JP5649160B2 - Engine operating method, engine, and spark plug provided in the engine - Google Patents

Description

  According to the present invention, an ignition plug having an ignition chamber formed in a plug cover that covers an ignition point is attached to a cylinder head, and a communication hole that connects the ignition chamber and a combustion chamber facing a piston is provided in the plug cover. The present invention relates to an engine operating method, an engine, and a spark plug provided in the engine.

  The spark plug provided in the engine as described above forms an ignition chamber having an ignition point in the plug cover by providing a plug cover on the plug body. In the engine as described above, the spark plug is connected to the cylinder so that the plug cover protrudes from the cylinder head side to the combustion chamber facing the piston so that the ignition chamber and the combustion chamber communicate with each other through one or more communication holes. It is attached to the head. Then, an air-fuel mixture such as a lean air-fuel mixture sucked into the combustion chamber is compressed as the piston rises, and the compressed air-fuel mixture flows into the ignition chamber through the communication hole. The air-fuel mixture flowing into the ignition chamber is ignited by a spark plug and burned, and a flame formed by the combustion is ejected to the combustion chamber through the communication hole. As described above, in the conventional engine, the inflow of the air-fuel mixture from the combustion chamber to the ignition chamber and the ejection of the flame from the ignition chamber to the combustion chamber are performed through one or more communication holes, so that the mixture sucked into the combustion chamber is mixed. The gas is burned (see, for example, Patent Documents 1 and 2).

JP-A 51-55813 JP 2006-177248 A

  In the engine as described above, by spark-igniting the spark plug at a desired ignition timing, the air-fuel mixture flowing into the ignition chamber through the communication hole is burned, and the flame formed by the combustion is passed through the communication hole to the combustion chamber. The mixture in the combustion chamber is burned by jetting. However, since the ignition plug is mounted on the cylinder head so that the plug cover protrudes into the combustion chamber, depending on the operating conditions of the engine, the temperature of the plug cover itself, electrodes, etc. becomes high, and before the desired ignition timing. There is a case where a phenomenon occurs in which the air-fuel mixture self-ignites at a location where the temperature becomes high (hereinafter, this phenomenon is abbreviated as pre-ignition). Thus, when premature ignition occurs, the pressure in the engine cylinder rises abnormally, which may lead to engine damage.

  The present invention has been made paying attention to such a point, and its purpose is to detect a phenomenon that may lead to premature ignition, and to perform premature ignition by performing an appropriate process in accordance with the detection. It is an object of the present invention to provide an engine operating method, an engine, and a spark plug provided in the engine that can prevent the occurrence of the engine and prevent the engine from being damaged.

In order to achieve this object, an engine operating method according to the present invention includes:
An ignition plug in which an ignition chamber is formed in a plug cover that covers an ignition point is attached to a cylinder head, and a communication hole that connects the ignition chamber and a combustion chamber facing a piston is provided in the plug cover. Driving method,
The spark plug, and mounted with said ignition chamber and the combustion chamber from the cylinder head side is protruded to the plug cover to the combustion chamber in the cylinder head so as to communicate with the communication hole, the plug cover or based on the physical quantity corresponding to the heat load on the spark chamber of the electrode, the thermal load on the plug cover or the electrode is determined to be in an overload condition to be overloaded, reduce the thermal load on the plug cover or the electrode Change the operating conditions of the engine to
The physical quantity corresponding to the thermal load on the plug cover or the electrode includes the temperature of the plug cover, the temperature of the electrode, the amount of change in the discharge voltage of the electrode, the pressure in the ignition chamber, and the high frequency of the pressure in the ignition chamber. One of the component amplitudes,
As a change in operating conditions of the plug cover or engine to the side to reduce the heat load on the electrodes, the process for changing the output of the engine only decrease side predetermined output amount or the ignition timing of the engine for a predetermined time After performing any one of the processes to be changed to the delay side, if the overload state is determined, the process for changing the engine output further to the lower side by a predetermined output amount, or the engine ignition The point is that processing is performed to further change the timing to the delay side for a predetermined time.

As described above, since the ignition plug is attached to the cylinder head so that the plug cover protrudes into the combustion chamber, depending on the operating conditions of the engine, an overload state in which the thermal load on the plug cover or electrode of the ignition plug is overloaded. Thus, when the overload state is continued, the temperature of the plug cover itself, the electrode, etc. is increased, and pre-ignition may occur. Therefore, in the engine operating method according to the present invention, as a phenomenon that may lead to premature ignition, it is determined whether or not an overload state in which the thermal load on the plug cover or the electrode is overloaded, and the overload state is determined. By changing the engine operating condition to the side that reduces the thermal load on the plug cover or electrode in accordance with the determination that it is in the load state, the thermal load on the plug cover or electrode is reduced and the overload state is continued. Can be prevented. Therefore, it is possible to prevent the plug cover itself, the electrode, and the like from becoming high temperature, and it is possible to prevent premature ignition.
In this way, the overload state is determined as a phenomenon that may lead to premature ignition, and the engine operation is reduced to the side that reduces the thermal load on the plug cover or electrode in accordance with the determination of the overload state. By changing the conditions, it is possible to perform appropriate processing to prevent premature ignition, prevent premature ignition, and prevent engine damage.

Further , as an operating condition of the engine, for example, by changing the output to the lower side by a predetermined amount or changing the ignition timing to the delay side by a predetermined time, the thermal load on the plug cover or the electrode can be reduced. Even if the operating condition is changed, if it is determined that the engine is overloaded, the engine operating condition is changed again, for example, by changing the output to a lower side by a predetermined amount or by changing the ignition timing to the delay side by a predetermined time. Further, the heat load on the plug cover or the electrode can be reduced. As a result, while determining whether or not the engine is in an overload state, the output can be reduced or the ignition timing can be delayed in stages, and the overload can be performed without excessively reducing the output or delaying the ignition timing. It is possible to accurately prevent the state from continuing.

The operating method of an engine according to the present invention, as a change in operating conditions of the plug cover or engine to the side to reduce the heat load on the electrodes, the process for changing the output of the engine to a predetermined output amount only decrease side, or , After performing either of processes among the processes Ru is changed the ignition timing of the engine to the delayed side by a predetermined period of time, when determining that the not in the overload condition, the thermal load on the plug cover or the electrode It is preferable to restore the engine operating condition to the operating condition before the engine operating condition is changed to the decreasing side.

