A cold start method for a methanol engine

Abstract

The present invention discloses a methanol engine cold starting method, wherein a heat source device is arranged between a methanol injection valve and an intake passage of a cylinder head, a central axis of the heat source device forms an angle with the central axis of the methanol injection valve, a hot spot of the heat source device is arranged at the apex of the angle, the heat source device is controlled by a program to enter a working state, the methanol injection valve sprays out liquid methanol when appropriate working conditions are met, the liquid methanol sprayed out from the nozzle of the methanol injection valve diffuses in a cone shape and completely passes through the hot spot of the heat source device to be vaporized into a gaseous state, and the methanol engine cold starting method can enable a single methanol fuel to be quickly vaporized during the engine cold starting process under cold air environment conditions to complete the cold starting work, and under the engine running condition, the cold intake air is heated into hot air by the engine's high-temperature water, and the hot air is then used to vaporize the liquid methanol, thereby ensuring that the engine can operate normally under cold air environment conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of engines, and in particular to a cold starting method for a methanol engine. Background Art

[0002] When the engine temperature reaches equilibrium with the ambient temperature after it stops and cools down, it is called the cold engine state. The action of restarting the engine is called a cold start.

[0003] Methanol is a liquid fuel that is not easy to vaporize or ignite. It is used to provide fuel for engine startup. Several commonly used cold start methods currently have the following defects: (1) The dual-fuel mixed ignition method fails to fully utilize methanol fuel, which is not conducive to reducing carbon emissions; (2) When the engine is cold started in a cold air environment, the ultrasonic atomization method of methanol requires frequent cleaning of the atomizer, which makes maintenance cumbersome; (3) The closed valve injection strategy that defines the start time of injection causes the vaporized methanol to escape into the exhaust pipe during the scavenging stroke, resulting in emission pollution and energy waste. At the same time, there is also the problem that the intake valve is at room temperature and cannot vaporize methanol during cold start; (4) The method of preheating the engine by heating the engine cooling water has a long heating time in a low temperature environment, which is not conducive to rapid engine startup. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the existing defects and provide a methanol engine cold start method, which can quickly vaporize a single methanol fuel during the engine cold start process under cold air environment conditions to complete the cold start work. Under the engine operating condition, a method is provided to heat the cold intake air into hot air through the engine's high-temperature water, and then use the hot air to vaporize liquid methanol, thereby ensuring that the engine can operate normally under cold air environment conditions, which can effectively solve the problems in the background technology.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solution: a methanol engine cold starting method, wherein a heat source device is provided between a methanol injection valve and an intake passage of a cylinder head, a central axis of the heat source device forms an angle with the central axis of the methanol injection valve, a hot spot of the heat source device is provided at the apex of the angle, the heat source device is controlled by a program to enter a working state, the methanol injection valve sprays liquid methanol when appropriate working conditions are met, the liquid methanol sprayed from the nozzle of the methanol injection valve diffuses in a conical shape and completely passes through the hot spot of the heat source device to be vaporized into a gaseous state, the gaseous methanol mixes with the hot air in the intake manifold to form a mixed gas which enters the engine cylinder, the mixed gas is ignited by a spark plug in the combustion chamber before the end of the compression stroke of the piston movement and burns rapidly, thereby completing the rapid cold starting of the methanol engine in a cold air environment, and the injection of liquid methanol into the intake manifold by the methanol injection valve must simultaneously meet the following conditions:

[0006] Condition 1: The hotspot temperature of the heat source device reaches the set temperature value;

[0007] Condition 2: The engine speed reaches the set speed value;

[0008] Condition 3: The exhaust valve on the engine's cylinder head is closed;

[0009] Condition 4: The intake valve on the engine's cylinder head is open.

[0010] As a preferred technical solution of the present invention, the methanol injection valve is installed on the intake manifold valve seat, and the intake manifold valve seat is arranged on the intake manifold of the composite intake pipe. The injection center axis of the methanol injection valve coincides with the center axis of the intake duct of the cylinder head.

[0011] As a preferred technical solution of the present invention, the nozzle of the methanol injection valve extends into the inner wall of the intake manifold by a distance of 2 mm.

[0012] As a preferred technical solution of the present invention, the heat source device is installed on the intake manifold and is located between the nozzle of the methanol injection valve and the intake duct of the cylinder head. The angle between the central axis of the heat source device and the central axis of the methanol injection valve is 30°.

