAM, and the like. The ROM stores in advance predetermined control programs related to the various controls described above. The ECU (CPU) 50 executes the various controls described above according to these control programs.

  In this embodiment, the engine 1 is configured to be capable of idling stop and intermittent stop. In this embodiment, the fuel injection control, the ignition timing control, the purge control, the idle stop control, and the intermittent stop control are well-known contents, and only the purge stop control will be described in detail below.

[Purge stop control]
Next, purge stop control will be described. FIG. 2 is a flowchart showing the control contents. The ECU 50 periodically executes this routine every predetermined time.

  When the process proceeds to this routine, in step 100, the ECU 50 determines whether there is an idle stop request or an intermittent stop request for the engine 1. If this determination result is affirmative, the ECU 50 proceeds to step 110, and if this determination result is negative, the ECU 50 temporarily terminates the process.

  In step 110, the ECU 50 closes the purge valve 24. Next, in step 120, the ECU 50 controls the purge pump 25 so as to gradually decrease the rotational speed (pump rotational speed) NP of the purge pump 25 toward a first predetermined value NP1 (for example, 10000 rpm). When the pump speed NP reaches the first predetermined value NP1, the ECU 50 temporarily holds the predetermined value NP1. The reason why the pump rotational speed NP is once held at the first predetermined value NP1 is to accelerate the restart of the purge pump 25 when the engine 1 is restarted. Here, the first predetermined value NP1 is a value such that the operating sound of the purge pump 25 is not noticed by the passenger.

  Next, at step 130, the ECU 50 determines whether or not the actual pump speed NP is equal to or less than a second predetermined value NP2 (for example, 20000 rpm). The ECU 50 can obtain a signal corresponding to the pump rotational speed NP from the motor constituting the purge pump 25. The ECU 50 proceeds to step 140 if the determination result is affirmative, and returns the process to step 120 if the determination result is negative.

  In step 140, the ECU 50 turns on the engine stop request. That is, the ECU 50 stops the fuel supply from the injector 8 to the engine 1 and stops the ignition operation of the ignition device 9. As a result, the rotational speed of the engine 1 begins to decrease.

  Next, in step 150, the ECU 50 waits for a predetermined time (for example, “1 second”) to elapse after the engine speed NE becomes “0”, and proceeds to step 160. The ECU 50 can make this determination based on the detection value of the rotation speed sensor 45.

  In step 160, the ECU 50 stops the purge pump 25 and temporarily terminates the process. That is, the ECU 50 cuts off the power supply to the purge pump 25.

  According to the above control, when the engine 50 is in operation and the purge pump 25 is in operation, the ECU 50 receives the request for temporary stop (for example, idle stop request or intermittent stop request). The engine 1 is stopped so that the engine 1 is stopped when the rotation speed of the purge pump 25 (pump rotation speed NP) is gradually decreased and the operating noise of the purge pump 25 becomes so small that it cannot be heard by the passenger of the vehicle 60. 1 is controlled. Further, the ECU 50 reduces the rotational speed of the engine 1 when the pump rotational speed NP starts to decrease to a second predetermined value NP2 (the rotational speed at which the operating sound of the purge pump 25 can be heard by the vehicle 60 occupant). The engine 1 is stopped when the rotational speed of the purge pump 25 reaches a first predetermined value NP1 (the rotational speed at which the operating sound of the purge pump 25 cannot be heard by the occupant of the vehicle 60). The purge pump 25 is stopped after holding the value NP1 for a predetermined time.

  Here, FIG. 3 shows an example of the behavior of various parameters associated with the above control in a time chart. 3A shows an idle stop request, FIG. 3B shows a pump speed NP, FIG. 3C shows an engine stop request, and FIG. 3D shows an engine speed NE. FIG. 4 is a time chart showing an example of the behavior of various parameters associated with the conventional control for comparison. 4, (a) shows an idle stop request, (b) shows a pump speed NP, (c) shows an engine stop request, and (d) shows an engine speed NE. In FIG. 3B and FIG. 4B, the thick line indicates the actual rotational speed, and the thick broken line indicates the target rotational speed.

  In FIG. 3, when an idle stop request is input at time t1 (from “0” to “1”), the pump rotational speed NP (both the actual rotational speed and the target rotational speed) starts to decrease. Thereafter, when the pump rotational speed NP (both the actual rotational speed and the target rotational speed) decreases to the second predetermined value NP2 at time t2, an engine stop request is input (from “0” to “1”), The engine speed NE starts to decrease. Thereafter, when the pump rotational speed NP (both the actual rotational speed and the target rotational speed) decreases to the first predetermined value NP1 at time t3, the engine rotational speed NE also becomes “0”, and then the pump rotational speed NP ( Both the actual rotational speed and the target rotational speed) are held at the first predetermined value NP1 until time t4 (predetermined time). At time t4, the pump rotational speed NP (both the actual rotational speed and the target rotational speed) becomes “0”, that is, the purge pump 25 is stopped. Therefore, as soon as an idle stop request is received, the purge pump 25 gradually decreases its pump speed NP, but the engine 1 is stopped because the pump speed NP is relatively low and the operation sound of the purge pump 25 is relatively low. When the first predetermined value NP1 is reached and the operation sound of the purge pump 25 is relatively loud, the operation sound overlaps with the operation sound of the engine 1.

