JP6514574B2 - Engine system - Google Patents

Description

The present invention relates to an engine system that ignites injected into the combustion chamber the fuel.

  As the engine, for example, a port injection method for injecting fuel into an intake port described in Patent Document 1 and a direct injection method for directly injecting fuel into a combustion chamber described in Patent Documents 2 and 3 are described. is there. Further, Patent Documents 1 to 3 each describe a configuration in which a plurality of spark plugs are provided, and a technique for the firing order of the spark plugs is disclosed.

  For example, in Patent Document 1, the swirl flow of intake air in which the fuel after injection is mixed is estimated by simulation, and ignition is performed from the spark plug positioned on the side where the fuel concentration is high. Moreover, in patent document 2, it ignites from the ignition plug located in the side where fuel concentration is low, and, in patent document 3, the ignition order of the ignition plug is changed according to the driving | running condition of an engine.

JP, 2014-173574, A JP, 2009-222030, A Patent No. 3627546 gazette

  As described in Patent Documents 1 to 3 described above, it is desirable that the firing order by the plurality of spark plugs be set according to the concentration distribution of the fuel. Further, not only the order of ignition of a plurality of spark plugs, but also with which spark plug it is possible to appropriately set the concentration distribution of fuel if it is known. However, the flow of intake air in the combustion chamber may vary due to the influence of cycle fluctuation and the like, and even if the concentration distribution of the fuel is estimated by simulation or the like, it may actually deviate from the estimation result. Therefore, among the plurality of spark plugs, ignition by the appropriate spark plug is not performed, and the combustion stability is reduced.

Accordingly, an object of the present invention to provide an engine system which can improve the combustion stability.

In order to solve the above problems, an engine system according to the present invention, wherein fuel is injected from a fuel injection port provided in a combustion chamber, and then the injected fuel is ignited by at least one of a plurality of spark plugs. Among the plurality of temperature sensors provided in the combustion chamber and provided for each of the plurality of spark plugs and the plurality of temperature sensors, the temperature drops most during the period from the fuel injection to the combustion chamber until the ignition. And a controller for igniting the fuel by the spark plug provided with a large temperature sensor .
In order to solve the above problems, after fuel is injected from a fuel injection port provided in a combustion chamber, the injected fuel is ignited by at least one of a plurality of spark plugs. The engine system is disposed in the combustion chamber, and among the plurality of temperature sensors provided in each of the plurality of spark plugs and the plurality of temperature sensors, a temperature drop occurs after fuel is injected into the combustion chamber and then ignited. And a control unit configured to ignite the fuel by an ignition plug provided with a temperature sensor having a predetermined width or more.

  The spark plug has a first electrode projecting from the inner wall of the combustion chamber to the combustion chamber, and a second electrode projecting to the combustion chamber from the first electrode to a position spaced apart from the inner wall. The spark plug discharges due to the voltage difference between the electrode and the second electrode, and the temperature sensor has a sensor unit whose electric resistance changes due to a temperature change, and a wire unit for energizing the sensor unit. , May be provided on the second electrode.

  According to the present invention, it is possible to improve the combustion stability.

It is a schematic diagram showing composition of an engine system. It is a schematic sectional drawing of the combustion chamber vicinity in a cylinder. It is an extraction figure of the spark plug vicinity in FIG. It is an explanatory view for explaining ignition processing by a spark plug. It is a flowchart which shows the flow of the ignition processing by a spark plug. It is a flowchart which shows the flow of the ignition processing by the spark plug in a modification.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values and the like shown in this embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the specification and the drawings, elements having substantially the same functions and configurations will be denoted by the same reference numerals to omit repeated description, and elements not directly related to the present invention will not be illustrated. Do.

  FIG. 1 is a schematic view showing the configuration of an engine system 100 according to the present embodiment. In FIG. 1, the flow of the signal is indicated by a broken arrow. As shown in FIG. 1, the engine system 100 is provided with an ECU (Engine Control Unit) 110 which is a microcomputer including a central processing unit (CPU), a ROM storing programs and the like, and a RAM as a work area. The entire engine 120 is centrally controlled by the ECU 110. However, in the following, configurations and processes related to the present embodiment will be described in detail, and descriptions of configurations and processes not related to the present embodiment will be omitted.