  That is, by changing the output to the lower side or changing the ignition timing to the delay side to reduce the thermal load on the plug cover or electrode, the thermal load on the plug cover or electrode is reduced when the overload state is resolved. Since the engine operating condition is restored to the operating condition before the engine operating condition is changed to the side to be reduced, the engine is operated under the original appropriate operating condition while preventing the overload state from continuing. be able to.

The characteristic configuration of the engine according to the present invention is as follows.
An engine in which an ignition plug in which an ignition chamber is formed in a plug cover that covers an ignition point is attached to a cylinder head, and a communication hole that connects the ignition chamber and a combustion chamber facing a piston is provided in the plug cover. There,
The spark plug is attached to the cylinder head so that the plug cover protrudes from the cylinder head side into the combustion chamber so that the ignition chamber communicates with the combustion chamber through the communication hole. , the plug cover or heat load detector for detecting a physical quantity corresponding to the heat load is provided for the ignition chamber of the electrode, the plug cover or the electrode on the basis of the physical quantity is the detection information of the heat load detector and overload state discriminating means thermal load is determined whether or not an overload state in which overload for, when determining that an overload condition in said overload state decision section, the thermal load on the plug cover or the electrode Operating condition changing means for performing an operating condition change process for changing the operating condition of the engine on the side to reduce
The thermal load detector that detects a physical quantity corresponding to a thermal load on the plug cover or the electrode includes a temperature of the plug cover, a temperature of the electrode, a change amount of a discharge voltage of the electrode, a pressure in the ignition chamber, and Any of the amplitudes of the high-frequency components of the pressure in the ignition chamber can be detected,
The operating condition changing means may be one of a process for changing the engine output to a lower side by a predetermined output amount or a process for changing the ignition timing of the engine to a delayed side by a predetermined time as the operating condition changing process. After carrying out either of these processes, if the overload state discriminating means discriminates the overload state, the process of changing the engine output further to the lower side by a predetermined output amount, or the ignition timing of the engine again. Furthermore, it is configured to perform a process of changing to the delay side for a predetermined time.

According to this characteristic configuration, as described in the engine operating method according to the present invention described above, an overload state is determined as a phenomenon that may lead to pre-ignition, and the overload state is determined. Accordingly, by changing the operating conditions of the engine to reduce the thermal load on the plug cover or electrode, it is possible to perform appropriate processing to prevent premature ignition and to prevent premature ignition from occurring. Can prevent engine damage. Moreover, in determining whether or not it is an overload state, since the overload state is determined based on the physical quantity corresponding to the thermal load on the plug cover or electrode detected by the thermal load detection unit provided in the spark plug, The overload state can be accurately determined.
In addition, according to this characteristic configuration, as described in the engine operating method according to the present invention described above, the output decrease or the ignition timing delay is stepwise while determining whether or not the engine is overloaded. It is possible to reduce the output or delay the ignition timing step by step, and it is possible to accurately prevent the overload state from continuing without excessively decreasing the output or delaying the ignition timing. .
Further features of the engine according to the present invention are as follows:
The operating condition changing means may be one of a process for changing the engine output to a lower side by a predetermined output amount or a process for changing the ignition timing of the engine to a delayed side by a predetermined time as the operating condition changing process. After performing one of these processes, if it is determined by the overload state determining means that the engine is not in an overload state, an operation condition return process for returning the engine operating condition to the operating condition before performing the operating condition changing process is performed. There is in point to do.
According to this characteristic configuration, the thermal load on the plug cover or the electrode is reduced when the overload state is resolved by performing the operating condition changing process as described in the engine operating method according to the present invention described above. The engine operating condition is restored to the operating condition before the engine operating condition is changed to the operating side, so that the engine is operated under the proper operating condition while preventing the overload state from continuing. Can do.

Further characterizing feature of the engine according to the present invention, the heat load detector, the detected freely configure the electrodes or the temperature of the plug cover of the ignition plug, wherein the overload state judgment means, the thermal load detection When the electrode or the temperature of the plug cover of the ignition plug is detected is equal to or higher than the set temperature in parts, in that the is configured to determine an overload state.

  According to this characteristic configuration, since the temperature of the electrode or plug cover of the spark plug is detected by the thermal load detector, a physical quantity suitable as a physical quantity corresponding to the thermal load on the plug cover or electrode can be detected. Then, the overload state determining means determines that the overload state is detected when the temperature of the plug cover or the electrode of the spark plug detected by the thermal load detection unit exceeds the set temperature. It can be carried out.

According to a further characteristic configuration of the engine according to the present invention, the thermal load detection unit is configured to be able to detect a discharge voltage of the electrode of the spark plug, and the overload state determination unit is configured to be the thermal load detection unit. When the detected change amount of the discharge voltage of the electrode of the spark plug is equal to or greater than a set change amount, the overload state is determined.

  According to this characteristic configuration, since the discharge voltage of the spark plug is detected by the thermal load detector, a physical quantity suitable as a physical quantity corresponding to the thermal load on the plug cover or the electrode can be detected. Then, the overload state determining means determines that the overload state is detected when the change amount of the discharge voltage of the spark plug detected by the thermal load detection unit exceeds the set change amount. It can be carried out.

  A further characteristic configuration of the engine according to the present invention is that the thermal load detection unit is configured to be able to detect a pressure in the ignition chamber, and the overload state determination unit is configured to detect the ignition detected by the thermal load detection unit. It is configured to discriminate from the overload state when the indoor pressure is equal to or higher than a set pressure or when the amplitude of the high-frequency component of the pressure in the ignition chamber detected by the thermal load detector is equal to or higher than a set amplitude. It is in.

  According to this feature configuration, since the pressure in the ignition chamber is detected by the thermal load detector, a physical quantity suitable as a physical quantity corresponding to the thermal load on the plug cover or the electrode can be detected. Then, the overload state determining means detects that the overload is detected when the pressure in the ignition chamber detected by the thermal load detection unit is equal to or higher than the set pressure or the amplitude of the high frequency component of the detected pressure in the ignition chamber is equal to or greater than the set amplitude. Since the state is determined, the overload state can be appropriately determined.