  On the other hand, in the conventional control, when an idle stop request is made at time t1 in FIG. 4 (from “0” to “1”), the pump rotation speed NP (target rotation speed) becomes “0”, and the pump rotation The number NP (actual rotational speed) starts to decrease. At the same time, an engine stop request is input (from “0” to “1”), and the engine speed NE begins to decrease. Thereafter, at time t2, the engine rotational speed NE becomes “0” (the engine 1 stops), but the pump rotational speed NP (actual rotational speed) is decreasing at a relatively high rotational speed. Therefore, from the time t2 to the time t3 when the pump rotation speed NP (actual rotation speed) becomes “0”, only the purge pump continues to operate for a while after the engine is stopped. The operating sound may be heard as an unpleasant noise.

[Operation and effect of evaporative fuel treatment system]
According to the engine system in this embodiment described above, the engine 1 emits an operating noise while the engine 1 is in operation, and the engine 1 does not emit an operating noise when the engine 1 stops. Similarly, during operation of the purge pump 25, the purge pump 25 emits an operating noise. When the purge pump 25 stops, the purge pump 25 does not emit an operating noise. According to this configuration of the engine system, the engine 1 is in operation (when the engine 1 emits an operating noise), the purge valve 24 is open, and the purge pump 25 is operating (the purge pump 25 generates operating noise). When the engine 1 is temporarily stopped (for example, an idle stop request or an intermittent stop request), the pump rotational speed NP gradually decreases and the operation sound of the purge pump 25 is generated. The engine 1 is controlled so that the engine 1 stops when the engine becomes so small that it cannot be heard by the passenger of the vehicle 60. Therefore, when the operation sound of the purge pump 25 is loud enough to be heard by the occupant of the vehicle 60, the operation sound of the purge pump 25 is drowned out by the operation sound of the engine 1 because the engine 1 emits the operation sound without stopping. For this reason, when the engine 1 is temporarily stopped, the operating sound of the purge pump 25 can be prevented from being heard as an unpleasant noise. That is, the operation sound of the purge pump 25 can be made uncomfortable for the occupant of the vehicle 60.

  According to the configuration of this embodiment, the second predetermined value NP2 that is higher than the first predetermined value NP1 (the rotation speed at which the operation sound of the purge pump 25 is inaudible to the passenger of the vehicle 60) after the pump rotation speed NP starts to decrease. Since the engine speed NE begins to decrease when the operating speed of the purge pump 25 is reduced to a level that can be heard by the occupant of the vehicle 60, in the state where the pump speed NP is higher than the second predetermined value NP2, 1 continues to drive. When the pump speed NP reaches the first predetermined value NP1, the engine 1 stops (the engine speed NE becomes “0”), and the first predetermined value NP1 is held for a predetermined time. To the purge pump 25 (pump speed NP becomes “0”). Therefore, even if the engine 1 is stopped and the engine 1 is restarted shortly thereafter, the pump rotational speed NP is maintained at the first predetermined value NP1, so that the purge pump 25 can be easily restarted. For this reason, when the engine 1 is restarted in the middle of the temporary stop, the purge pump 25 can be promptly restarted, the electric power required for restarting the purge pump 25 can be reduced, and the purge flow rate of the vapor can be recovered. Can be expedited.

  Note that the disclosed technology is not limited to the above-described embodiment, and a part of the configuration can be changed as appropriate without departing from the spirit of the disclosed technology.

  (1) In the above embodiment, in the engine system not provided with the supercharger, the purge passage 23 is communicated with the intake passage 3 downstream from the throttle valve 11a to purge the vapor. On the other hand, in an engine system equipped with a supercharger, the vapor can be purged by connecting the purge passage to the intake passage upstream of the throttle valve and downstream of the air flow meter.

  (2) Although the idle stop and the intermittent stop are illustrated as the temporary stop of the engine 1 in the embodiment, the stop is not limited to these.

  (3) In the above-described embodiment, the engine 1 is stopped so that the engine 1 stops when the pump rotational speed NP becomes the first predetermined value NP1 to such an extent that the operating sound of the purge pump 25 cannot be heard by the occupant of the vehicle 60. Configured to control. On the other hand, the engine may be controlled so that the engine stops when the pump rotation speed NP becomes “0” when the operating noise of the purge pump becomes inaudible to the vehicle occupant.

  This disclosed technique can be applied to an engine system including an evaporated fuel processing apparatus.

1 Engine 3 Intake Passage 5 Fuel Tank 21 Canister 23 Purge Passage 24 Purge Valve 25 Purge Pump 30 Evaporative Fuel Treatment Device 50 ECU (Control Unit)
60 Vehicle NP Pump speed NP1 First predetermined value NP2 Second predetermined value NE Engine speed

Claims (2)

An engine system mounted on a vehicle,
An engine configured to be paused,
An intake passage for introducing intake air into the engine;
A fuel tank for storing fuel supplied to the engine;
An evaporative fuel processing device that once collects evaporative fuel generated in the fuel tank in a canister and purges the intake passage through a purge passage provided with a purge valve and a purge pump;
In an engine system comprising the engine, the purge valve, and a control means for controlling the purge pump,
When the control means receives a temporary stop request for the engine during operation of the engine and the purge pump, the rotational speed of the purge pump is gradually decreased after the request is received, An engine system that controls the engine so that the engine is stopped when an operation sound of the purge pump becomes low enough to be inaudible to passengers of the vehicle. The engine system according to claim 1, wherein
The purge pump rotational speed at which the operation sound of the purge pump is not audible to the vehicle occupant is defined as a first predetermined value, and the purge pump operation sound is audible to the vehicle occupant. And the second predetermined value as the number of rotations of
The control means starts to decrease the engine speed when the purge pump starts to decrease to the second predetermined value after the purge pump starts to decrease, and the purge pump reaches the first predetermined value. The engine system is stopped when the engine is stopped, and the purge pump is stopped after holding the first predetermined value for a predetermined time.

Images