  The engine 120 is a multi-cylinder engine having a plurality of cylinders 122 a, and an intake manifold 126 is in communication with an intake port 124 of each cylinder 122 a formed in the cylinder block 122. An intake passage 130 is communicated with the collecting portion of the intake manifold 126 via an air chamber 128, an air cleaner 132 is provided on the upstream side of the intake passage 130, and a throttle valve 134 is provided on the downstream side of the air cleaner 132.

  Further, an exhaust manifold 138 is in communication with the exhaust port 136 of each cylinder 122 a formed in the cylinder block 122 of the engine 120. An exhaust passage 140 is in communication with a collection portion of the exhaust manifold 138, and a catalyst device 142 is provided in the exhaust passage 140.

  FIG. 2 is a schematic cross-sectional view of the vicinity of the combustion chamber 144 in the cylinder 122a. As shown in FIG. 2, a cylinder head 146 is connected to the cylinder block 122, and a space surrounded by the cylinder head 146 and the crown surface of the piston 150 at the top dead center is It is a combustion chamber 144.

  The injector 152 and the spark plug 154 are fixed to the cylinder head 146. A plurality of (here, three) spark plugs 154 are provided for the cylinder 122a. Hereinafter, when the three spark plugs 154 are distinguished, they are referred to as a spark plug 154a, a spark plug 154b, and a spark plug 154c in order from the left side in FIG.

  Further, a fuel injection port 152a formed at the tip end of the injector 152 opens into the combustion chamber 144, and injects fuel stored in a fuel gallery (not shown) from the fuel injection port 152a to the combustion chamber 144. The fuel injected into the combustion chamber 144 mixes with the intake air supplied to the combustion chamber 144 to form an air-fuel mixture. The mixture thus generated is combusted by being ignited by the spark plug 154, and an explosion pressure is generated in the combustion chamber 144. The explosion pressure causes the piston 150 to be driven in the cylinder liner 148 toward the bottom dead center.

  One end of a connecting rod 156 is connected to the piston 150, and a crankshaft 158 is connected to the other end of the connecting rod 156. As a result, the linear movement of the piston 150 is converted to the rotational movement of the crankshaft 158.

  The cylinder head 146 is also provided with an intake valve 160 for opening and closing the intake port 124 and an exhaust valve 162 for opening and closing the exhaust port 136. When the intake valve 160 opens, the intake manifold 126 and the combustion chamber 144 communicate with each other, and the intake port 124 allows intake air to flow from the intake manifold 126 into the combustion chamber 144. When the exhaust valve 162 opens, the exhaust manifold 138 and the combustion chamber 144 communicate with each other, and the exhaust port 136 causes the combustion gas in the combustion chamber 144 to flow out.

  FIG. 3 is an extracted view of the vicinity of the spark plug 154 in FIG. As shown in FIG. 3, the ignition plug 154 is inserted into a plug hole 146 a provided in the cylinder head 146, and the tip end side of the ignition plug 154 is disposed so as to protrude from the inner wall 144 a (cylinder head 146) of the combustion chamber 144.

  Specifically, the spark plug 154 is a spark plug that discharges due to a voltage difference, and includes a center electrode 170 (first electrode) and an outer electrode 172 (second electrode). The main body portion 174 of the spark plug 154 is accommodated in the plug hole 146 a, and the center electrode 170 attached to the main body portion 174 linearly protrudes from the inner wall 144 a of the combustion chamber 144 to the combustion chamber 144.

  On the other hand, the outer electrode 172 protrudes approximately parallel to the center electrode 170 from the tip of the center electrode 170 to a position separated from the inner wall 144 a of the combustion chamber 144. Further, the outer electrode 172 is bent toward the center electrode 170 at a position separated from the cylinder head 146 from the tip of the center electrode 170. An opposing portion 172 a of the outer electrode 172 extending toward the center electrode 170 faces the tip 170 a of the center electrode 170 at a predetermined interval in the extending direction of the center electrode 170.