The spark plug according to the present invention is:
A plug body having an ignition point and a plug cover provided on the plug body so as to cover the ignition point, in a state where the plug body and the plug cover are attached to a cylinder head of an engine to be attached, A communication hole for communicating a combustion chamber facing the piston and an ignition chamber formed in the plug cover is formed in the plug cover, and the plug main body and the plug cover are connected to the combustion chamber from the cylinder head side. A plug cover is protruded so that the ignition chamber and the combustion chamber communicate with each other through the communication hole. The engine can be attached to the cylinder head of the engine, and the engine includes the plug cover or an electrode in the ignition chamber. Overload state determining means for determining whether or not the thermal load for the overload is an overload, and the overload state determination When determining that an overload condition at means, and a operating condition changing means for performing the operation condition changing process for changing the operating conditions of the engine on the side to reduce the thermal load on the plug cover or the electrode, the plug body or the the detection target site of the plug cover, said freely detecting a physical quantity corresponding to the thermal load on the plug cover or the electrode, and universal thermal load detector output to the overload state determining means that the detected information Provided,
The thermal load detector that detects a physical quantity corresponding to a thermal load on the plug cover or the electrode includes a temperature of the plug cover, a temperature of the electrode, a change amount of a discharge voltage of the electrode, a pressure in the ignition chamber, and Any of the amplitudes of the high-frequency components of the pressure in the ignition chamber can be detected,
As the operation condition changing process, either one of the process of changing the engine output to the lower side by a predetermined output amount or the process of changing the ignition timing of the engine to the delay side by a predetermined time was performed. After that, when the overload state is determined by the overload state determination means, the process of changing the engine output to a lower side again by a predetermined output amount, or the engine ignition timing is further delayed by a predetermined time. In the point which is used for the engine provided with the operation condition changing means for performing the process of changing to.

According to this characteristic configuration, the physical quantity corresponding to the thermal load on the plug cover or the electrode can be detected in the detection target portion of the plug body or the plug cover, and the detection information is transmitted to the overload state determination unit. Since an outputable thermal load detection unit is provided, by attaching the spark plug including the thermal load detection unit to the engine to be mounted, as described in the engine according to the present invention described above, it is too early. By determining the overload state as a phenomenon that may lead to ignition, and by changing the engine operating condition to the side that reduces the thermal load on the plug cover or electrode in accordance with the determination of the overload state, Appropriate processing for preventing premature ignition can be performed, premature ignition can be prevented from occurring, and engine damage can be prevented. Therefore, the spark plug according to the present invention can provide a suitable spark plug in realizing an engine that can prevent such pre-ignition from occurring.
Further features of the spark plug according to the present invention are as follows:
As the operation condition changing process, either one of the process of changing the engine output to the lower side by a predetermined output amount or the process of changing the ignition timing of the engine to the delay side by a predetermined time was performed. After that, when the overload state determination unit determines that the engine is not in an overload state, the operation condition change unit includes the operation condition change unit that performs a process of returning the engine operation condition to the operation condition before the operation condition change process is performed. It is in the point used for an engine.

Sectional view of the engine according to the present invention The figure which shows the spark plug which concerns on this invention The flowchart which shows operation | movement of the engine in 1st Embodiment. The flowchart which shows operation | movement of the engine in 2nd Embodiment. Sectional drawing of the spark plug in 3rd Embodiment Sectional drawing of the spark plug in 4th Embodiment

An embodiment of an engine according to the present invention will be described with reference to the drawings.
[First Embodiment]
(Entire engine configuration)
As shown in FIG. 1, the engine 1 includes a piston 2, a cylinder 4 that houses the piston 2 and forms a combustion chamber 3 together with the top surface 2 a of the piston 2, and a spark plug 6 that is attached to the cylinder head 5. I have. The piston 2 is reciprocated in the cylinder 4, and the intake valve 7 and the exhaust valve (not shown) are opened and closed to perform the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke in the combustion chamber 3. Do it sequentially. Thereby, although illustration is abbreviate | omitted, it is comprised so that the reciprocating motion of piston 2 may be output as a rotational motion of a crankshaft by a connecting rod. Such a configuration is the same as that of a normal four-stroke internal combustion engine. Here, a four-stroke internal combustion engine will be described as the engine according to the present invention, but a two-stroke internal combustion engine may be employed as the engine according to the present invention.

  The engine 1 uses city gas (13A), which is a gaseous fuel, as the fuel G. In the intake stroke, the intake valve 7 is opened, and the air A and the fuel G are mixed from the intake port 8 to the combustion chamber 3. An air (for example, a lean air-fuel mixture) M is inhaled. In the compression stroke and the expansion stroke, the mixture M taken into the combustion chamber 3 is compressed to burn and expand the fuel. In the exhaust stroke, the exhaust valve (not shown) is opened and exhaust gas is discharged from the combustion chamber 3 to an exhaust port outside the figure.

  A recess 9 is formed in the top surface 2a of the piston 2 facing the cylinder head 5. Thereby, the combustion chamber 3 is constituted by a space formed by the recess 9 in addition to the space between the top surface 2 a of the piston 2 and the inner surface of the cylinder 4. By forming the combustion chamber 3 in this way, when the piston 2 ascends during the compression stroke, a vortex from the periphery of the recess 9 toward the center of the recess 9, that is, a so-called squish is generated.

  The intake port 8 provided in the cylinder head 5 is provided with a fuel supply unit 10 that injects the fuel G with respect to the air A that is taken in. The air-fuel mixture M of the air A and the fuel G (for example, a lean air-fuel mixture) ). By opening the intake valve 7, an air-fuel mixture M of air A and fuel G (for example, a lean air-fuel mixture) is sucked into the combustion chamber 3. Here, the fuel ejection amount from the fuel supply unit 10 can be changed, and the mixing ratio of the air A and the fuel G can be changed according to the operating conditions of the engine 1.

  As shown in FIGS. 1 and 2, the spark plug 6 is opposed to the front end portion (the lower end portion in FIGS. 1 and 2) with the center electrode 11 and the ground electrode 12 spaced apart (discharge gap). A plug body 13 provided in a state of being prepared, and a plug cover 14 provided in the plug body 13 so as to cover the center electrode 11 and the ground electrode 12, and an ignition chamber 15 and a plug cover 14 formed in the plug cover 14. A communication hole 16 that communicates with the outside of the plug cover 14 is formed in the plug cover 14. The center electrode 11 is formed in a columnar shape, for example, and is provided at the tip end portion (the end portion on the lower side in FIGS. 1 and 2) of the plug body 13. The ground electrode 12 is formed in a disk shape, for example, and is disposed at the distal end portion of the extending support 17 that extends downward from the distal end portion of the plug body 13 and then bends and extends in the horizontal direction. Here, an ignition point is formed between the center electrode 11 and the ground electrode 12, and a plug cover 14 is provided on the plug body 13 so as to cover the ignition point.

