JP2023167673A - internal combustion engine - Google Patents

Abstract

To make it possible to more appropriately lubricate mutually sliding component parts of an internal combustion engine.SOLUTION: An internal combustion engine 1 in which component parts mutually slide during operation includes: a water supply device for supplying water to slide surfaces of the component parts; and a control unit for controlling the operation of the internal combustion engine. At least one of the slide surfaces of the component parts is formed from silicon-based ceramics. The control unit controls the operation of the internal combustion engine so that low load/no load operation is performed in which an engine load is limited to not more than a standard load until a prescribed standby period passes after the operation of the internal combustion engine is started, and controls the operation of the internal combustion engine so that normal operation is performed in which an engine load is not limited to not more than a standard load after elapse of the standby period.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to internal combustion engines.

BACKGROUND ART Conventionally, internal combustion engines have been known in which sliding parts of a plurality of members in a combustion chamber are formed of a ceramic material or a ceramic-coated material, and water is used for lubrication in the combustion chamber (Patent Document 1). Patent Document 1 states that by using water for lubrication in this way, the inside of the cylinder can be kept clean, and knocking can be suppressed due to the cooling effect of the water.

In addition, Non-Patent Document 1 states that SiC forms a SiO ₂ layer that is softer than the base materials through a tribochemical reaction to prevent solid contact between the base materials, and further reacts with water to form a softer SiO2 layer. It has been disclosed that it becomes an oxide or hydrate, which functions as a type of lubricant, protecting surfaces and reducing friction.

Japanese Patent Application Publication No. 6-159087

Yoshikazu Kimura, “Lubricating with water” Journal of the Japan Society of Mechanical Engineers, 2005.4, Vol. 108, No. 1037, p17-p19

However, simply using a ceramic material for the sliding parts and supplying water to the sliding parts has not necessarily been able to adequately lubricate the mutually sliding component parts of the internal combustion engine.

In view of the above problems, an object of the present disclosure is to enable more appropriate lubrication between mutually sliding component parts of an internal combustion engine.

The gist of the present disclosure is as follows.

(1) An internal combustion engine in which component parts slide against each other during operation,
a water supply device that supplies water to sliding surfaces between the component parts;
A control device that controls the operation of the internal combustion engine,
At least one of the sliding surfaces of the component parts is formed of silicon-based ceramics,
The control device controls the internal combustion engine so that low-load/no-load operation is performed in which the engine load is limited to a predetermined reference load or less until a predetermined standby period elapses after the internal combustion engine starts operating. and controlling the operation of the internal combustion engine so that normal operation is performed in which the engine load is not limited to below the reference load after the standby period has elapsed.
(2) The internal combustion engine according to (1) above, wherein the waiting period is a period required for the cumulative sliding distance between the sliding surfaces of the component parts to reach a predetermined constant distance.
(3) The internal combustion engine according to (2) above, wherein the standby period is a predetermined constant time.
(4) further comprising a concentration parameter detection device that detects a concentration parameter value that changes depending on the concentration of impurities contained in the water supplied to the sliding surface;
The water supply device repeatedly supplies the water after being supplied to the sliding surface to the sliding surface,
The internal combustion engine according to (1) above, wherein the standby period is a period until the rate of change of the value of the concentration parameter detected by the concentration parameter detection device becomes equal to or less than a predetermined reference value.
(5) The internal combustion engine according to (4) above, wherein the concentration parameter is an electrical resistance of water supplied to the sliding surface.
(6) further comprising a resistance parameter detection device that detects a resistance parameter value that changes depending on the magnitude of sliding resistance between the component parts;
The waiting period is a period until the value of the resistance parameter detected by the resistance parameter detection device reaches a value indicating that the magnitude of the sliding resistance is equal to or less than a predetermined reference value. ).
(7) the internal combustion engine is configured to be driven by a motor;
The internal combustion engine according to (6) above, wherein the resistance parameter is the output of the motor when the internal combustion engine is driven by the motor to a predetermined rotational speed.
(8) The water supply device according to any one of (1) to (7) above includes a filter that removes the silicon-based ceramic powder contained in the water supplied to the sliding surface. Internal combustion engine as described.
(9) further comprising a storage section in which water is stored after being supplied to the sliding surface, and a stirring device that stirs the water stored in the storage section;
The water supply device supplies water stored in the storage section to the sliding surface,
Any one of (1) to (8) above, wherein the control device causes the stirring device to stir the water stored in the storage portion until the standby period elapses after the internal combustion engine starts operating. The internal combustion engine according to one.
(10) The component parts sliding with respect to each other include a cylinder and a piston ring provided on the outer periphery of a piston that reciprocates within the cylinder, according to any one of (1) to (9) above. internal combustion engine.
(11) The water supply device includes a water jet that injects water toward the piston, and a piston passage provided in the piston,
The internal combustion engine according to (10) above, wherein the piston passage is formed such that water injected from the water jet flows into the piston passage and water in the piston passage is supplied to the piston ring. .
(12) The internal combustion engine according to any one of (1) to (11) above, wherein the internal combustion engine is an internal combustion engine that uses hydrogen as fuel.

According to the present disclosure, it is possible to more appropriately lubricate mutually sliding component parts of an internal combustion engine.

FIG. 1 is a schematic cross-sectional side view of an internal combustion engine. FIG. 2 is an enlarged cross-sectional side view of the vicinity of the cylinder of the internal combustion engine. FIG. 3 is a diagram schematically showing the hardware configuration of the vehicle regarding control of the internal combustion engine. FIG. 4 is a diagram showing the time course of the load on the internal combustion engine when the internal combustion engine starts operating. FIG. 5 is a flowchart showing a control routine for controlling the operation of the internal combustion engine. FIG. 6 is a flowchart similar to FIG. 5, showing a control routine for controlling the operation of the internal combustion engine. FIG. 7 is a flowchart similar to FIG. 5, showing a control routine for controlling the operation of the internal combustion engine. FIG. 8 is a schematic cross-sectional side view of an internal combustion engine according to a fourth embodiment. FIG. 9 is a schematic cross-sectional side view of an internal combustion engine according to a fifth embodiment. FIG. 10 is a diagram schematically showing a hardware configuration of a vehicle regarding control of an internal combustion engine according to a fifth embodiment. FIG. 11 is a flowchart similar to FIG. 5, showing a control routine for controlling the operation of the internal combustion engine 1.