  The center electrode 170 is electrically connected to a coil (not shown), and the outer electrode 172 is electrically connected to the cylinder head 146 (earth). Then, when a voltage is applied to the center electrode 170, the spark plug 154 discharges due to the voltage difference between the tip 170 a of the center electrode 170 and the facing portion 172 a of the outer electrode 172.

  Further, of the facing portion 172a of the outer electrode 172, the sensor portion 180a is provided on the surface opposite to the center electrode 170. The sensor unit 180a is made of a material (swing material) having a low thermal conductivity and a small heat capacity, for example, a heat shielding film made of a SiC binder or high purity glass beads, and the electric resistance changes due to a temperature change.

  In the sensor unit 180a, a wire unit 180b configured by two wires is electrically connected to both ends. The wire portion 180 b extends to the outside of the combustion chamber 144, and electricity is conducted from the outside of the combustion chamber 144 to energize the sensor portion 180 a.

  The temperature sensor 180 is configured by the sensor unit 180a and the electric wire unit 180b, and the plug unit P is configured by the spark plug 154 and the temperature sensor 180.

  Returning to FIG. 1, in the engine system 100, in addition to the above-described temperature sensor 180, a crank angle sensor 182 for detecting a crank angle of the crankshaft 158 and an accelerator for detecting an opening degree of an accelerator (not shown). An opening sensor 184 is provided.

  Each of the sensors 180 to 184 is connected to the ECU 110, and outputs a signal indicating a detected value to the ECU 110.

  The ECU 110 controls the engine 120 by acquiring signals output from the sensors 180 to 184. When the ECU 110 controls the engine 120, the signal acquisition unit 190, the target value derivation unit 192, the air amount determination unit 194, the injection amount determination unit 196, the throttle opening determination unit 198, the ignition timing determination unit 200, and the drive control unit 202. It functions as a (control unit).

  The signal acquisition unit 190 acquires a signal indicating a value detected by each of the sensors 180 to 184. The target value deriving unit 192 derives the current engine rotational speed based on the signal indicating the crank angle acquired from the crank angle sensor 182. In addition, target value derivation unit 192 refers to a map stored in advance based on the derived engine rotational speed and a signal indicating the accelerator opening acquired from accelerator opening sensor 184, to obtain the target torque and target engine rotation. Derive the number.

  The air amount determination unit 194 determines a target air amount to be supplied to each cylinder 122 a based on the target engine speed and the target torque derived by the target value derivation unit 192. The throttle opening degree determination unit 198 derives the total amount of the target air amounts of the cylinders 122a determined by the air amount determination unit 194, and determines a target throttle opening degree for drawing the total amount of air from the outside.

  Based on the target air amount of each cylinder 122a determined by the air amount determination unit 194, the injection amount determination unit 196 sets, for example, the fuel to be supplied to each cylinder 122a so that the air fuel ratio becomes leaner than the theoretical air fuel ratio. Determine the target injection amount. As described above, the engine 120 performs stratified lean combustion in which the fuel concentration partially forms a layer while suppressing the fuel concentration in the entire combustion chamber 144 by suppressing the fuel injection amount at low load. .

  Further, the injection amount determination unit 196 sets each target injection amount based on the signal indicating the crank angle detected by the crank angle sensor 182 in order to inject the determined target injection amount from the injector 152 in the intake stroke or compression stroke of the engine 120. The target injection timing and target injection period of the injector 152 are determined.

  The ignition timing determination unit 200 determines the target of the ignition plug 154 in each cylinder 122a based on the target engine rotational speed derived by the target value derivation unit 192 and the signal indicating the crank angle detected by the crank angle sensor 182. Determine the ignition timing.

