JP2018119441A - Engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress residual water when an engine is stopped in an engine provided with a water injection device for injecting water into an intake passage or a combustion chamber. An intake passage 3 and an exhaust passage 4 connected to a combustion chamber 2 of an engine 1, a fuel injection valve 10 for injecting fuel, and a water injection device for injecting water into the combustion chamber 2 or the intake passage 3. 11, a timer 21 for acquiring an elapsed time T after the water injection by the water injection device 11 is last executed, an ignition switch 24 for instructing start and stop of engine operation, and an instruction for stopping engine operation. The engine control device is provided with the operation continuation control means 22 for continuing the idling of the engine for the predetermined time Y even after the instruction to stop the engine operation based on the elapsed time T. The operation continuation control unit 22 performs the continuous operation when the elapsed time T at the time of the stop instruction is less than the threshold value a. [Selection diagram] Figure 1

Description

  The present invention relates to an engine control device including a water injection device that injects water into an intake passage and a combustion chamber.

  Intake air is supplied into the combustion chamber of the engine through an intake passage provided in the cylinder head. A fuel injection valve is provided in the intake passage and the combustion chamber, and fuel injected from the fuel injection valve diffuses in the combustion chamber together with the intake air, and the diffused fuel burns in the combustion chamber.

  By the way, generally, when the temperature of the intake air rises, the charging efficiency of the intake air into the combustion chamber decreases. A decrease in the charging efficiency of the intake air hinders an improvement in output, and also causes knocking and deterioration of exhaust gas depending on the operation state. In particular, in an engine equipped with a supercharger or the like, the intake air temperature is likely to rise. To prevent this, various devices for reducing the intake air temperature such as an intercooler are added.

  Further, for example, Patent Documents 1 to 3 disclose techniques including a water injection device for cooling intake air in an intake passage. The intake air can be cooled by removing heat from the intake air when the water injected during the intake gasifies.

JP 2007-162667 A JP-A-5-10164 Japanese Patent Laid-Open No. 60-230554

  In an engine provided with the above water injection device, when the engine is stopped immediately after the water injection is performed, water remains in the combustion chamber or the intake passage. It is not preferable that water remains in the engine for a long time while the engine is stopped, because the durability of each part of the engine may be reduced.

  In addition to the water injected by the water injection device, the water remaining in the combustion chamber and the intake passage is due to various factors such as water contained in the fuel and water generated by the combustion of the fuel. Can also occur.

  Accordingly, an object of the present invention is to suppress water remaining in the combustion chamber or the intake passage when the engine is stopped.

  In order to solve the above problems, the present invention includes an intake passage and an exhaust passage connected to a combustion chamber of an engine, a fuel injection valve for injecting fuel, an ignition switch for instructing start and stop of engine operation, An operation continuation control means for continuously operating the engine idling for a predetermined time even after the instruction to stop the engine operation based on the remaining state of water in the combustion chamber or the intake passage at the time of the instruction to stop the engine operation. An engine control device is provided.

  The operation continuation control means includes a water injection device that injects water into the combustion chamber or the intake passage, and a timer that acquires an elapsed time after the water injection by the water injection device is last performed. Can adopt a configuration for grasping the residual state of the water based on the elapsed time when the engine operation stop instruction is given.

  At this time, the said operation continuation control means can employ | adopt the structure which performs the said continuous operation when the said elapsed time in the case of the said stop instruction | indication is less than a threshold value.

  In each of these aspects, the operation continuation control means may employ a configuration in which the predetermined time for idling is set longer as the elapsed time is shorter.

  In each of these aspects, the timer may be configured to stop counting the elapsed time while idling is stopped.

  Moreover, the said operation continuation control means can employ | adopt the structure which sets the said predetermined time based on the injection amount of the water at the time of performing the water injection by the said water injection apparatus last.