Hereinafter, embodiments will be described in detail with reference to the drawings. In addition, in the following description, the same reference number is attached to the same component.

First embodiment <Configuration of internal combustion engine>
First, the configuration of the internal combustion engine according to the first embodiment will be described with reference to FIGS. 1 to 3. The internal combustion engine 1 according to this embodiment is a hydrogen engine in which hydrogen is supplied as fuel into a combustion chamber. Further, in this embodiment, the internal combustion engine 1 is mounted on the vehicle 100. Vehicle 100 is a hybrid vehicle that includes, in addition to internal combustion engine 1, an electric motor for driving vehicle 100. In particular, in this embodiment, the internal combustion engine 1 is mainly used as a generator for generating electric power to be supplied to an electric motor, and the vehicle 100 is mainly driven by the electric motor.

FIG. 1 is a schematic cross-sectional side view of an internal combustion engine 1. FIG. Further, FIG. 2 is an enlarged cross-sectional side view of the cylinder vicinity of the internal combustion engine 1. As shown in FIG. In the following description, the upper side of FIGS. 1 and 2 is the upper side of the internal combustion engine 1, and the lower side of FIGS. 1 and 2 is the lower side of the internal combustion engine 1. However, for example, the top and bottom of FIGS. 1 and 2 do not necessarily have to correspond to the top and bottom of the internal combustion engine 1.

As shown in FIGS. 1 and 2, the internal combustion engine 1 includes a cylinder block 2, a cylinder head 3, a piston 4, a crankcase 5, and a water pan 6. One or more cylinders are formed in the cylinder block 2, and the piston 4 reciprocates up and down within this cylinder. Further, a cylinder head 3 is arranged on the cylinder block 2, and a combustion chamber 7 is defined by the cylinder head 3, the cylinder, and the piston 4.

The cylinder block 2 has a cylinder liner 11 defining each cylinder. The cylinder is thus formed by the inner surface of the cylinder liner 11. The cylinder liner 11 is made of silicon-based ceramics. Specifically, in this embodiment, cylinder liner 11 is formed of silicon carbide (SiC). Note that the cylinder liner 11 may be formed of other silicon-based ceramics such as silicon nitride (Si ₃ N ₄ ). Therefore, in this embodiment, the surface defining the cylinder is formed of silicon-based ceramics.

Note that the cylinder block 2 may not have the cylinder liner 11, and the cylinder block 2 itself may define each cylinder. In this case, the cylinder block 2 is made of silicon-based ceramics. Alternatively, a coating of silicon-based ceramics may be formed on the cylinder liner 11 or the surface of the cylinder block 2 that forms the cylinder. In any case, the surfaces defining the cylinder are formed of silicon-based ceramics.

The cylinder head 3 is arranged on the cylinder block 2 and closes the upper part of the cylinder formed in the cylinder block 2. The cylinder head 3 is provided with a spark plug 12 arranged at the center of the top surface of each combustion chamber 7 and a fuel injection valve 13 arranged at the outer peripheral region of each combustion chamber 7 . The fuel injection valve 13 injects fuel into the combustion chamber 7, and the spark plug 12 ignites the air-fuel mixture formed within the combustion chamber 7.

Further, the cylinder head 3 is formed with an intake port 14 through which intake gas flows, and is provided with an intake valve 15 that opens and closes the intake port 14 . The opening and closing of the intake valve 15 is controlled by an intake variable valve mechanism that can change the opening/closing timing of the intake valve 15 and the lift amount of the intake valve 15. Further, the cylinder head 3 is formed with an exhaust port 16 through which exhaust gas flows, and is provided with an exhaust valve 17 that opens and closes the exhaust port 16. The opening and closing of the exhaust valve 17 is also controlled by a variable exhaust valve mechanism that can change the opening and closing timing of the exhaust valve 17 and the lift amount of the exhaust valve 17. Note that the intake variable valve mechanism and/or the exhaust variable valve mechanism may not be provided. In this case, the opening/closing timing and lift amount of the intake valve 15 and/or the exhaust valve 17 are maintained constant.

As shown in FIG. 2, the piston 4 has a plurality of grooves 21 on its outer periphery, each extending around one circumference. Piston rings 22 are arranged in these grooves 21, respectively. Each piston ring 22 is formed such that its outer surface contacts the inner surface of the cylinder liner 11. In this embodiment, the piston ring 22 is made of silicon-based ceramics. Specifically, piston ring 22 is formed of silicon carbide (SiC). Note that the piston ring 22 may be formed of other silicon-based ceramics such as silicon nitride (Si ₃ N ₄ ). Furthermore, a silicon-based ceramic coating may be formed on the outer surface of the piston ring 22. Therefore, in this embodiment, the outer surface of the piston ring 22 and the inner surface of the cylinder liner 11, which are sliding surfaces that slide relative to each other as the piston 4 reciprocates, are both formed of silicon-based ceramics.

Further, the piston 4 is connected to a crankshaft 24 via a connecting rod 23. The connecting rod 23 is connected to the piston 4 by a piston pin 25 and to the crankshaft 24 by a crank pin 26 so as to convert reciprocating movement of the piston 4 into rotational movement of the crankshaft 24.

The crankcase 5 is arranged below the cylinder block 2 and fixed to the cylinder block 2. The crankcase 5 covers the crankshaft 24 so that the crankshaft 24 is not exposed to the outside.