[0013] As a preferred technical solution of the present invention, the heat source device uses direct current to operate, and the hot spot temperature of the heat source device is inversely proportional to the operating current.

[0014] As a preferred technical solution of the present invention, under the engine operating condition, the cold intake air is heated into hot air by the engine's high-temperature water, and the hot air is then used to gasify liquid methanol. The hot air in the intake manifold comes from the air cavity. The composite intake pipe includes an air cavity and a water cavity. The water cavity and the air cavity are isolated from each other. The air cavity is connected to the intake duct of the cylinder head through the intake manifold, and the water cavity is connected to the cylinder liner cooling water outside the cylinder liner.

[0015] Compared with the prior art, the beneficial effects of the present invention are: (1) the method of heating the cold intake air into hot air by the high-temperature water of the engine, and then using the hot air to vaporize the liquid methanol ensures that the engine can operate normally under cold air environment conditions. Compared with the method of using ultrasonic atomization of methanol in the prior art, the present invention adopts a heat source device to heat the methanol fuel, which can ensure that the liquid methanol fuel is heated into a vaporized state when passing through the hot spot, and is easy to implement, avoiding the cumbersome maintenance caused by cleaning the atomizer; (2) the engine speed reaches a suitable value of the rated starting speed value, and the reciprocating motion of the piston is used to inhale air that does not contain methanol fuel to purge the residual gas in the cylinder combustion chamber when the engine rotates. It can ensure that there is sufficient fresh air in the cylinder combustion chamber, which is conducive to the entry of the cylinder combustion chamber. The fuel is fully burned; (3) When liquid methanol is injected, the exhaust valve on the engine cylinder head is in a closed state. Compared with the closed valve injection strategy that defines the start time of injection in the prior art, the present invention can ensure that the fuel injected into the intake manifold fully enters the cylinder combustion chamber, avoiding the escape of methanol fuel into the exhaust pipe during the scavenging stroke, causing energy waste and emission pollution problems; (4) Compared with the method of heating air or methanol in the prior art, the present invention makes the liquid methanol fuel ejected from the nozzle of the methanol injection valve diffuse in a cone shape through the hot spot of the heat source device and is quickly vaporized into a gaseous state. The hot spot temperature is inversely proportional to the working current. When the hot spot temperature is low, the working current is large, which is conducive to rapid heating. When the hot spot temperature is high, the working current is small, which is conducive to constant temperature. This solves the problem that the intake valve is at room temperature and cannot vaporize methanol during the first startup. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the working structure of the present invention.

[0017] In the figure: 100 liquid methanol, 101 intake manifold valve seat, 102 methanol injection valve, 103 conical injection shape, 104 heat source device, 105 cylinder head, 106 intake duct, 107 intake valve, 108 combustion chamber, 109 cylinder liner, 110 cylinder liner cooling water, 111 water cavity, 112 air cavity, 113 composite intake pipe. DETAILED DESCRIPTION

[0018] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments (for the convenience of description and understanding, the following is Figure 1 Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present invention.

[0019] Example 1: Please refer to Figure 1The present invention provides a technical solution: a methanol engine cold start method, wherein a methanol injection valve 102 is provided on the intake manifold of a composite intake pipe 113, the methanol injection valve 102 is mounted on the composite intake pipe 113 via an intake manifold valve seat 101, the injection center axis of the methanol injection valve 102 coincides with the center axis of the intake passage 106 of the cylinder head 105, a heat source device 104 operated by direct current is provided between the methanol injection valve 102 and the intake passage 106 of the cylinder head 105, the center axis of the heat source device 104 being at an angle to the center axis of the methanol injection valve 102, and the hot spot of the heat source device 104 being at an angle to the hot spot of the heat source device 104. Set at the vertex of the angle, the heat source device 104 is controlled by the program to enter the working state when the engine start button is pressed. The methanol injection valve 102 sprays liquid methanol 100 when the working conditions 1-4 are met at the same time. The liquid methanol 100 sprayed from the nozzle of the methanol injection valve 102 spreads in a cone shape and all passes through the hot spot of the heat source device 104 and is vaporized into a gas. The gaseous methanol mixes with the hot air in the intake manifold to form a mixed gas that enters the engine cylinder. The mixed gas is ignited by the spark plug in the combustion chamber 108 before the end of the compression stroke of the piston movement and burns rapidly, completing the rapid cold start of the methanol engine in a cold air environment.