  In each of these aspects, an intake valve that opens and closes an opening of the intake passage to the combustion chamber, an exhaust valve that opens and closes an opening of the exhaust passage to the combustion chamber, and opening and closing timings of the intake valve and the exhaust valve A variable valve timing mechanism for adjusting the variable valve timing mechanism, and a valve control means for controlling the variable valve timing mechanism, wherein the operation continuation control means is a valve that simultaneously opens the intake valve and the exhaust valve during the continuous operation. A configuration for setting the overlap period can be employed.

  At this time, a throttle valve disposed in the intake passage and an ignition device disposed in the combustion chamber are provided, and the throttle valve is opened and the ignition is performed during the valve overlap period in the continuous operation. A configuration in which the ignition timing of the device is retarded can be employed.

  In the aspect provided with the valve control means, the valve control means is configured such that the temperature is equal to or higher than a predetermined temperature based on a temperature of cooling water for cooling the engine, a member constituting the engine, or intake air in the intake passage. Is set, the valve overlap period is set by delaying the closing timing of the exhaust valve, and when the temperature is lower than a predetermined temperature, the opening timing of the intake valve is advanced to set the valve over time. A configuration for setting a lap period can be employed.

  In each of these aspects, the operation continuation control means is configured to set the predetermined time based on the temperature of cooling water for cooling the engine, a member constituting the engine, or intake air in the intake passage. Can be adopted.

  In the present invention, the idling of the engine is continuously operated for a predetermined time even after the stop instruction of the engine operation based on the remaining state of the water in the combustion chamber or the intake passage at the time of the stop instruction of the engine operation. It is possible to suppress water remaining in the combustion chamber or the intake passage when the engine is stopped.

It is a principal part longitudinal cross-sectional view which shows embodiment of this invention. (A) (b) is a graph which shows the example of control of this invention. (A)-(c) is a graph which shows the example of control of this invention. (A) (b) is a graph which shows the example of control of this invention.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing the vicinity of a combustion chamber 2 and a cylinder head of an engine 1 of this embodiment.

  A piston 8 is accommodated in the cylinder of the engine 1. The combustion chamber 2 is formed by the upper surface of the cylinder, the inner peripheral surface, the upper surface of the piston 8, and the like. An intake port (hereinafter referred to as intake port 3) is provided as an intake passage 3 for sending intake air into the combustion chamber 2, and an exhaust port ( Hereinafter, it is referred to as an exhaust port 4).

  The intake port 3 includes a throttle valve 13 that adjusts the amount of intake air supplied to the combustion chamber 2 and a fuel injection valve (injector) 10 that injects fuel into the combustion chamber 2 and the intake port 3. . Further, an ignition device 7 is provided at the top of the combustion chamber 2 to burn the fuel supplied into the combustion chamber 2.

  An intake valve hole that is an opening of the intake port 3 to the combustion chamber 2 is opened and closed by the intake valve 5. Similarly, an exhaust valve hole that is an opening of the exhaust port 4 to the combustion chamber 2 is also opened and closed by the exhaust valve 6.

  In these drawings, members and means on the intake side that are directly related to the present invention are mainly shown, and other members and the like are not shown. Although only one cylinder is shown in the drawings, the engine 1 may be a single cylinder or a multi-cylinder having a plurality of cylinders.

  The cross-sectional shape of the intake port 3 is a so-called horizontally long oval shape in which the maximum diameter in the vertical direction connecting the upper surface 3a side and the lower surface 3b side of the passage is set smaller than the maximum diameter in the width direction perpendicular thereto. It has become. Such an oval shape is a section from the intake passage in the intake manifold arranged upstream of the intake port 3 to the vicinity of the valve support portion where the valve stem 5b of the intake valve 5 is supported by the cylinder head 1. Is continuing.

  The fuel injection valve 10 disposed in the intake port 3 is disposed such that the injection port faces the space in the intake port 3 from the upper surface 3a side of the intake port 3. By opening the valve of the injection port, the fuel is injected toward the downstream side along the intake flow direction.

  Further, in the intake port 3, a water injection device 11 that injects water into the intake port 3 and the combustion chamber 2 is disposed. Water is injected toward the downstream side from the supply port of the water injection device 11 along the intake flow direction indicated by an arrow in the drawing.