The water pan 6 is arranged below the crankcase 5 and fixed to the crankcase 5. In this embodiment, water is used to lubricate the sliding surfaces between the components of the internal combustion engine 1. The water pan 6 thus functions as a storage section used to store water used for lubrication. The water used here may be simple water, or may be water to which additives for rust prevention or freezing prevention are added, for example.

Next, with reference to FIGS. 1 and 2, the configuration of a water supply device that supplies water for lubricating the internal combustion engine 1 will be described. The water supply device supplies water stored in the water pan 6 to the sliding surfaces of the constituent parts of the internal combustion engine 1 . In particular, in this embodiment, the water stored in the water pan 6 is supplied between the inner surface of the cylinder (the inner surface of the cylinder liner 11 ) and the outer surface of the piston ring 22 .

As shown in FIGS. 1 and 2, the water supply device includes a strainer 31, a pump 32, a water jet 33, and a piston passage 34 formed in the piston 4. When the pump 32 is driven, water stored in the water pan 6 is sucked through the strainer 31 and is injected from the water jet 33 (see the arrow in FIG. 1). The water injected from the water jet 33 flows into the piston passage 34 formed in the piston 4 (see the arrow in FIG. 2), and flows through the piston passage 34 into the groove 21 in which the piston ring 22 is provided. It is then fed to the piston ring 22, in particular between the piston ring 22 and the cylinder liner 11.

The strainer 31 is a mesh-like filtration device for removing foreign matter mixed into the water stored in the water pan 6, and is arranged so as to be immersed in the water stored in the water pan 6. The strainer 31 communicates with a pump 32, and the water stored in the water pan 6 is supplied to the pump 32 through the strainer 31.

The pump 32 sucks up water stored in the water pan 6 through the strainer 31 and supplies it to the water jet 33. The pump 32 is configured by, for example, an electric variable displacement pump. The pump 32 is connected to an engine ECU 40, which will be described later, and is controlled by instructions from the engine ECU 40.

Water jet 33 is attached to cylinder block 2 or crankcase 5 below each cylinder. The water jet 33 injects water supplied from the pump 32 toward the inside of the piston 4 and the wall surface of each cylinder.

A piston passage 34 formed in the piston 4 supplies water jetted toward the lower surface of the piston 4 by the water jet 33 to the groove 21 in which the piston ring 22 is provided. The piston passage 34 includes an annular main passage (cooling channel) 34a that extends all around the piston 4, an inlet passage 34b that extends from the main passage 34a to the lower surface of the piston 4, and an outlet passage 34c that communicates with each groove 21. has. The inlet passage 34b is located on an extension line of the water jet 33 in the jetting direction. Further, each outlet passage 34c extends radially, and a plurality of outlet passages 34c are provided between each groove 21 and the main passage 34a. Outlet passages 34c between each groove 21 and the main passage 34a are provided at equal intervals in the circumferential direction.

In the piston passage 34 configured in this way, when water is jetted from the water jet 33, the jetted water flows into the inlet passage 34b. The water that has entered the inlet passage 34b flows circumferentially within the main passage 34a, and then flows into the groove 21 through the outlet passage 34c.

Therefore, in this embodiment, some of the water jetted from the water jet 33 is directly supplied onto the inner surface of the cylinder liner 11. Further, some of the water jetted from the water jet 33 is supplied to the groove 21 via the piston passage 34. The water thus supplied onto the inner surface of the cylinder liner 11 and into the groove 21 of the piston 4 then flows between the outer surface of the piston ring 22 and the inner surface of the cylinder liner 11, that is, between the components of the internal combustion engine 1. Supplied onto the sliding surface.

FIG. 3 is a diagram schematically showing the hardware configuration of vehicle 100 regarding control of internal combustion engine 1. As shown in FIG. As shown in FIG. 3, the internal combustion engine 1 includes an engine ECU 40 that functions as a control device that controls the operation of the internal combustion engine 1. In addition, the internal combustion engine 1 includes a concentration sensor 41 and an output sensor 42 as sensors for detecting various parameters related to the internal combustion engine 1. Further, the internal combustion engine 1 includes a throttle valve 43 in addition to the above-described spark plug 12, fuel injection valve 13, and pump 32 as actuators used to control the internal combustion engine 1. Vehicle 100 also includes a power control unit (PCU) 51 that controls the electric motor, and a motor ECU 50 that controls PCU 51. The PCU 51 includes, for example, an inverter, a DC/DC converter, and the like. These concentration sensor 41, output sensor 42, spark plug 12, fuel injection valve 13, pump 32, throttle valve 43, PCU 51, engine ECU 40, and motor ECU 50 are connected to an in-vehicle network 63 compliant with standards such as CAN (Controller Area Network). , are connected to each other.

The concentration sensor 41 is a sensor that detects the concentration of impurities contained in the water stored in the water pan 6. The impurities include, for example, silicon-based ceramic powder generated by scraping the sliding surfaces of the outer surface of the piston ring 22 and the inner surface of the cylinder liner 11 as they slide against each other. In particular, in this embodiment, the concentration sensor 41 detects the electrical resistance of water stored in the water pan 6 in order to detect the concentration of impurities. The higher the electrical resistance detected by the concentration sensor 41, the lower the concentration of impurities contained in the water stored in the water pan 6.

Note that in this embodiment, the concentration sensor 41 detects the electrical resistance of the water stored in the water pan 6 as a concentration parameter that changes depending on the concentration of impurities. However, instead of the concentration sensor 41, a concentration parameter detection device that detects other concentration parameters that change depending on the concentration of impurities contained in the water stored in the water pan 6 may be used. For example, the concentration parameter detection device may detect the transparency of water stored in the water pan 6 in order to detect the concentration of impurities.