[0020] This embodiment describes the specific method in conjunction with a single-cylinder engine as follows:

[0021] The composite intake pipe 113 is provided with an air cavity 112 and a water cavity 111. When the engine is running, the cylinder liner cooling water 110 outside the cylinder liner 109 on the engine can enter the water cavity 111. The heat generated by the combustion process in the cylinder combustion chamber 108 turns the cylinder liner cooling water 110 outside the cylinder liner 109 into hot water and enters the water cavity 111. The heat is transferred to the air cavity 112 through the water cavity 111. The hot water generated during the operation of the engine is used to heat the air in the air cavity 112 of the composite intake pipe into hot air. The liquid methanol 100 fuel ejected from the nozzle of the methanol injection valve 102 is diffused into the hot air in the intake manifold in the shape of a cone jet 103. The hot air is used to vaporize the liquid methanol 100 to form a mixed gas that enters the engine cylinder. The mixed gas is ignited and burned quickly by the spark plug in the combustion chamber 108 before the end of the compression stroke of the piston movement, ensuring the normal operation of the engine under cold air environment conditions.

[0022] Among them, the nozzle of the methanol injection valve 102 extends into the inner wall of the intake manifold by 2 mm, ensuring that the liquid methanol 100 sprayed by the methanol injection valve 102 cannot splash onto the inner wall of the intake manifold and the inner wall of the intake duct 106 of the cylinder head 105. It is easy to understand that when this method is applied to a multi-cylinder engine, it has the same effect.

[0023] The heat source device 104 is installed on the intake manifold and is located between the nozzle of the methanol injection valve 102 and the intake duct 106 of the cylinder head 105. The angle between the central axis of the heat source device 104 and the central axis of the methanol injection valve 102 is 30°, ensuring that the liquid methanol 100 fuel is sprayed out and diffuses in a cone shape 103 and is completely vaporized into a gaseous state through the hot spot of the heat source device 104. It is easy to understand that when this method is applied to a multi-cylinder engine, it has the same effect.

[0024] In this embodiment, the heat source device 104 operates with a 24V DC power supply. The hotspot temperature of the heat source device 104 is inversely proportional to the operating current. When the hotspot temperature increases, the operating current of the heat source device decreases. When the hotspot temperature decreases, the operating current of the heat source device increases. When the hotspot temperature remains unchanged, the current of the heat source device remains unchanged.

[0025] The working parameter conditions are: when the ambient air temperature is 5°C, the working current value of the heat source device is 10A; when the hot spot temperature reference value is 65°C, the working current value of the heat source device is 1.7A; when the hot spot temperature reference value is 70°C, the working current value of the heat source device is 1.0A. The control program obtains the hot spot temperature value by monitoring the working current of the heat source device 104.

[0026] The methanol injection valve 102 injects liquid methanol into the intake manifold only if the following conditions are met simultaneously:

[0027] Condition 1: The hotspot temperature of heat source device 104 reaches a set temperature value of 70°C. At this time, the operating current value of the heat source device is 1.0A. The purpose is to ensure that liquid methanol 100 fuel ejected from the nozzle of methanol injection valve 102 diffuses in a conical shape 103 through the 70°C hotspot of heat source device 104 and is quickly vaporized into a gaseous state. Compared with the prior art method of heating air or methanol, the present invention is not affected by changes in ambient temperature and is conducive to widespread use. Compared with the prior art method of vaporizing methanol using the temperature of the intake valve, the present invention solves the problem of the inability to vaporize methanol at the initial startup when the intake valve is at room temperature by controlling the hotspot temperature at 70°C.

[0028] Condition 2: The engine speed reaches 60% of the set rated starting speed of 150 r / min. At this time, the engine speed is 90 r / min. The purpose is to use the reciprocating motion of the piston to draw in air that does not contain methanol fuel 100 to purge the residual gas in the combustion chamber 108, thereby ensuring sufficient fresh air in the combustion chamber 108 and facilitating the complete combustion of the fuel in the combustion chamber 108.

[0029] Condition 3: The exhaust valve on the engine's cylinder head 105 is closed. Compared to the prior art closed-valve injection strategy that defines the start of fuel injection, the present invention ensures that the fuel injected into the intake manifold fully enters the combustion chamber 108, preventing methanol fuel from escaping into the exhaust pipe during the scavenging stroke, which would cause energy waste and emission pollution.