  Water is filled in a tank provided around the engine 1 or in any part of the vehicle on which the engine 1 is mounted, and is sent out from the tank to a supply port by a pump or the like. When the valve of the supply port is opened, the water jetted from the supply port becomes mist and goes from the intake port 3 into the combustion chamber 2, and most of the water is sequentially vaporized in the combustion chamber 2 ( Steam). And when water vaporizes, the intake air is cooled by taking heat away from the intake air.

  It is also possible to adopt a configuration in which the supply port of the water injection device 11 faces the combustion chamber 2. In this case, water is directly injected into the combustion chamber 2 from the supply port of the water injection device 11.

  A vehicle equipped with the engine 1 includes an electronic control unit 20. The electronic control unit 20 performs overall control of the engine 1 and auxiliary equipment including opening / closing control of the intake valve 5 and exhaust valve 6, control of fuel injection, control of ignition timing, and the like, as well as equipment mounted on the vehicle. Also controls.

  In addition, the electronic control unit 20 controls the water injection by the water injection device 11 when it is determined that the intake air needs to be cooled according to the operation state. Whether water injection is necessary is determined based on information such as intake air temperature, engine load, and rotational speed. The temperature of the intake air can be acquired by an intake air temperature sensor 15 provided in the intake port 3.

  A vehicle equipped with the engine 1 includes an ignition switch 24 that gives an instruction to start and stop the engine. When the driver turns on the ignition switch 24, the operation of the engine 1 is started. When the driver turns off the ignition switch 24, the operation of the engine 1 is immediately stopped in normal times.

  The electronic control unit 20 includes a timer 21 that acquires an elapsed time T after the last water injection by the water injection device 11. Since the water injection is performed according to the driving situation, the elapsed time T becomes relatively long when the ignition switch 24 is turned off after moving to the driving condition where the water injection is not performed after the last water injection. Tend. On the other hand, when the ignition switch 24 is turned off in an operation state in which water injection is performed, the elapsed time T tends to be relatively short.

  Further, the electronic control unit 20 is provided with an operation continuation control means 22 for continuously operating idling of the engine 1 for a predetermined time Y even after an instruction to stop the engine operation based on the elapsed time T at the time of the instruction to stop the engine operation. Yes.

  Here, the operation continuation control means 22 performs a control to perform the continuation operation only when the ignition switch 24 is turned off, that is, when the elapsed time T at the time of the engine operation stop instruction is less than a predetermined threshold value a. Is supposed to do. If the elapsed time T at the time of instructing to stop the engine operation is equal to or greater than the threshold value a, the water in the combustion chamber 2 and the intake port 3 has already been sufficiently discharged to the outside and there is no need for continuous operation. It is possible.

  Here, it is considered that the shorter the elapsed time T at the time of stopping the engine operation, the more water remains in the combustion chamber 2 and the intake port 3, so the predetermined time Y for continuous operation by idling is set longer. can do. For example, FIG. 2A shows a mode in which the predetermined time Y increases with a certain degree as the elapsed time T decreases in a region where the elapsed time T is less than the threshold value a. Further, FIG. 2B shows that when the elapsed time T is less than the threshold value a, the predetermined time Y is gradually set longer as the elapsed time T decreases, and the elapsed time T decreases when the unit time decreases. In this aspect, the increase amount of the predetermined time Y gradually increases as the elapsed time T decreases. In addition to these, various graphs, maps, and the like that guide the predetermined time Y by the elapsed time T can be adopted.

  Note that when determining the predetermined time Y based on the elapsed time T, the timer 21 may be set to stop counting the elapsed time T while idling is stopped. Further, at the time of idling stop, since the engine operation is resumed immediately thereafter, the continuous operation is not performed.

  In this way, the operation continuation control means 22 grasps the residual state of water in the combustion chamber 2 and the intake port 3 based on the elapsed time T when the engine operation stop instruction is given, and based on the elapsed time T. It is possible to determine the predetermined time Y during which continuous operation is performed. However, in addition to the element of the elapsed time T, the remaining state of water in the combustion chamber 2 and the intake port 3 is grasped based on various factors. The predetermined time Y can be determined.