The output sensor 42 is a sensor that detects the output of the electric motor. The output sensor 42 detects the output of the electric motor based on the electric power supplied to the electric motor, for example. In particular, when the internal combustion engine 1 is driven by an electric motor without fuel being supplied to the internal combustion engine 1, the output sensor 42 detects the driving resistance of the internal combustion engine 1, that is, the frictional resistance between the component parts of the internal combustion engine 1. be able to.

The throttle valve 43 is provided in the intake passage of the internal combustion engine 1 and controls the flow rate of intake gas supplied to the combustion chamber 7 . Therefore, the throttle valve 43 is used together with the fuel injection valve 13 and the spark plug 12 to control the operation of the internal combustion engine 1. Note that in order to control the operation of the internal combustion engine 1, other devices such as a variable valve mechanism, an EGR valve, etc. may be further used.

Note that the internal combustion engine 1 or the vehicle 100 does not need to have all the components described above. Therefore, the internal combustion engine 1 does not need to have the concentration sensor 41 or the output sensor 42, for example.

Further, in this embodiment, the internal combustion engine 1 is mainly used as a generator, but the internal combustion engine 1 may be used to directly drive the internal combustion engine 1 in addition to generating electricity. Furthermore, in this embodiment, the vehicle 100 equipped with the internal combustion engine 1 is a hybrid vehicle, but the vehicle 100 is a vehicle that is driven only by the internal combustion engine 1 and does not have an electric motor for driving the vehicle 100. There may be.

<Water lubrication>
As described above, in the internal combustion engine 1 according to the present embodiment, the inner surface of the cylinder liner 11 and the outer surface of the piston ring 22 are made of SiC ceramics. Further, when the piston 4 reciprocates within the cylinder, that is, when the piston ring 22 slides on the cylinder liner 11, water is supplied to these sliding surfaces as described above.

Here, when friction occurs in silicon-based ceramics such as SiC in an environment where water is supplied, a chemical reaction expressed by the following formula (1) occurs due to a tribochemical reaction on the sliding surface, and silicon dioxide _SiO2 is produced.
SiC+ _2H2O → _SiO2 + _CH4 ...(1)
The SiO ₂ produced in this way is amorphous and soft, and has a small shearing force. Therefore, when SiO2 is generated on the sliding surface, the frictional resistance during sliding is reduced.

In addition, in an environment where water is supplied, SiO ₂ is converted to hydroxide (Si(OH) ₄ ) as represented by the following formula (2) or hydrated (SiO ₂ .nH ₂ O).
SiO ₂ +2H ₂ O→Si(OH) ₄ …(2)
Si(OH) ₄ and SiO ₂ .nH ₂ O produced in this way function as a lubricant, thereby further reducing frictional resistance during sliding.

Therefore, when the piston 4 reciprocates within the cylinder and the piston ring 22 slides against the cylinder liner 11 in an environment where water is supplied, SiO ₂ is formed on the outer surface of the piston ring 22 and the inner surface of the cylinder liner 11. , Si(OH) ₄ or SiO ₂ .nH ₂ O (hereinafter collectively referred to as "SiO ₂ etc."), and the frictional resistance between them is reduced.

Note that such a phenomenon occurs not only in SiC ceramics but also in other silicon-based ceramics such as Si ₃ N ₄ . Therefore, even if the cylinder liner 11 and the piston ring 22 are formed of silicon-based ceramics other than SiC, the above-described friction reduction effect can be obtained.

Moreover, the above-mentioned phenomenon can occur if at least one sliding surface of the components that slide on each other is formed of silicon-based ceramics. Therefore, as long as at least one sliding surface of the components that slide against each other is formed of silicon-based ceramics, the other sliding surface may be formed of another material. Therefore, if one of the sliding surfaces of the cylinder liner 11 and the piston ring 22 is made of silicon-based ceramics, the other sliding surface may be made of iron, aluminum, or the like.

<Control during startup>
Incidentally, while the internal combustion engine 1 is stopped, almost no SiO ₂ or the like remains on the inner surface of the cylinder liner 11 or the outer surface of the piston ring 22. Therefore, when the internal combustion engine 1 starts operating (when the crankshaft 24 starts rotating from a stopped state), basically there is almost no SiO ₂ etc. left on these sliding surfaces. . Therefore, when the internal combustion engine 1 starts operating, the piston 4 reciprocates within the cylinder, which tends to cause scratches and wear on the inner surface of the cylinder liner 11 and the outer surface of the piston ring 22, and also causes large friction losses. It's easy. In particular, when the load on the internal combustion engine 1 is high and the pressure inside the combustion chamber 7 becomes high, the pressing force of the piston ring 22 against the cylinder liner 11 becomes strong, and the wobbling of the piston 4 due to vibration becomes large. , are particularly susceptible to scratches and wear.

Therefore, in the present embodiment, the internal combustion engine 1 is configured to perform low-load operation in which the load of the internal combustion engine 1 is controlled to be below a predetermined reference load until a predetermined standby period elapses after the internal combustion engine 1 starts operating. The operation of engine 1 is controlled. Thereafter, after a standby period has elapsed since the internal combustion engine 1 started operating, normal operation is performed in which the engine load is not limited to a reference load or less. Here, the reference load means that when the load of the internal combustion engine 1 becomes larger than the reference load, large scratches and wear occur on the inner surface of the cylinder liner 11 and the outer surface of the piston ring 22 immediately after the internal combustion engine 1 starts operating. It's a heavy load. Further, although an upper limit load may be set during normal operation of the internal combustion engine 1, the reference load is a load lower than the upper limit load.

FIG. 4 is a diagram showing the time course of the load on the internal combustion engine 1 when the operation of the internal combustion engine 1 is started.