  The drive control unit 202 drives a throttle valve actuator (not shown) such that the throttle valve 134 is opened at the target throttle opening degree determined by the throttle opening degree determination unit 198. Further, the drive control unit 202 causes the injector 152 to inject the fuel of the target injection amount by driving the injector 152 at the target injection timing and the target injection period determined by the injection amount determination unit 196.

  Further, the drive control unit 202 ignites any one of the plurality of spark plugs 154 at the target ignition timing determined by the ignition timing determination unit 200. At this time, which spark plug 154 is used for ignition is properly set if the concentration distribution of the fuel is known. However, the flow of intake air in the combustion chamber 144 has variations due to the influence of cycle fluctuation and the like, and even if the concentration distribution of fuel is estimated by simulation etc., it may actually deviate from the estimation result. Therefore, the drive control unit 202 causes the fuel to be ignited by the spark plug 154 of one or more of the plurality of spark plugs 154 based on the temperature in the combustion chamber 144 measured by the temperature sensor 180.

  FIG. 4 is an explanatory view for explaining the ignition processing by the spark plug 154, and shows a schematic view of the combustion chamber 144 as viewed from the cylinder liner 148 side. As shown in FIG. 4A, the intake port 124 and the exhaust port 136 respectively open to the combustion chamber 144 at two points. The three spark plugs 154 pass between two openings of the intake port 124 and between two openings of the exhaust port 136 at a portion of the cylinder head 146 that forms the inner wall of the combustion chamber 144. It arrange | positions on a line (it shows with a dashed-dotted line in FIG. 4).

  Then, it is assumed that the fuel injected from the injector 152 is relatively relatively distributed, for example, in the range of the circle Sa shown in FIG. 4 (a). The injected fuel is vaporized inside the combustion chamber 144 while taking the heat of the surrounding intake air (air-fuel mixture). At this time, the temperature of the intake air in the range of the circle Sa is the lowest. Therefore, among the temperature sensors 180 provided in the three spark plugs 154, the largest temperature drop is measured in the temperature sensor 180 provided in the spark plug 154b.

  Further, as shown in FIG. 4B, when the fuel injected from the injector 152 is relatively distributed, for example, in the range of the circle Sb, among the temperature sensors 180 provided in the three spark plugs 154, The largest temperature drop is measured by the temperature sensor 180 provided in the spark plug 154a.

  Further, as shown in FIG. 4C, when the fuel injected from the injector 152 is relatively distributed, for example, in the range of the circle Sc, among the temperature sensors 180 provided in the three spark plugs 154, The largest temperature drop is measured by the temperature sensor 180 provided in the spark plug 154c.

  As described above, if the temperature of the combustion chamber 144 is measured by the temperature sensor 180, it is possible to identify the spark plug 154 at a position where the concentration of fuel unevenly distributed in the combustion chamber 144 is relatively high.

  The drive control unit 202 is, among the plurality of temperature sensors 180, the period from the injection of fuel into the combustion chamber 144 to the ignition (from the crank angle at which fuel injection is performed to the crank angle at which ignition is performed). The fuel is ignited in the spark plug 154 provided with the temperature sensor 180 having a large temperature drop.

  As described above, since the engine 120 performs stratified lean combustion, it is possible to improve the stability of ignition by igniting the fuel by the spark plug 154 which is estimated to be close to the highest concentration range of the fuel. it can. In addition, since the other spark plugs 154 are not discharged, the deterioration of the spark plugs 154 can be suppressed and the power consumption can be suppressed.

  FIG. 5 is a flow chart showing the flow of the ignition process by the spark plug 154. The process shown in FIG. 5 is performed between the intake stroke of engine 120 and the compression stroke.

(Fuel injection processing S300)
The drive control unit 202 causes the injector 152 to inject the fuel of the target injection amount by driving the injector 152 at the target injection timing and the target injection period determined by the injection amount determination unit 196.