  For example, the operation continuation control means 22 grasps the remaining state of water on the basis of the water injection amount W when the water injection by the water injection device 11 is last performed, and determines the predetermined time Y for performing the continuous operation. Is possible. The water injection amount W at the time of the last water injection refers to the operation region in which water injection is not performed from the operation state in which water injection is performed among the water injections performed for a certain amount of time for each combustion cycle. It can be defined as the amount of water injected in the last combustion cycle before the transition at the time of transition. Or it can prescribe | regulate as the injection amount of the water injected in the last combustion cycle at the time of turning off the ignition switch 24 in the driving | running condition which performs water injection.

  At this time, as the water injection amount W at the time of the last water injection increases, the remaining amount of water in the combustion chamber 2 and the intake port 3 increases, so the predetermined idling time Y can be set longer. it can. For example, as shown in FIG. 3A, the predetermined time Y is set to increase as the water injection amount W increases in the region where the last water injection amount W is greater than or equal to the threshold value b. Here, as shown in the figure, the predetermined time Y may increase at a certain degree as the water injection amount W increases, and the water injection amount W increases as the water injection amount W increases. It is good also as an aspect etc. which the increase amount of the predetermined time Y at the time of increasing increases gradually. Note that the threshold value b may be zero. In addition to these, various graphs, maps, and the like that guide the predetermined time Y by the water injection amount W can be employed.

  Alternatively, the operation continuation control means 22 may be a cooling water that cools the engine 1, a member that constitutes the engine 1 (for example, the intake port 3, the exhaust port 4, the cylinder block, etc.) It is also possible to determine the remaining time of water based on the temperature S and set the predetermined time Y. Here, the information on any one temperature S may be adopted as an element for setting the predetermined time Y, and representative values (average value, maximum value, etc.) based on the information on a plurality of temperatures S are used for the predetermined time. You may employ | adopt as an element for setting Y.

  The temperature of the cooling water can be acquired by the cooling water temperature sensor 14 provided in the cooling water passage of the engine 1. The temperature of the members constituting the engine 1 is a temperature sensor (not shown) provided in the component of the engine 1 that is the target of temperature acquisition, and the temperature of the intake air in the intake port 3 is Can be obtained by the intake air temperature sensor 15.

  The lower the temperature S is, the more water is left in the combustion chamber 2 and the intake port 3, so that the predetermined idling time Y can be set longer. For example, as shown in FIG. 3B, in a region where the temperature S is less than the threshold value c, the predetermined time Y is set to increase as the temperature S decreases. Here, as shown in the figure, as the temperature S decreases, the predetermined time Y may increase at a certain degree, or as the temperature S decreases, the predetermined time Y increases when the temperature S decreases by a unit temperature. For example, the amount may be gradually increased. In addition to these, various graphs, maps, and the like that guide the predetermined time Y according to the temperature S can be employed.

  Alternatively, the operation continuation control means 22 grasps the remaining state of water based on the water detection information of the water detection means 12 provided in the combustion chamber 2 or the intake port 3, and determines the predetermined time Y for performing the continuous operation. It is possible. As the water detection means 12, it can carry out by employ | adopting a known humidity sensor etc., for example. The water detection means 12 detects the residual amount R of water in the intake port 3 as the residual state of water.

  For example, as shown in FIG. 3C, the predetermined time Y is set to increase as the residual water amount R increases in a region where the residual water amount R is greater than or equal to the threshold value d. Here, as shown in the figure, as the residual amount R of water increases, the predetermined time Y may increase at a certain degree, or the residual amount R of water becomes a unit amount as the residual amount of water R increases. It is good also as an aspect etc. which the increase amount of the predetermined time Y at the time of increasing increases gradually. Note that the threshold value d may be zero. In addition to these, various graphs, maps, and the like that guide the predetermined time Y by the residual amount R of water can be employed.