In the example shown in FIG. 4, the internal combustion engine 1 starts operating (the crankshaft 24 starts rotating) at time t1. When the internal combustion engine 1 starts operating at time t1, the internal combustion engine 1 performs low load operation, and the load of the internal combustion engine 1 is set to the first load L1. The first load L1 is, for example, a minimum load required for the internal combustion engine 1 to operate, and is a load that is equal to or lower than the above-mentioned reference load. The first load L1 is, for example, a load necessary for maintaining the internal combustion engine 1 in an idling state. Therefore, after time t1, the engine ECU 40 controls various actuators of the internal combustion engine 1 (for example, the throttle valve 43, the fuel injection valve 13, the spark plug 12, etc.) so that the load on the internal combustion engine 1 becomes the first load L1. Control.

Once the load of the internal combustion engine 1 is set to the first load, it is maintained over the standby period. Here, the waiting period is a period considered necessary to generate a film of SiO ₂ or the like on the outer surface of the piston ring 22 or the inner surface of the cylinder liner 11 to a sufficient extent to suppress scratches and wear. . Here, in order to form a film of SiO ₂ or the like on the inner surface of the cylinder liner 11 and the outer surface of the piston ring 22, it is necessary that these sliding surfaces slide a certain distance. Therefore, in this embodiment, the standby period is the period required for these sliding surfaces to slide a certain distance. In this embodiment, the waiting period is set to a predetermined constant reference time. After the waiting period has elapsed, it is considered that a film of SiO ₂ or the like has been sufficiently formed on the outer surface of the piston ring 22 or the inner surface of the cylinder liner 11. Therefore, after the standby period has elapsed, there is no longer a need for low-load operation.

Therefore, in this embodiment, as shown in FIG. 4, the internal combustion engine 1 performs normal operation after time t2 when the standby period has elapsed from time t1. The normal operation is an operation performed by the internal combustion engine 1 when the internal combustion engine 1 is not under special conditions such as starting operation. In particular, in this embodiment, since the internal combustion engine 1 is used to generate electric power to be supplied to the electric motor, the internal combustion engine 1 is maintained at a constant load during normal operation so that the internal combustion engine 1 can be operated efficiently. Ru. Therefore, after time t2, the load on the internal combustion engine 1 is set to the second load L2. The second load L2 is, for example, a load set when the internal combustion engine 1 performs normal operation, and is a load larger than the reference load mentioned above. In particular, in this embodiment, the second load is set to a load that allows the internal combustion engine 1 to operate most efficiently. Therefore, after time t2, the engine ECU 40 controls various actuators of the internal combustion engine 1 so that the load on the internal combustion engine 1 becomes the second load L2.

FIG. 5 is a flowchart showing a control routine for controlling the operation of the internal combustion engine 1. As shown in FIG. The illustrated control routine is executed by the engine ECU 40 at regular time intervals.

First, in step S11, the engine ECU 40 determines whether or not the operation of the internal combustion engine 1 has been started (step S11). If it is determined in step S11 that the operation of the internal combustion engine 1 has not started, that is, if the internal combustion engine 1 is stopped, the control routine is ended.

On the other hand, if it is determined in step S11 that the operation of the internal combustion engine 1 has been started, the engine ECU 40 determines that the elapsed time T from the start of the operation of the internal combustion engine 1 is a predetermined reference time. It is determined whether it is Tref (step S12). In step S12, if it is determined that the elapsed time T is less than the reference time Tref, the internal combustion engine 1 performs low load operation, and the load of the internal combustion engine 1 is therefore set to the first load L1 (step S13). On the other hand, if it is determined in step S12 that the elapsed time T is equal to or greater than the reference time Tref, the internal combustion engine 1 is operated normally, and the load of the internal combustion engine 1 is therefore set to the second load L2 (step S14).

<Effects and modifications>
As described above, while the internal combustion engine 1 is stopped, almost no SiO ₂ or the like remains on the inner surface of the cylinder liner 11 or the outer surface of the piston ring 22. Therefore, when the internal combustion engine 1 starts operating, these sliding surfaces do not have sufficient lubrication, and therefore, these sliding surfaces are likely to be scratched or worn.

In contrast, in the present embodiment of the internal combustion engine 1, the internal combustion engine 1 performs low-load operation after the internal combustion engine 1 starts operating until the standby period elapses. Therefore, even when the internal combustion engine 1 starts operating, scratches and wear on the sliding surfaces can be suppressed, and the sliding components of the internal combustion engine 1 can be more appropriately lubricated. be able to. Note that the internal combustion engine 1 may perform a no-load operation in which there is no load until a standby period elapses after the internal combustion engine 1 starts operating. During no-load operation, the internal combustion engine 1 is operated without being supplied with fuel, and the internal combustion engine 1 is driven, for example, by an electric motor (or starter motor).

Furthermore, in this embodiment, the internal combustion engine 1 is a hydrogen engine in which hydrogen is supplied into the combustion chamber 7 as fuel. Therefore, components such as CO ₂ and SO _x are not included in the exhaust gas accompanying the combustion of the fuel. In this embodiment, since oil is not used as a lubricant, the exhaust gas discharged from the internal combustion engine 1 does not contain oil-derived CO ₂ or SO _x . Therefore, according to the internal combustion engine 1 of this embodiment, the amount of emissions of _CO2 , _SOx , etc. can be kept low. Note that the internal combustion engine 1 in this embodiment can appropriately lubricate the mutually sliding component parts even if the internal combustion engine 1 is an internal combustion engine that uses fossil fuel as fuel. It may also be an internal combustion engine.

Note that in the above embodiment, as normal operation, the load of the internal combustion engine 1 is set to a constant second load L2 that is larger than the first load L1. However, during normal operation, the engine may be operated in other manners as long as the engine load is not limited. For example, when the vehicle 100 is driven by the internal combustion engine 1, the vehicle 100 may be driven under a load that corresponds to the amount of depression of the accelerator pedal by the driver during normal driving.