(Predetermined time lapse determination processing S302)
The drive control unit 202 determines whether or not a predetermined time has elapsed after fuel injection. As a result, when it is determined that the predetermined time has elapsed, the process proceeds to the temperature decrease comparison process S304. If it is determined that the predetermined time has not elapsed, the predetermined time elapse determination processing S302 is repeated. Here, the predetermined time is the time from the fuel injection to the application to the spark plug 154, and is determined by the fuel injection period, the engine speed, and the like.

(Temperature reduction comparison processing S304)
The drive control unit 202 compares the reduction width from the time of fuel injection with respect to the temperature in the combustion chamber 144 measured by the plurality of temperature sensors 180, and specifies the temperature sensor 180 having the largest reduction width.

(Ignition processing S306)
The drive control unit 202 applies a voltage to the spark plug 154 provided with the temperature sensor 180 identified in the temperature decrease comparison process S304 to cause the fuel in the combustion chamber 144 to be ignited, and the process is completed.

  As described above, in the engine 120, since the fuel is ignited by the spark plug 154 provided with the temperature sensor 180 having the largest temperature reduction width, the stability of the ignition can be improved, and all of the spark plugs 154 can be improved. While suppressing the deterioration of the spark plug 154, power consumption can be suppressed as compared with the case where the voltage is applied.

  In the embodiment described above, the case where the fuel is ignited by the spark plug 154 provided with the temperature sensor 180 having the largest temperature reduction width has been described. In the modification, the drive control unit 202 selects an igniter plug for igniting the fuel by another process.

  FIG. 6 is a flowchart showing the flow of the ignition process by the spark plug 154 in the modification. About the same processing as embodiment mentioned above, in order to avoid duplication, the same numerals are attached and explanation is omitted.

(Deterioration determination processing S356)
The drive control unit 202 compares the reduction width from the time of fuel injection with the predetermined width set in advance for the temperature in the combustion chamber 144 measured by the plurality of temperature sensors 180, and the reduction width is not less than the predetermined width It is determined whether the temperature sensor 180 is present. If it is determined that there is a temperature sensor 180 whose decrease width is equal to or greater than the predetermined width, the process proceeds to the predetermined width ignition processing S358. If it is determined that there is no temperature sensor 180 having a reduction width equal to or greater than a predetermined width, the process proceeds to an ignition processing S306 in which ignition is performed by the spark plug 154 provided with the temperature sensor 180 having the maximum reduction width.

(Predetermined width ignition processing S 358)
The drive control unit 202 is provided with a temperature sensor 180 having a temperature decrease (temperature decrease width) equal to or greater than a predetermined width before fuel is injected into the combustion chamber 144 and then ignited among the plurality of temperature sensors 180. The fuel is ignited by the igniter plug 154.

  In the modification, as in the embodiment described above, it is possible to improve the stability of ignition, to suppress the deterioration of the spark plug 154, and to suppress the power consumption. Furthermore, in the case where there are a plurality of temperature sensors 180 in which the temperature decrease width has become equal to or greater than a predetermined width, the fuel spread over a wide range can be ignited at a plurality of places, and the ignition stability is further improved.

  Although the embodiment and the modification which were mentioned above explained the case where three spark plugs 154 were provided in one combustion chamber 144, two spark plugs 154 may be used or four or more. Further, although the case where the fuel is ignited by one spark plug 154 among the three spark plugs 154 has been described, the fuel may be ignited by a plurality of spark plugs 154 (including the case of all the spark plugs 154). .

  In the embodiment and the modification described above, the stratified lean combustion is performed in the combustion chamber 144. However, the combustion chamber 144 is not limited to the stratified lean combustion, and may be applied to the direct injection type engine 120 The following combustion method may be used. Alternatively, the fuel may be ignited by an ignition plug 154 located in a range where the temperature decrease width of the temperature sensor 180 is small and the concentration of the fuel is estimated to be relatively low according to the combustion method.