  The information on the water injection amount W, the temperature S, and the water residual amount R can be used as an element for correcting and correcting the predetermined time Y determined by the elapsed time T.

  For example, as the water injection amount W (the water injection amount W when the water injection is last performed) is larger, the predetermined time Y determined by the elapsed time T can be corrected. In addition, when the water injection amount W is equal to or greater than a predetermined amount, it is possible to make a correction for executing the continuous operation even if the elapsed time T is equal to or greater than the threshold value a.

  Similarly, the correction that increases the predetermined time Y determined by the elapsed time T can be performed as the temperature S is lower or the remaining amount R of water is larger. Alternatively, when the temperature S is lower than a predetermined temperature, or when the remaining amount R of water is equal to or greater than a predetermined amount, it is possible to perform a correction for executing continuous operation even if the elapsed time T is equal to or greater than the threshold value a. is there.

  Further, even when the continuous operation exceeds the predetermined time Y, if the remaining amount R of water detected by the water detection means 12 detects water of a predetermined amount or more, a correction is made to continue the continuous operation further. May be.

  When continuous operation for a predetermined time Y determined by each of the above methods is performed, if a valve overlap period is set for the intake valve 5 and the exhaust valve 6, water remaining in the combustion chamber 2 and the intake port 3 is further suppressed. can do. By setting the valve overlap period, the water discharge performance due to the scavenging effect from the intake port 3 side to the exhaust port 4 side in the combustion chamber 2 is enhanced, and the blowback from the exhaust port 4 side to the intake port 3 side is performed. This is because the water evaporation performance due to the effect is enhanced.

  The valve overlap period can be set in the engine 1 having the variable valve timing mechanism 9 that adjusts the opening / closing timing of the intake valve 5 and the exhaust valve 6. The variable valve timing mechanism 9 is controlled by valve control means 23 provided in the electronic control unit 20.

  By opening the throttle valve 13 and retarding the ignition timing of the ignition device 7 during the valve overlap period in the continuous operation, the intake amount can be increased and the scavenging effect can be further enhanced.

  Further, when setting the valve overlap period, the valve control means 23 closes the exhaust valve 6 as shown in FIG. 4A when the temperature S is equal to or higher than the predetermined temperature based on the temperature S described above. The valve timing is retarded from the normal operation state. Symbol E in the figure indicates the operation of the exhaust valve 6 in the normal operation state, and symbol I indicates the operation of the intake valve 5 in the normal operation state. Reference symbol E ′ indicates the operation of the exhaust valve 6 after being retarded. Here, the lift amount is large and the valve opening amount is large as it goes upward in the graph. In this way, the valve overlap period is set by the delay of the closing timing of the exhaust valve 6, thereby improving the scavenging effect in the combustion chamber 2 and allowing the remaining water to be easily discharged to the outside. Can be set.

  Further, when the temperature S is lower than the predetermined temperature based on the temperature S, the temperature of the members constituting the engine 1 is low and the water does not evaporate smoothly. Therefore, as shown in FIG. 5 is advanced from the normal operation state. Reference symbol I ′ in the figure indicates the operation of the intake valve 5 after the advance. In this way, the valve overlap period is set by the advance angle of the opening timing of the intake valve 5, and accordingly, even when the members constituting the engine 1 are at a relatively low temperature, the intake port 3 from the exhaust port 4 side. It is possible to set a situation in which the effect of blowing back to the side is increased to raise the temperature of the intake air, the remaining water is evaporated, and the water is easily discharged to the outside.

  When the valve overlap period is set in the continuous operation, a valve overlap period is set in the preceding stage based on the advance angle of the opening timing of the intake valve 5 aiming at the blowback effect, and in the subsequent stage, the scavenging is performed. You may set the valve overlap period aiming at an effect. For example, the valve overlap period aiming at the upstream blow-back effect can be made half the time, and the valve overlap period aiming at the subsequent stage scavenging effect can be made half the whole.