  The spark plug 6 is attached to the cylinder head 5 with a plug cover 14 protruding from the cylinder head 5 side to the combustion chamber 3 side. The spark plug 6 is mounted so that the plug cover 14 protrudes into the recess 9 formed in the piston 2 at a preset desired ignition timing (for example, timing when the piston 2 is positioned immediately before top dead center). ing. The spark plug 6 is provided so that its central axis is coaxial with the central axis of the combustion chamber 3. Here, the axial direction of the combustion chamber 3 is a direction along the central axis of the combustion chamber 3, for example, the same direction as the vertical movement direction of the piston 2.

  The spark plug 6 is mounted by being inserted into a through-hole 18 formed in the cylinder head 5 along the vertical direction, and the plug cover 14 projects into the combustion chamber 3 in the mounted state. In a state where the plug cover 14 protrudes into the combustion chamber 3 by screwing the screw portion formed on the inner wall portion of the through portion 18 and the screw portion formed on the outer peripheral portion of the spark plug 6 (plug cover 14). A spark plug 6 is attached to the cylinder head 5.

  The plug cover 14 is formed in a bottomed cylindrical shape whose bottom is the tip side (the lower end in FIGS. 1 and 2). The bottom of the plug cover 14 is formed in an arc shape, and an ignition chamber 15 having a center electrode 11 and a ground electrode 12 is formed in the plug cover 14.

  The plug cover 14 is formed with a plurality of communication holes 16 that allow the combustion chamber 3 and the ignition chamber 15 to communicate with each other. The plurality of communication holes 16 are spaced at regular intervals on the circumference centered on the tip position of the plug cover 14 on the central axis of the combustion chamber 3 in the axial direction (vertical direction in FIGS. 1 and 2). A plurality (for example, four) are provided with a gap therebetween.

  The spark plug 6 sparks and burns the air-fuel mixture M flowing into the ignition chamber 15 from the combustion chamber 3 through the communication hole 16, and jets the flame formed by the combustion into the combustion chamber 3 through the communication hole 16. It is configured. In this way, the inflow of the air-fuel mixture M from the combustion chamber 3 to the ignition chamber 15 and the ejection of flame from the ignition chamber 15 to the combustion chamber 3 are performed by the plurality of communication holes 16, so that the combustion chamber 3 is inhaled. The air-fuel mixture M is burned. Therefore, the air-fuel mixture M flowing into the ignition chamber 15 is all the air-fuel mixture M flowing from the combustion chamber 3 through the communication hole 16, and fuel and air-fuel mixture are supplied to the ignition chamber 15 from other than the combustion chamber 3. Never happen.

(Engine operation)
The engine 1 performs an intake stroke in which the air-fuel mixture M is taken into the combustion chamber 3 by the piston 2 descending from the top dead center while the intake valve 7 is opened. Next, the piston 2 ascends in a state where the intake valve 7 is closed, whereby a compression stroke for compressing the air-fuel mixture M in the combustion chamber 3 is performed. In this compression stroke, the volume of the combustion chamber 3 is reduced by the piston 2 rising, so that the air-fuel mixture M in the combustion chamber 3 flows into the ignition chamber 15 through the communication hole 16.
The engine 1 operates the spark plug 6 at a preset desired ignition timing (for example, immediately before the top dead center), sparks the center electrode 11 and the ground electrode 12, and mixes the ignition chamber 15. I want to ignite Qi M. Then, combustion in the ignition chamber 15 proceeds, and a flame is ejected to the combustion chamber 3 through the communication hole 16. Thereby, the air-fuel mixture M in the combustion chamber 3 is combusted and an expansion stroke is performed. Next, when the piston 2 moves up with the exhaust valve opened, an exhaust stroke is performed in which the exhaust gas in the combustion chamber 3 is exhausted to the exhaust port.
In this way, the engine 1 is configured to repeatedly perform a series of operations for performing each stroke in the order of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke.

Hereinafter, a unique configuration of the engine 1 according to the present invention will be described.
In the engine 1 configured as described above, depending on the operating conditions of the engine, the thermal load on the plug cover 14 or the electrodes 11, 12 of the spark plug 6 becomes overloaded, and the plug cover 14 itself, the center electrode 11, and the ground electrode There is a case where a phenomenon occurs in which the air-fuel mixture self-ignites at a location where the temperature of the electrode 12 becomes high before the desired ignition timing (hereinafter, this phenomenon is abbreviated as premature ignition). .

  Therefore, in the engine 1 according to the present invention, as shown in FIG. 1, an overload state determining means 20 for determining an overload state in which the thermal load on the plug cover 14 or the electrodes 11 and 12 is overloaded, and the overload When the state determining unit 20 determines that the overload state is present, the operating condition changing unit 21 that performs an operating condition changing process for changing the operating condition of the engine 1 to the side that reduces the thermal load on the plug cover 14 or the electrodes 11 and 12 is provided. Is provided. The overload state determination unit 20 and the operation condition change unit 21 are provided in the operation control unit 19 that controls the operation of the engine 1.

  As a result, when the overload state discriminating means 20 discriminates that the thermal load on the plug cover 14 or the electrodes 11, 12 is an overload state, the operating condition changing means 21 is applied to the plug cover 14 or the electrodes 11, 12. Since the operating condition of the engine 1 is changed to reduce the thermal load, the thermal load on the plug cover 14 or the electrodes 11 and 12 can be reduced to prevent the overload state from continuing. As a result, it is possible to prevent the temperatures of the plug cover 14 itself of the spark plug 6 and the electrodes of the center electrode 11 and the ground electrode 12 from becoming high, and it is possible to prevent premature ignition.