Furthermore, in the embodiment described above, the standby period during which the internal combustion engine 1 performs low-load operation is set to be a fixed reference time. However, the waiting period may be any period other than the fixed time period, as long as it is a period necessary for these sliding surfaces to slide a fixed distance. Therefore, the waiting period may be, for example, a period from when the internal combustion engine 1 starts operating until the sliding surfaces slide a certain distance, or after the internal combustion engine 1 starts operating. It may be a period until the cumulative rotational speed of the crankshaft 24 reaches a certain value. In any case, by setting the standby period based on the elapsed time since the internal combustion engine 1 started operating, the sliding distance, or the cumulative rotation speed, SiO ₂ can be measured relatively accurately without providing an additional sensor. It can be inferred that a film such as the following was produced.

Furthermore, in the embodiment described above, the components of the internal combustion engine 1 that slide against each other are the cylinder liner 11 and the piston ring 22. However, the components of the internal combustion engine 1 that slide against each other, such as the intake valve 15 and the intake cam that opens and closes the intake valve 15, or the exhaust valve 17 and the exhaust cam that opens and closes the exhaust valve, are other than the cylinder liner 11 and the piston ring 22. It may be a component. Also in this case, for example, the sliding surfaces of the intake valve 15 and the intake cam are formed of SiC ceramics, and water is supplied to these sliding surfaces.

Second Embodiment Next, an internal combustion engine 1 according to a second embodiment will be described with reference to FIG. The configurations of the internal combustion engine 1 and the vehicle 100 according to the second embodiment are basically the same as the configurations of the internal combustion engine 1 and the vehicle 100 according to the first embodiment. Below, the description will focus on parts that are different from the internal combustion engine 1 and vehicle 100 according to the first embodiment.

In the first embodiment, the waiting period is the period required for the sliding surfaces to slide a certain distance. On the other hand, in the second embodiment, the waiting period is the value of the concentration parameter that changes depending on the concentration of impurities contained in the water stored in the water pan 6, that is, the water supplied to the sliding surface. This is the period until the rate of change becomes equal to or less than a predetermined reference value.

Here, in this embodiment, the water supplied onto the inner surface of the cylinder liner 11 and the outer surface of the piston ring 22, that is, onto the sliding surface, is returned into the water pan 6. Water in the water pan 6 is then supplied to the sliding surface via the pump 32 and water jet 33. Therefore, in this embodiment, the water that has been supplied to the sliding surface is repeatedly supplied to the sliding surface.

When a film of SiO ₂ or the like is formed on the sliding surface, the sliding surface is sufficiently lubricated, so that there is almost no wear on the sliding surface. On the other hand, if a film of SiO ₂ or the like is not formed on the sliding surface, the sliding surface will not be sufficiently lubricated, resulting in wear. When the sliding surface wears in this way, the amount of powder such as SiC contained in the water stored in the water pan 6 increases. That is, the concentration of impurities contained in the water stored in the water pan 6 increases. Therefore, when the concentration of impurities changes, it is considered that no film such as SiO ₂ is formed on the sliding surface, and conversely, when the concentration of impurities does not change, there is no film such as SiO ₂ formed on the sliding surface. It is thought that a film of Therefore, in this embodiment, when the rate of change in the concentration of impurities is faster than a predetermined reference rate, it is determined that a film such as SiO ₂ is not formed on the sliding surface, and the rate of change in the concentration of impurities is determined to be faster than the predetermined reference rate. When the speed is below the reference speed, it is determined that a film of SiO ₂ or the like is formed on the sliding surface. Thereby, it is possible to accurately detect that a film of SiO ₂ or the like is formed on the sliding surface.

FIG. 6 is a flowchart similar to FIG. 5, showing a control routine for controlling the operation of the internal combustion engine 1. The illustrated control routine is executed by the engine ECU 40 at regular time intervals. Steps S21, S23, and S24 in FIG. 6 are the same as steps S11, S13, and S14 in FIG. 5, respectively, and therefore the description thereof will be omitted.

If it is determined in step S21 that the operation of the internal combustion engine 1 has been started, the engine ECU 40 determines that the rate of change R of the electrical resistance detected by the concentration sensor 41 is less than or equal to a predetermined reference value Rref. It is determined whether or not (step S22). The reference value Rref at this time is, for example, a value corresponding to the reference speed described above.

If it is determined in step S22 that the rate of change in electrical resistance R is faster than the reference value Rref, that is, if it is determined that the rate of change in impurity concentration is faster than the reference rate, the internal combustion engine 1 is operated at low load. is performed (step S23). On the other hand, if it is determined in step S22 that the rate of change in electrical resistance R is equal to or less than the reference value Rref, normal operation is performed in the internal combustion engine 1 (step S24).

In the present embodiment, the operating state of the internal combustion engine 1 is switched between low-load operation and normal operation based on whether the rate of change R of electrical resistance is equal to or lower than the reference value Rref. However, based on the rate of change of other concentration parameters that change depending on the concentration of impurities contained in the water stored in the water pan 6, the operating state of the internal combustion engine 1 can be changed between low-load operation, no-load operation, and normal operation. It may be switched with .

Third Embodiment Next, an internal combustion engine 1 according to a third embodiment will be described with reference to FIG. The configurations of the internal combustion engine 1 and the vehicle 100 according to the third embodiment are basically the same as the configurations of the internal combustion engine 1 and the vehicle 100 according to the first embodiment. Below, the description will focus on parts that are different from the internal combustion engine 1 and vehicle 100 according to the first embodiment.