  However, when the supply port of the water injection device 11 faces the combustion chamber 2 directly, the amount of water remaining in the intake port 3 is limited to that caused by other than water injection, and the amount thereof is relatively small. Become. For this reason, it is considered that the setting of the valve overlap period aiming at the above-described blowback effect is relatively less important than the setting of the valve overlap period aiming at the scavenging effect. For this reason, when the supply port of the water injection device 11 directly faces the combustion chamber 2, it is desirable to set the valve overlap period by delaying the closing timing of the exhaust valve 6.

  In each of the above embodiments, the water injection by the water injection device 11 is intended for the purpose of cooling the intake air. However, in addition to the water injection for the purpose of cooling the intake air, for example, mixing in the combustion chamber 2 The present invention can also be applied to the engine 1 including the water injection device 11 for the purpose of air rectification and extrusion. Furthermore, even in the engine 1 that does not include the water injection device 11, water into the combustion chamber 2 and the intake port 3 due to various factors such as water contained in the fuel and water generated by the combustion of the fuel. Since a residue can occur, the present invention can be applied to suppress the residue of the water. The present invention can be applied not only to gasoline engines but also to other types of engines such as diesel engines.

1 Engine 2 Combustion chamber 3 Intake port (intake passage)
4 Exhaust port (exhaust passage)
5 Intake valve 6 Exhaust valve 7 Ignition device 8 Piston 9 Variable valve timing mechanism 10 Fuel injection valve 11 Water injection device 12 Water detection means 13 Throttle valve 14 Temperature sensor 20 Electronic control unit 21 Timer 22 Operation continuation control means 23 Valve control means 24 Ignition switch

Claims (10)

An intake passage and an exhaust passage connected to the combustion chamber of the engine;
A fuel injection valve for injecting fuel;
An ignition switch for instructing start and stop of engine operation;
An operation continuation control means for continuously operating idling of the engine for a predetermined time even after the instruction to stop the engine operation based on the remaining state of water in the combustion chamber or the intake passage at the time of the instruction to stop the engine operation;
An engine control device comprising: A water injection device for injecting water into the combustion chamber or the intake passage;
A timer for obtaining an elapsed time after the last water injection by the water injection device;
With
The engine control device according to claim 1, wherein the operation continuation control unit grasps the remaining state of the water based on the elapsed time when the engine operation stop instruction is issued. The engine control device according to claim 2, wherein the operation continuation control unit performs the continuous operation when the elapsed time at the time of the stop instruction is less than a threshold value. The engine control device according to claim 2 or 3, wherein the operation continuation control means sets the predetermined time for idling longer as the elapsed time is shorter. The engine control device according to any one of claims 2 to 4, wherein the timer stops counting the elapsed time while idling is stopped. The engine control according to any one of claims 2 to 5, wherein the operation continuation control unit sets the predetermined time based on a water injection amount when the water injection by the water injection device is finally performed. apparatus. An intake valve for opening and closing an opening of the intake passage to the combustion chamber;
An exhaust valve for opening and closing an opening of the exhaust passage to the combustion chamber;
A variable valve timing mechanism for adjusting the opening and closing timing of the intake valve and the exhaust valve;
Valve control means for controlling the variable valve timing mechanism;
With
The engine control device according to any one of claims 1 to 6, wherein the operation continuation control means sets a valve overlap period in which the intake valve and the exhaust valve are simultaneously opened during the continuous operation. A throttle valve disposed in the intake passage;
An ignition device disposed in the combustion chamber;
With
The engine control device according to claim 7, wherein the throttle valve is opened and the ignition timing of the ignition device is retarded during the valve overlap period in the continuous operation. The valve control means closes the exhaust valve when the temperature is equal to or higher than a predetermined temperature based on the temperature of cooling water for cooling the engine, a member constituting the engine, or intake air in the intake passage. The valve overlap period is set by retarding the valve timing, and when the temperature is lower than a predetermined temperature, the valve overlap period is set by advancing the valve opening timing of the intake valve. The engine control device according to claim 8. The said operation continuation control means sets the said predetermined time based on the temperature of either the cooling water which cools the said engine, the member which comprises the said engine, or the intake air in the said intake passage. The engine control device according to claim 1.

Images