[0030] Condition 4: The intake valve 107 on the engine's cylinder head 105 is in an open state, the purpose of which is to ensure that the liquid methanol fuel 100 passes through the hot spot of the heat source device 104 and is quickly vaporized into a gaseous state, and completely enters the engine cylinder combustion chamber 108 along with the air before the intake valve 107 is closed; it can be understood that the methanol fuel 100 cannot be injected when the intake valve 107 is in a closed state, thereby avoiding fuel waste caused by the inability of the gaseous methanol fuel to enter the combustion chamber 108 of the engine cylinder.

[0031] Further, the cold start process and method of the present invention are described in conjunction with this embodiment: When the engine is in a cold state, the temperature of the engine and the ambient air temperature are balanced. At this time, the ambient air temperature is 5°C, the initial temperature of the engine cylinder water is 5°C, and the liquid methanol temperature is also 5°C. It is easy to understand that the embodiment Figure 1 The temperature of the included device is also 5°C. When preparing to start the engine, the hot spot temperature of the heat source device 104 is 5°C. The 24V DC starts to use a working current of 10A to quickly heat the hot spot temperature from 5°C. The control program obtains the hot spot temperature by monitoring the working current of the heat source device 104. When the working current value of the heat source device is 1.7A, the hot spot temperature reference value is 65°C. When the working current value of the heat source device is 1.0A, the hot spot temperature reference value is 70°C. The control program is set with a temperature reference value of 65°C and a temperature reference value of 70°C. When the hotspot temperature is lower than the 65°C temperature reference, the engine start button is pressed, and the starter motor does not work. The heat source device 104 continues to heat up to prevent cold air from entering when the engine is rotating, which is conducive to a rapid increase in the hotspot temperature of the heat source device 104. When the hotspot temperature reaches the 65°C temperature reference, the control program starts the starter motor to drive the engine to rotate. When the above conditions 1-4 cannot be met at the same time, the methanol injection valve 102 does not inject liquid methanol 100 fuel into the intake manifold. For ease of understanding, the indicative example can be understood as follows:

[0032] Example 1: When the hot spot temperature does not reach the 70°C temperature reference set in condition 1, and the engine speed does not reach the 90 r / min set in condition 2, the methanol injection valve 102 does not inject liquid methanol 100 fuel into the intake manifold to prevent the liquid methanol 100 from failing to vaporize and causing ignition failure.

[0033] Example 2: When the hot spot temperature reaches the 70°C temperature reference set in condition 1 and the engine speed does not reach the 90r / min set in condition 2, the methanol injection valve 102 does not inject liquid methanol 100 fuel into the intake manifold, allowing the cylinder to be fully ventilated and enter fresh air.

[0034] Example 3: When the hot spot temperature reaches the 70°C temperature reference set in condition 1, and the engine speed reaches the engine speed of 90 r / min set in condition 2, and the exhaust valve is not in a closed state and condition 3 is not satisfied, and the intake valve 107 is in an open state and condition 4 is satisfied, the methanol injection valve 102 does not spray liquid methanol 100 fuel into the intake manifold, so as to prevent vaporized methanol from being blown into the exhaust pipe, causing fuel waste and pollution.

[0035] The engine starter motor starts working to drag the engine to rotate. When the heat source device 104 uses 24V DC to make the hot spot temperature reach the 70℃ temperature reference set in condition 1, and the engine speed reaches the engine speed set in condition 2, 90r / min, and the exhaust valve is in a closed state to meet condition 3, and the intake valve 107 is in an open state to meet condition 4, the liquid methanol 100 fuel sprayed from the nozzle of the methanol injection valve 102 is in a cone shape 103 and diffuses through the hot spot temperature of 70℃ of the heat source device 104 and is vaporized into a gas. The gaseous methanol mixes with the air in the intake manifold to form a mixture that enters the engine cylinder. The mixture is ignited by the spark plug in the combustion chamber 108 before the end of the compression stroke of the piston movement and burns rapidly, completing the cold start of the methanol engine and ensuring that the engine enters the idle speed of 600r / min.

[0036] During engine operation, a method is provided for heating cold intake air into hot air through high-temperature water in the engine, and then using the hot air to vaporize liquid methanol 100. When conditions 3 and 4 are met at the same time, the liquid methanol 100 fuel ejected from the nozzle of the methanol injection valve 102 is diffused in a conical shape 103 and vaporized by the hot air in the intake manifold to form a mixture that enters the engine cylinder combustion chamber 108. The mixture is ignited by the spark plug in the combustion chamber 108 before the end of the compression stroke of the piston movement and burns rapidly, ensuring that the engine can operate normally under cold air environment conditions.