In the first embodiment, the waiting period is the period required for the sliding surfaces to slide a certain distance. In contrast, in the third embodiment, the standby period is the period until the value of the resistance parameter, which changes depending on the magnitude of the sliding resistance between the components of the internal combustion engine 1, becomes equal to or less than a predetermined reference value. It is said that

Here, unless a film of SiO ₂ or the like is formed on the sliding surfaces of the piston ring 22 and the cylinder liner 11, the sliding resistance between the components will be large. On the other hand, if a film of SiO ₂ or the like is formed on the sliding surfaces of the component parts, the sliding resistance between the component parts is small. Therefore, in this embodiment, when the sliding resistance between the component parts is larger than a predetermined reference resistance, it is determined that a film such as SiO ₂ is not formed on the sliding surface, and the sliding resistance between the component parts is determined to be not formed on the sliding surface. When the resistance is less than a predetermined reference resistance, it is determined that a film of SiO ₂ or the like is formed on the sliding surface. Thereby, it is possible to accurately detect that a film of SiO ₂ or the like is formed on the sliding surface.

Furthermore, in the present embodiment, the internal combustion engine 1 is controlled so that the internal combustion engine 1 is operated in a no-load operation without any load from the start of operation of the internal combustion engine 1 until a standby period has elapsed. During the standby period, the internal combustion engine 1 is therefore driven by the electric motor.

FIG. 7 is a flowchart similar to FIG. 5, showing a control routine for controlling the operation of the internal combustion engine 1. The illustrated control routine is executed by the engine ECU 40 at regular time intervals. Steps S31, S33, and S34 in FIG. 7 are the same as steps S11, S13, and S14 in FIG. 5, respectively, and therefore the description thereof will be omitted.

If it is determined in step S31 that the operation of the internal combustion engine 1 has been started, the engine ECU 40 detects the output sensor when the internal combustion engine 1 is being driven by the electric motor to a predetermined rotational speed. It is determined whether the output W of the electric motor detected by 42 is less than or equal to a predetermined reference value Wref (step S32). Here, the greater the sliding resistance between the inner surface of the cylinder liner 11 and the outer surface of the piston ring 22, the greater the output of the electric motor for operating the internal combustion engine 1 at a predetermined rotational speed. That is, the output of the electric motor for operating the internal combustion engine 1 at a predetermined rotational speed can be said to be a resistance parameter that changes depending on the magnitude of the sliding resistance between the component parts. Therefore, if a film such as SiO ₂ is not formed on these sliding surfaces and the sliding resistance between the sliding surfaces is large, the output of the electric motor detected by the output sensor 42 is large. On the other hand, when a film of SiO ₂ or the like is formed on these sliding surfaces and the sliding resistance between the sliding surfaces decreases, the output of the electric motor detected by the output sensor 42 decreases. The reference value Wref at this time is, for example, a value corresponding to the reference resistance described above.

If it is determined in step S32 that the output W of the electric motor is larger than the reference value Wref, no-load operation is performed in the internal combustion engine 1, and the internal combustion engine 1 is driven by the electric motor (step S33). On the other hand, if it is determined in step S32 that the output W of the electric motor is equal to or less than the reference value Wref, normal operation is performed in the internal combustion engine 1 (step S34).

In this embodiment, the operating state of the internal combustion engine 1 is switched between no-load operation and normal operation based on whether the output W of the electric motor is less than or equal to the reference value Wref. However, the operating state of the internal combustion engine 1 may be switched between no-load operation or low-load operation and normal operation based on other resistance parameters that change depending on the sliding resistance between the component parts of the internal combustion engine 1. .

Fourth Embodiment Next, an internal combustion engine 1 according to a fourth embodiment will be described with reference to FIG. The configurations of the internal combustion engine 1 and the vehicle 100 according to the fourth embodiment are basically the same as the configurations of the internal combustion engine 1 and the vehicle 100 according to the first to third embodiments. Below, the description will focus on parts that are different from the internal combustion engine 1 and vehicle 100 according to the first embodiment to the third embodiment.

FIG. 8 is a schematic cross-sectional side view of the internal combustion engine 1 according to the fourth embodiment. As shown in FIG. 8, in this embodiment, the water supply device supplies water to the inner surface of the cylinder liner 11 and the outer surface of the piston ring 22, that is, to the sliding surfaces of the component parts of the internal combustion engine 1. A filter 36 is provided to remove SiC ceramic powder contained in the water. In particular, in this embodiment, the filter 36 is provided in the water flow path between the strainer 31 and the pump 32.

As mentioned above, when the sliding surfaces of SiC ceramics slide against each other, especially when the lubrication on the sliding surfaces is insufficient, the sliding surfaces are scraped together and the water stored in the water pan 6 is scraped. SiC ceramic powder is mixed in. If water containing large-sized powder among such powders is supplied to the sliding surface, scratches may be formed on the sliding surface. According to this embodiment, since large SiC ceramic powder is removed in the filter 36, it is possible to suppress the formation of scratches on the sliding surface.

Note that in this embodiment, the filter 36 is provided in the water flow path between the strainer 31 and the pump 32, but if it can be removed from the water before it is supplied to the sliding surface, the filter 36 can be may be provided in the flow path.

Fifth Embodiment Next, an internal combustion engine 1 according to a fifth embodiment will be described with reference to FIGS. 9 to 11. The configurations of the internal combustion engine 1 and the vehicle 100 according to the fifth embodiment are basically the same as the configurations of the internal combustion engine 1 and the vehicle 100 according to the first to fourth embodiments. Below, the description will focus on the parts that are different from the internal combustion engine 1 and vehicle 100 according to the first to fourth embodiments.

FIG. 9 is a schematic cross-sectional side view of the internal combustion engine 1 according to the fifth embodiment. Further, FIG. 10 is a diagram schematically showing the hardware configuration of the vehicle 100 regarding control of the internal combustion engine 1 according to the fifth embodiment. As shown in FIGS. 9 and 10, in this embodiment, the internal combustion engine 1 includes a stirring device 37 that stirs water stored in the water pan 6, and a stirring actuator 45 that drives the stirring device 37. , has.

The stirring device 37 is disposed within the water pan 6 and, when driven by the stirring actuator 45, stirs the water stored within the water pan 6. When the water stored in the water pan 6 is stirred, the SiC ceramic powder is uniformly dispersed in the water.