  When the temperature sensor 180 is provided on the outer electrode 172, there is no need to provide a separate member projecting to the combustion chamber 144 to install the temperature sensor 180. Therefore, the number of parts is reduced and the gas in the combustion chamber 144 is It is possible to reduce the impact on the flow of Furthermore, the configuration in which the temperature sensor 180 (sensor unit 180a) is provided only on the outer electrode 172 makes it possible to suppress the temperature rise of the sensor unit 180a and the electrode itself as compared to the case where the temperature sensor 180 is provided on the center electrode 170. Can be suppressed.

  In particular, in the configuration in which the sensor portion 180a is fixed to a part of the facing portion 172a of the outer electrode 172 on the opposite side to the center electrode 170, the temperature near the sensor portion 180a is easily lowered by the fuel. The occurrence can be further suppressed. Further, by using the heat shield film provided on the outer electrode 172 as a material having a low thermal conductivity and a small heat capacity, it is possible to synergistically suppress the occurrence of pre-ignition and also improve the response of the temperature sensor 180. .

  Moreover, although the case where the temperature sensor 180 is provided in each of the plurality of spark plugs 154 has been described in the embodiment and the modification described above, the temperature sensor 180 may be provided in two or more spark plugs 154. However, by providing the temperature sensor 180 for each of the plurality of spark plugs 154, it is possible to measure the temperature in the vicinity of each spark plug 154, and it becomes possible to select a more appropriate spark plug 154.

  Further, in the embodiment described above, the drive control unit 202 is provided with the temperature sensor 180 having the largest temperature drop in the period from the fuel injection to the combustion chamber 144 to the ignition among the plurality of temperature sensors 180. The case where the fuel is ignited by the spark plug 154 is described. Further, in the above-described modification, the drive control unit 202 is a temperature sensor 180 of which the temperature decrease is equal to or greater than a predetermined width before fuel is injected into the combustion chamber 144 and then ignited, among the plurality of temperature sensors 180. The case where the fuel is ignited by the spark plug 154 provided with. However, the control of selecting the spark plug 154 to be used for ignition from the temperature measured by the temperature sensor 180 is not limited to these examples.

  Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is obvious that those skilled in the art can conceive of various changes or modifications within the scope of the claims, and it is naturally understood that they are also within the technical scope of the present invention. Be done.

The present invention is applicable to an engine system that ignites injected into the combustion chamber the fuel.

P plug unit 100 engine system 120 engine 144 combustion chamber 152a fuel injection port 154, 154a, 154b, 154c spark plug (spark plug)
170 Center electrode (first electrode)
172 Outer electrode (second electrode)
180 Temperature sensor 180a Sensor unit 180b Electric wire unit 202 Drive control unit (control unit)

Claims (3)

An engine system in which fuel is injected from a fuel injection port provided in a combustion chamber, and then the injected fuel is ignited by at least one of a plurality of spark plugs.
A plurality of temperature sensors disposed in the combustion chamber and provided to each of a plurality of spark plugs ;
Among the plurality of temperature sensors, a control unit which causes the fuel to be ignited by the spark plug provided with the temperature sensor having the largest temperature decrease in the period from the injection of the fuel into the combustion chamber to the ignition thereof ;
An engine system comprising:   An engine system in which fuel is injected from a fuel injection port provided in a combustion chamber, and then the injected fuel is ignited by at least one of a plurality of spark plugs.
  A plurality of temperature sensors disposed in the combustion chamber and provided to each of a plurality of spark plugs;
  A control unit for igniting the fuel by the spark plug provided with a temperature sensor whose temperature decrease is equal to or more than a predetermined width before fuel is injected into the combustion chamber and then ignited among the plurality of temperature sensors; ,
An engine system comprising: The spark plug is
A first electrode protruding from an inner wall of the combustion chamber to the combustion chamber;
A second electrode protruding from the first electrode to a position separated from the inner wall in the combustion chamber;
A spark plug that discharges due to a voltage difference between the first electrode and the second electrode,
The temperature sensor is
A sensor unit whose electric resistance changes due to a temperature change,
A wire unit for energizing the sensor unit;
Have
The sensor unit, the engine system according to claim 1 or 2, characterized in that provided on the second electrode.

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