  In order to determine the overload state by the overload state determination means 20, the spark plug 6 detects a physical quantity corresponding to the thermal load on the plug cover 14 or the electrodes 11, 12 as shown in FIGS. There is provided a thermal load detector 22 that can freely output the detection information to the overload state determination means 20. Here, FIG. 2A shows a cross-sectional view of the spark plug 6, and FIG. 2B shows a plan view of the spark plug 6 as viewed from below. Then, the tip end portion (the end portion on the lower side in FIG. 2) of the plug cover 14 which is the end portion of the portion protruding from the combustion chamber 3 in the plug cover 14 is a detection target portion, and the thermal load detection portion 22 is The thermocouple is configured to detect the temperature of the tip end portion (the lower end portion in FIG. 2) of the plug cover 14 that is the detection target portion. Thus, the spark plug 6 according to the present invention is a spark plug that can be mounted on the engine 1 including the overload state determination means 20 and the operating condition change means 21, and the thermal load detection unit 22 is provided on the plug cover 14. It is provided in the detection target part. The thermal load detection unit 22 detects the temperature of the plug cover 14 as a physical quantity corresponding to the thermal load on the plug cover 14 or the electrodes 11 and 12.

  The overload state determination means 20 is configured to determine an overload state when the temperature of the plug cover 14 detected by the thermal load detection unit 22 is equal to or higher than a set temperature (for example, 850 ° C.). And the operating condition change means 21 performs the process which changes the output of the engine 1 to the predetermined amount fall side as an operating condition change process.

Hereinafter, detection of an overload state by the overload state determination unit 20 and operation condition change processing by the operation condition change unit 21 will be described based on the flowchart of FIG.
When the operation of the engine 1 is started, the operation control unit 19 controls the operation of the engine 1 so that the output of the engine 1 is 100%. Thus, in a state where the engine 1 is operated with the output of the engine 1 being 100%, first, the overload state determination unit 20 detects the temperature of the plug cover 14 from the detection information of the thermal load detection unit 22, It is determined whether or not it is an overload state based on whether or not the detected temperature of the plug cover 14 is equal to or higher than a set temperature (steps # 1 and # 2).

  When the temperature of the plug cover 14 is equal to or higher than the set temperature and the overload state determining unit 20 determines that the overload state is present, the operating condition changing unit 21 reduces the output of the engine 1 by a predetermined amount (for example, 20%). The operation condition changing process is changed to 100%, and the output of the engine 1 is changed from 100% to 80% (step # 3).

When a predetermined time (for example, 10 minutes) elapses after the output of the engine 1 is changed to 80%, the overload state determination unit 20 determines the temperature of the plug cover 14 at that time from the detection information of the thermal load detection unit 22. It is detected, and it is determined whether or not it is an overload state depending on whether or not the detected temperature of the plug cover 14 is equal to or higher than a set temperature (steps # 4 and # 5).
When the temperature of the plug cover 14 is equal to or higher than the set temperature and the overload state determining unit 20 determines that the overload state is present, the operating condition changing unit 21 reduces the output of the engine 1 by a predetermined amount (for example, 20%). The operation condition change process to be changed is performed, and the output of the engine 1 is changed from 80% to 60% (step # 6).

  When a predetermined time elapses after the output of the engine 1 is changed to 60%, the overload state determination means 20 detects the temperature of the plug cover 14 at that time from the detection information of the thermal load detection unit 22, and It is determined whether or not an overload condition is present depending on whether or not the detected temperature of the plug cover 14 is equal to or higher than a set temperature (steps # 7 and # 8). When the overload state discriminating means 20 discriminates the overload state, the operating condition changing means 21 performs an operating condition changing process for changing the output of the engine 1 to a predetermined amount (for example, 20%) lower side, and the engine 1 Is changed from 60% to 40% (step # 9).

  Further, when a predetermined time has elapsed after the output of the engine 1 is changed to 40%, the overload state determination means 20 detects the temperature of the plug cover 14 at that time from the detection information of the thermal load detection unit 22, and Whether or not an overload condition is present is determined based on whether or not the detected temperature of the plug cover 14 is equal to or higher than a set temperature (steps # 10 and # 11). When the load state determination unit 20 determines that the engine is overloaded, the operation condition change unit 21 performs an operation condition change process in which the operation condition change unit 21 stops the operation of the engine 1 to stop the operation of the engine 1. (Step # 12).

In this way, the operating condition changing means 21 performs a process of changing the output of the engine 1 to a predetermined amount lowering side as the operating condition changing process, and after performing the operating condition changing process, the overload state determining means 20 If it is determined that an overload condition is detected, the operating condition change process is performed again. Therefore, as the overload state is determined, the output of the engine 1 can be changed to a lower side step by step by a predetermined amount (for example, 20%). As a result, the output of the engine 1 is gradually changed to the lower side, and the overload state is prevented from continuing without excessively changing the output of the engine 1 to the lower side. It can be prevented in advance.
Even if the output of the engine 1 is changed to 40%, if it is determined that the engine is overloaded, even if the output of the engine 1 is changed to the lower side, the overload state cannot be resolved. By stopping, it is possible to appropriately prevent the overload state from continuing and to prevent the occurrence of premature ignition accurately.

  On the other hand, when the temperature of the plug cover 14 is lower than the set temperature in steps # 5, # 8, and # 11 and the overload state determination unit 20 determines that it is not in the overload state, the operation condition change unit 21 performs the operation condition change. An operation condition return process for returning the operation condition of the engine 1 to the operation condition before the change process is performed is performed, and the output of the engine 1 is returned to 100% (step # 13). Thus, when the engine is not in an overload state, the output of the engine 1 is returned to 100%, so that the engine 1 is operated under appropriate operating conditions without inadvertently changing the output of the engine 1 to the lower side. be able to.

As described above, in the engine operating method according to the present invention, when it is determined that the thermal load on the plug cover 14 or the electrodes 11 and 12 is an overload state, the output of the engine 1 is changed to a predetermined amount lowering side. Then, the operating condition of the engine is changed to reduce the thermal load on the plug cover 14 or the electrodes 11 and 12. In the engine operating method according to the present invention, the output is changed to a predetermined amount lowering side, and the operating condition of the engine 1 is changed to the side where the thermal load on the plug cover 14 or the electrodes 11 and 12 is reduced. When it is determined that the engine is overloaded, the output is changed again to a predetermined amount lower side, and the engine operating condition is changed to the side where the thermal load on the plug cover 14 or the electrodes 11 and 12 is reduced. The operating conditions are repeatedly changed in accordance with the determination of the load state . Further, in the operating method of an engine according to the present invention, not only changes the in operating condition with the determination of the overload condition, when determining that it is not the overload state, the thermal load on the plug cover 14 or the electrodes 11, 12 The operating condition of the engine is returned to the operating condition before the operating condition of the engine 1 is changed to the side of decreasing the engine.