The stirring actuator 45 is connected to the stirring device 37 and drives the stirring device 37 . Further, as shown in FIG. 10, the stirring actuator 45 is connected to the engine ECU 40 via an in-vehicle network 63. Therefore, the stirring device 37 is controlled by the engine ECU 40.

By the way, as described above, when the sliding surfaces of the SiC ceramics slide against each other, the powder of the SiC ceramics gets mixed into the water stored in the water pan 6. When water containing fine SiC ceramic powder is supplied to the sliding surface, this SiC ceramic powder contributes to the reactions of equations (1) and (2) above and the formation of SiO ₂ hydrate. However, SiO ₂ etc. are likely to be formed on the sliding surface. Therefore, in this embodiment, the water stored in the water pan 6 is stirred by the stirring device 37 until a predetermined standby period elapses after the internal combustion engine 1 starts operating. This facilitates the formation of SiO ₂ and the like on the sliding surfaces at an early stage after the internal combustion engine 1 starts operating.

FIG. 11 is a flowchart similar to FIG. 5, showing a control routine for controlling the operation of the internal combustion engine 1. The illustrated control routine is executed by the engine ECU 40 at regular time intervals. Steps S41 to S44 in FIG. 11 are the same as steps S11 to S14 in FIG. 5, respectively, so the explanation will be omitted.

If it is determined in step S42 that the elapsed time T is less than the reference time Tref, the load on the internal combustion engine 1 is set to the first load L1 (step S43), and the stirring device 37 is activated (step S45). Therefore, the water stored in the water pan 6 is stirred, and water containing SiC ceramic powder is supplied to the sliding surface. On the other hand, if it is determined in step S12 that the elapsed time T is equal to or greater than the reference time Tref, the load on the internal combustion engine 1 is set to the second load L2 (step S44), and the stirring device 37 is stopped. . Therefore, the water stored in the water pan 6 is not stirred, and therefore water that does not contain much SiC ceramic powder is supplied to the sliding surface.

In the fifth embodiment, the stirring device is stopped after a predetermined standby period has elapsed after the internal combustion engine 1 started operating. Therefore, power consumption associated with the operation of the stirring actuator 45 can be suppressed. However, the stirring device may continue to be operated even after a predetermined waiting period has elapsed after the internal combustion engine 1 started operating.

Further, in this embodiment as well, a filter may be provided in the water supply device as in the fourth embodiment. In this case, the SiC ceramic powder having a large particle size is removed by the filter. Therefore, SiO ₂ etc. can be formed on the sliding surface at an early stage while suppressing damage to the sliding surface due to large SiC ceramic powder being supplied to the sliding surface.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the claims.

1 Internal combustion engine 2 Cylinder block 3 Cylinder head 4 Piston 6 Water pan 11 Cylinder liner 22 Piston ring 32 Pump 33 Water jet 34 Piston passage

Claims (12)

An internal combustion engine whose component parts slide against each other during operation,
a water supply device that supplies water to sliding surfaces between the component parts;
A control device that controls the operation of the internal combustion engine,
At least one of the sliding surfaces of the component parts is formed of silicon-based ceramics,
The control device controls the internal combustion engine so that low-load/no-load operation is performed in which the engine load is limited to a predetermined reference load or less until a predetermined standby period elapses after the internal combustion engine starts operating. and controlling the operation of the internal combustion engine so that normal operation is performed in which the engine load is not limited to below the reference load after the standby period has elapsed. The internal combustion engine according to claim 1, wherein the waiting period is a period required for the cumulative sliding distance between the sliding surfaces of the component parts to reach a predetermined constant distance. The internal combustion engine according to claim 2, wherein the waiting period is a predetermined constant time. further comprising a concentration parameter detection device that detects the value of a concentration parameter that changes depending on the concentration of impurities contained in the water supplied to the sliding surface,
The water supply device repeatedly supplies the water after being supplied to the sliding surface to the sliding surface,
The internal combustion engine according to claim 1, wherein the standby period is a period until a rate of change in the value of the concentration parameter detected by the concentration parameter detection device becomes equal to or less than a predetermined reference value. The internal combustion engine according to claim 4, wherein the concentration parameter is an electrical resistance of water supplied to the sliding surface. further comprising a resistance parameter detection device that detects a value of a resistance parameter that changes depending on the magnitude of sliding resistance between the component parts,
The waiting period is a period until the value of the resistance parameter detected by the resistance parameter detection device reaches a value indicating that the magnitude of the sliding resistance is equal to or less than a predetermined reference value. The internal combustion engine described in . the internal combustion engine is configured to be driven by a motor;
The internal combustion engine according to claim 6, wherein the resistance parameter is an output of the motor when the internal combustion engine is driven by the motor to a predetermined rotational speed. The internal combustion engine according to any one of claims 1 to 7, wherein the water supply device includes a filter that removes the silicon ceramic powder contained in the water supplied to the sliding surface. It further includes a storage section in which water is stored after being supplied to the sliding surface, and a stirring device that stirs the water stored in the storage section,
The water supply device supplies water stored in the storage section to the sliding surface,
The control device according to any one of claims 1 to 7 causes the stirring device to stir the water stored in the storage portion until the standby period has elapsed after the internal combustion engine starts operating. Internal combustion engine as described. The internal combustion engine according to any one of claims 1 to 7, comprising a cylinder and a piston ring provided on the outer periphery of a piston that reciprocates within the cylinder as the component parts that slide against each other. The water supply device includes a water jet that injects water toward the piston, and a piston passage provided in the piston,
The internal combustion engine according to claim 10, wherein the piston passage is formed such that water injected from the water jet flows into the piston passage and water in the piston passage is supplied to the piston ring. The internal combustion engine according to any one of claims 1 to 7, wherein the internal combustion engine is an internal combustion engine that uses hydrogen as fuel.

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