[Second Embodiment]
This 2nd Embodiment shows another embodiment about the processing content of the operating condition change process which the operating condition change means 21 performs in the said 1st Embodiment. Hereinafter, based on the flowchart of FIG. 4, the processing content of the driving condition changing process performed by the driving condition changing means 21 in the second embodiment will be described, but the other configuration is the same as that of the first embodiment. The description is omitted.

  That is, in the first embodiment, as the operating condition changing process, a process of changing the output of the engine 1 to a predetermined amount (for example, 20%) lowering side is performed. In the second embodiment, as the operating condition changing process, a process of changing the ignition timing for operating the spark plug 6 to a delay side for a predetermined time (for example, a time corresponding to 2 deg in the rotation angle of the crankshaft of the engine 1) is performed.

  As shown in FIG. 4, first, the overload state determination unit 20 detects the temperature of the plug cover 14 from the detection information of the thermal load detection unit 22, and whether the detected temperature of the plug cover 14 is equal to or higher than a set temperature. Whether or not it is an overload state is determined based on whether or not (steps # 101 and # 102).

  When the temperature of the plug cover 14 is equal to or higher than the set temperature and the overload state determining unit 20 determines that the overload state is present, the operating condition changing unit 21 sets the ignition timing for operating the spark plug 6 for a predetermined time (for example, engine The operation condition changing process is performed to change the engine 1 to the delay side (time corresponding to 2 deg at the rotation angle of the crankshaft 1), and the ignition timing of the engine 1 is changed from a preset ignition timing (for example, immediately before top dead center) to the engine 1 The crankshaft rotation angle is changed to the time delay side corresponding to 2 deg (step # 103).

After a predetermined time (for example, 10 minutes) has elapsed after the ignition timing of the engine 1 is changed to the time delay side corresponding to 2 deg in terms of the rotation angle of the crankshaft of the engine 1, the overload state determination means 20 detects the thermal load. The temperature of the plug cover 14 at that time is detected from the detection information of the unit 22, and it is determined whether or not it is an overload state depending on whether or not the detected temperature of the plug cover 14 is equal to or higher than the set temperature (step) # 104, # 105).
When the temperature of the plug cover 14 is equal to or higher than the set temperature and the overload state determining unit 20 determines that the overload state is present, the operating condition changing unit 21 sets the ignition timing for operating the spark plug 6 for a predetermined time (for example, engine The operation condition changing process is performed to change the engine 1 to the delay side (time corresponding to 2 deg at the rotation angle of the crankshaft 1), and the ignition timing of the engine 1 is changed from a preset ignition timing (for example, immediately before top dead center) to the engine 1 The rotation angle of the crankshaft is changed to a time delay side corresponding to 4 deg (step # 106).

  Further, when a predetermined time has elapsed after the ignition timing of the engine 1 is changed to the time delay side corresponding to 4 deg in terms of the rotation angle of the crankshaft of the engine 1, the overload state determination means 20 detects the thermal load detection unit 22 The temperature of the plug cover 14 at that time is detected from the information, and it is determined whether or not it is an overload state depending on whether or not the detected temperature of the plug cover 14 is equal to or higher than a set temperature (steps # 107, #). 108). When the overload state determining unit 20 determines that the engine is overloaded, the operation condition changing unit 21 performs an operation condition changing process for stopping the operation of the engine 1 and stops the operation of the engine 1 (step # 109).

In this way, the operating condition changing unit 21 changes the ignition timing of the engine 1 to a delay side for a predetermined time (for example, a time corresponding to 2 deg in the rotation angle of the crankshaft of the engine 1) as the operating condition changing process. If the overload state discriminating means 20 determines that the engine is overloaded, the operation condition change process is performed again. The ignition timing is changed to the delay side step by step by a predetermined time (for example, a time corresponding to 2 degrees in the rotation angle of the crankshaft of the engine 1). As a result, the ignition timing of the engine 1 is gradually changed to the delay side, so that the overload state is prevented from continuing without excessively changing the ignition timing of the engine 1 to the delay side. Occurrence can be prevented in advance.
Even if the ignition timing of the engine 1 is changed from a preset ignition timing (for example, immediately before top dead center) to a time delay side corresponding to 4 deg. If it is determined that the engine is in a load state, even if the ignition timing of the engine 1 is changed to the delay side, it is determined that the overload state cannot be resolved. Therefore, it is possible to prevent the occurrence of premature ignition accurately.

  On the other hand, when the temperature of the plug cover 14 is less than the set temperature in steps # 105 and # 108, and the overload state determination unit 20 determines that it is not in the overload state, the operation condition change unit 21 performs the operation condition change process. An operating condition return process for returning the operating condition of the engine 1 to the operating condition before performing is performed, and the ignition timing of the engine 1 is returned to a preset ignition timing (for example, immediately before top dead center) (step # 110). . As a result, when the engine 1 is not in an overload state, the ignition timing of the engine 1 is returned to operate the engine 1 under appropriate operating conditions without inadvertently changing the ignition timing of the engine 1 to the delay side. Can do.

[Third Embodiment]
This 3rd Embodiment shows another embodiment about the detection target site | part which detects temperature in the thermal load detection part 22 in the said 1st Embodiment. Hereinafter, although the detection target site | part which detects temperature in the thermal load detection part 22 in this 3rd Embodiment is demonstrated, since it is the same as that of the said 1st Embodiment about the other structure, the description is abbreviate | omitted.

  That is, in the first embodiment, as shown in FIG. 2, the detection target portion of the thermal load detection unit 22 is the tip end portion (the lower end portion in FIG. 2) of the plug cover 14, and The temperature of the tip (the lower end in FIG. 2) is detected. Instead of this configuration, as shown in FIG. 5, in the second embodiment, the detection target part of the thermal load detector 23 is detected. Is the ground electrode 12 of the plug body 13, and the thermal load detector 23 is constituted by a thermocouple that detects the temperature of the ground electrode 12.

[Fourth Embodiment]
This 4th Embodiment shows another embodiment about the structure of the thermal load detection part 22 in the said 1st Embodiment. Hereinafter, although the structure of the thermal load detection part in this 4th Embodiment is demonstrated, since it is the same as that of the said 1st Embodiment about the other structure, the description is abbreviate | omitted.

  That is, in the said 1st Embodiment, as shown in FIG. 2, the thermal load detection part 22 is comprised with the thermocouple which detects the temperature of the front-end | tip part (lower edge part in FIG. 2) of the plug cover 14. As shown in FIG. However, instead of this configuration, as shown in FIG. 6, in the fourth embodiment, the thermal load detection unit 24 is configured by a pressure sensor that detects the pressure in the ignition chamber 15. The thermal load detector 14 is built in the plug body 13 with the end portion (lower end portion in FIG. 6) in contact with the ignition chamber 15 of the plug body 13 as a detection target portion.

  And in this 4th Embodiment, unlike the said 1st Embodiment, since the pressure in the ignition chamber 15 is detected in the thermal load detection part 24, the overload state determination means 20 is also the said 1st. Unlike the embodiment, when the pressure in the ignition chamber 15 is equal to or higher than a set pressure (for example, 15 Mpa), the overload state is determined. Here, the overload state determination unit 20 acquires the pressure value in the ignition chamber 15 from the detection information of the thermal load detection unit 14. For example, the engine 1 is in the order of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke. A series of operations for performing each stroke is defined as one cycle, and an average value of pressure values in the ignition chamber 15 for 200 cycles is obtained. Is configured to do.

With respect to the detection of the overload state by the overload state determination unit 20 and the operation condition change process by the operation condition change unit 21 in the fourth embodiment, only part of the processing contents in the flowchart of FIG. 3 is changed. Therefore, only the part to be changed will be described.
That is, in steps # 1, # 4, # 7, and # 10, the process of detecting the temperature of the plug cover 14 based on the detection information of the thermal load detection unit 22 is ignited based on the detection information of the overload detection unit 24. It changes to the process which detects the pressure in the chamber 15. FIG. Further, in steps # 2, # 5, # 8, and # 11, processing for determining whether or not the overload state is present depending on whether or not the temperature of the plug cover 14 is equal to or higher than the set temperature is performed in the ignition chamber 15. It changes to the process which discriminate | determines whether it is an overload state by whether a pressure is more than preset pressure.

Also in the second embodiment, similar to the above, it can be implemented by changing some of the processing contents in the flowchart of FIG.
That is, in steps # 101, # 104, and # 107, the process of detecting the temperature of the plug cover 14 based on the detection information of the thermal load detection unit 22 is performed in the ignition chamber 15 based on the detection information of the overload detection unit 24. Change the process to detect the pressure. In steps # 102, # 105, and # 108, the pressure in the ignition chamber 15 is set to determine whether the plug cover 14 is in an overload state based on whether or not the temperature of the plug cover 14 is equal to or higher than the set temperature. It changes to the process which discriminate | determines whether it is an overload state by whether it is more than a pressure.

[Fifth Embodiment]
This 5th Embodiment shows another embodiment about the structure of the thermal load detection part 22 in the said 1st Embodiment. Hereinafter, although the structure of the thermal load detection part in this 4th Embodiment is demonstrated, since it is the same as that of the said 1st Embodiment about the other structure, the description is abbreviate | omitted.

That is, in the said 1st Embodiment, as shown in FIG. 2, the thermal load detection part 22 is comprised with the thermocouple which detects the temperature of the front-end | tip part (lower edge part in FIG. 2) of the plug cover 14. As shown in FIG. However, as in the fourth embodiment, the thermal load detection unit can be configured by a pressure sensor, and the configuration of the thermal load detection unit is not limited to the thermocouple.
Therefore, in the fifth embodiment, a case where another sensor is applied as the thermal load detection unit is illustrated. For example, the thermal load detection unit can be configured by a sensor that detects a discharge voltage between the center electrode 11 and the ground electrode 12 of the spark plug 6, and the sensor can be provided in the plug body 13 .

  When the thermal load detection unit is configured as a sensor that detects the discharge voltage of the spark plug 6, the overload state determination unit 20 detects that the amount of change in the discharge voltage of the spark plug 6 exceeds the set change amount. It is comprised so that it may discriminate | determine from a load state. Here, the overload state determination means 20 acquires the discharge voltage of the spark plug 6 from the detection information of the thermal load detection unit. For example, the engine 1 performs each stroke in the order of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke. The average value of the discharge voltage of the spark plug 6 of 200 cycles is obtained as a series of operations for performing the above, and when the amount of change of the obtained average value is equal to or greater than a set change amount (for example, 10%), It is configured to determine.

[Another embodiment]
(1) In the fourth embodiment, the overload state determination unit 20 is configured to determine an overload state when the pressure in the ignition chamber 15 is equal to or higher than a set pressure (for example, 15 Mpa). For example, the overload state discriminating means 20 can be configured to discriminate an overload state when the amplitude of the high frequency component of the pressure in the ignition chamber 15 is equal to or greater than the set amplitude.

  According to the present invention, an ignition plug having an ignition chamber formed in a plug cover that covers an ignition point is attached to a cylinder head, and a communication hole that connects the ignition chamber and a combustion chamber facing a piston is provided in the plug cover. By detecting a phenomenon that may lead to premature ignition and performing an operation to prevent premature ignition, premature ignition can be prevented and engine damage can be prevented. The present invention is applicable to an engine operation method, an engine, and a spark plug provided in the engine.

DESCRIPTION OF SYMBOLS 1 Engine 2 Piston 3 Combustion chamber 5 Cylinder head 6 Spark plug 13 Plug main body 14 Plug cover 15 Ignition chamber 16 Communication hole 20 Overload state determination means 21 Operating condition change means 22 Thermal load detection part 23 Thermal load detection part 24 Thermal load detection Part

Claims (9)

An ignition plug in which an ignition chamber is formed in a plug cover that covers an ignition point is attached to a cylinder head, and a communication hole that connects the ignition chamber and a combustion chamber facing a piston is provided in the plug cover. Driving method,
The spark plug, and mounted with said ignition chamber and the combustion chamber from the cylinder head side is protruded to the plug cover to the combustion chamber in the cylinder head so as to communicate with the communication hole, the plug cover or based on the physical quantity corresponding to the heat load on the spark chamber of the electrode, the thermal load on the plug cover or the electrode is determined to be in an overload condition to be overloaded, reduce the thermal load on the plug cover or the electrode Change the operating conditions of the engine to
The physical quantity corresponding to the thermal load on the plug cover or the electrode includes the temperature of the plug cover, the temperature of the electrode, the amount of change in the discharge voltage of the electrode, the pressure in the ignition chamber, and the high frequency of the pressure in the ignition chamber. One of the component amplitudes,
As a change in operating conditions of the plug cover or engine to the side to reduce the heat load on the electrodes, the process for changing the output of the engine only decrease side predetermined output amount or the ignition timing of the engine for a predetermined time After performing any one of the processes to be changed to the delay side, if the overload state is determined, the process for changing the engine output further to the lower side by a predetermined output amount, or the engine ignition An engine operating method for performing processing for changing the timing further to the delay side for a predetermined time. As a change in operating conditions of the plug cover or engine to the side to reduce the heat load on the electrodes, the process for changing the output of the engine only decrease side predetermined output amount or the ignition timing of the engine for a predetermined time After performing either of the processing of the processing to change the delay side, the over and without the determined at load state, prior to changing the operating conditions of the engine on the side to reduce the thermal load on the plug cover or the electrode The engine operating method according to claim 1, wherein the engine operating condition is restored to the operating condition. An engine in which an ignition plug in which an ignition chamber is formed in a plug cover that covers an ignition point is attached to a cylinder head, and a communication hole that connects the ignition chamber and a combustion chamber facing a piston is provided in the plug cover. There,
The spark plug is attached to the cylinder head so that the plug cover protrudes from the cylinder head side into the combustion chamber so that the ignition chamber communicates with the combustion chamber through the communication hole. , the plug cover or heat load detector for detecting a physical quantity corresponding to the heat load is provided for the ignition chamber of the electrode, the plug cover or the electrode on the basis of the physical quantity is the detection information of the heat load detector and overload state discriminating means thermal load is determined whether or not an overload state in which overload for, when determining that an overload condition in said overload state decision section, the thermal load on the plug cover or the electrode Operating condition changing means for performing an operating condition change process for changing the operating condition of the engine on the side to reduce
The thermal load detector that detects a physical quantity corresponding to a thermal load on the plug cover or the electrode includes a temperature of the plug cover, a temperature of the electrode, a change amount of a discharge voltage of the electrode, a pressure in the ignition chamber, and Any of the amplitudes of the high-frequency components of the pressure in the ignition chamber can be detected,
The operating condition changing means may be one of a process for changing the engine output to a lower side by a predetermined output amount or a process for changing the ignition timing of the engine to a delayed side by a predetermined time as the operating condition changing process. After carrying out either of these processes, if the overload state discriminating means discriminates the overload state, the process of changing the engine output further to the lower side by a predetermined output amount, or the ignition timing of the engine again. Further, an engine configured to perform processing for changing to the delay side for a predetermined time.   The operating condition changing means may be one of a process for changing the engine output to a lower side by a predetermined output amount or a process for changing the ignition timing of the engine to a delayed side by a predetermined time as the operating condition changing process. After performing one of these processes, if it is determined by the overload state determining means that the engine is not in an overload state, an operation condition return process for returning the engine operating condition to the operating condition before performing the operating condition changing process is performed. The engine according to claim 3 to be performed. The thermal load detector, the detected freely configure the electrodes or the temperature of the plug cover of the ignition plug, wherein the overload state decision section, the electrode of the spark plug detected by the thermal load detecting unit or The engine according to claim 3 or 4, wherein when the temperature of the plug cover becomes equal to or higher than a set temperature, the engine is determined as the overload state. The thermal load detection unit is configured to be able to detect a discharge voltage of the electrode of the spark plug, and the overload state determination unit is configured to detect a discharge voltage of the electrode of the spark plug detected by the thermal load detection unit. The engine according to claim 3 or 4, wherein the engine is configured to discriminate from the overload state when a change amount is equal to or greater than a set change amount.   The thermal load detection unit is configured to be able to detect the pressure in the ignition chamber, and the overload state determination unit is configured such that the pressure in the ignition chamber detected by the thermal load detection unit is equal to or higher than a set pressure or the heat The engine according to claim 3 or 4, wherein when the amplitude of a high-frequency component of the pressure in the ignition chamber detected by a load detection unit exceeds a set amplitude, the engine is discriminated from the overload state. A plug body having an ignition point and a plug cover provided on the plug body so as to cover the ignition point, in a state where the plug body and the plug cover are attached to a cylinder head of an engine to be attached, A communication hole for communicating a combustion chamber facing the piston and an ignition chamber formed in the plug cover is formed in the plug cover, and the plug main body and the plug cover are connected to the combustion chamber from the cylinder head side. A plug cover is protruded so that the ignition chamber and the combustion chamber communicate with each other through the communication hole. The engine can be attached to the cylinder head of the engine, and the engine includes the plug cover or an electrode in the ignition chamber. Overload state determining means for determining whether or not the thermal load for the overload is an overload, and the overload state determination When determining that an overload condition at means, and a operating condition changing means for performing the operation condition changing process for changing the operating conditions of the engine on the side to reduce the thermal load on the plug cover or the electrode, the plug body or the the detection target site of the plug cover, said freely detecting a physical quantity corresponding to the thermal load on the plug cover or the electrode, and universal thermal load detector output to the overload state determining means that the detected information Provided,
The thermal load detector that detects a physical quantity corresponding to a thermal load on the plug cover or the electrode includes a temperature of the plug cover, a temperature of the electrode, a change amount of a discharge voltage of the electrode, a pressure in the ignition chamber, and Any of the amplitudes of the high-frequency components of the pressure in the ignition chamber can be detected,
As the operation condition changing process, either one of the process of changing the engine output to the lower side by a predetermined output amount or the process of changing the ignition timing of the engine to the delay side by a predetermined time was performed. After that, when the overload state is determined by the overload state determination means, the process of changing the engine output to a lower side again by a predetermined output amount, or the engine ignition timing is further delayed by a predetermined time. A spark plug used in the engine including the operating condition changing means for performing the process of changing the operating condition.   As the operation condition changing process, either one of the process of changing the engine output to the lower side by a predetermined output amount or the process of changing the ignition timing of the engine to the delay side by a predetermined time was performed. After that, when the overload state determination unit determines that the engine is not in an overload state, the operation condition change unit includes the operation condition change unit that performs a process of returning the engine operation condition to the operation condition before the operation condition change process is performed. The spark plug according to claim 8 used in an engine.

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