[0037] In a low temperature environment, the initial temperature of the cylinder liner cooling water 110 is 5°C. After the engine is successfully started and runs at an idle speed of 600r / min, the temperature of the cylinder liner cooling water 110 gradually increases from 5°C and becomes hot water and enters the water chamber 111. The heat of the hot water in the water chamber 111 is transferred to the air chamber 112 to gradually heat up the 5°C cold air. When the heated air temperature is lower than 65°C, for example, the air temperature is heated to 45°C, the hot spot temperature of the heat source device 104 is inversely proportional to the working current. The lower the temperature of the heat source device 104, the greater the working current. The hotspot temperature is maintained at 70°C. When conditions 3 and 4 are met at the same time, the liquid methanol 100 fuel ejected from the nozzle of the methanol injection valve 102 continues to vaporize into a gaseous state using the hotspot temperature. The gaseous methanol mixes with the air in the intake manifold to form a mixed gas that enters the engine cylinder. The mixed gas is ignited by the spark plug in the combustion chamber 108 before the end of the compression stroke of the piston movement and burns rapidly, thereby solving the problem of insufficient heating of the cold air due to the low water temperature in the water chamber when the engine is running at low power, and ensuring that the methanol engine can operate at an idle speed of 600r / min after a successful cold start.

[0038] Furthermore, when the temperature of the cylinder jacket water gradually rises to above 65°C, the heat of the hot water in the water chamber 111 is transferred to the air chamber 112 to heat the 5°C cold air into hot air, but fails to reach 65°C. The heat source device 104 maintains the hot spot temperature at 65°C with an operating current of 1.7A. When conditions 3 and 4 are met, the liquid methanol 100 fuel sprayed from the nozzle of the methanol injection valve 102 is simultaneously vaporized into a gaseous state by the hot air and the hot spot temperature in the intake manifold to form a mixed gas that enters the engine cylinder. The mixed gas is ignited and burned rapidly in the combustion chamber 108 by the spark plug before the end of the compression stroke of the piston movement, thereby achieving the purpose of using self-produced hot water to heat the cold air in the air chamber 112 during the operation of the engine, thereby ensuring that the engine can operate in a low-temperature environment. Compared with the prior art, the present invention can avoid the cold and hot shock to the engine caused by the excessive temperature difference between the intake temperature and the normal operating temperature of the engine in a low-temperature environment, thereby improving the service life of the engine.

[0039] Furthermore, after the jacket water temperature gradually rises to 80°C, the jacket water temperature for normal engine operation, the heat of the hot water in the water chamber 111 is transferred to the air chamber 112 to heat the 5°C cold air into 65°C hot air. It is easy to understand that the hot spot temperature of the heat source device 104 is heated to 65°C by the hot air. By utilizing the inverse proportional relationship between the hot spot temperature of the heat source device 104 and the working current, the working current of the heat source device 104 is reduced to a state where the hot spot is not heated. When conditions 3 and 4 are met, the liquid methanol 100 fuel ejected from the nozzle of the methanol injection valve 102 diffuses in a cone shape 103 and is vaporized in the 65°C hot air in the intake manifold to form a mixture that enters the combustion chamber 108. The mixture is ignited by the spark plug in the combustion chamber 108 before the end of the compression stroke of the piston movement and burns rapidly, completing the normal operation of the methanol engine.

[0040] Under program control, the heat source device 104 starts working when the engine is about to be started, keeps working during the normal operation of the engine, and stops working when the engine is stopped.

[0041] When the engine is running at high power, the water temperature in the water chamber 111 is high and the air is heated sufficiently. At this time, the hot spot temperature of the heat source device 104 is high, the resistance is large, the current is small, and the heat generated is small. The liquid methanol 100 fuel ejected from the nozzle of the methanol injection valve 102 is vaporized by the hot air in the intake manifold.

[0042] When the engine is running at high power, the water temperature in the water chamber 111 is high and the air is heated sufficiently. At this time, the hot spot temperature of the heat source device 104 is high and the current is small, and the heat generated is small. The liquid methanol 100 fuel ejected from the nozzle of the methanol injection valve 102 is vaporized by the hot air in the intake manifold.

[0043] In the high-temperature environment embodiment, hot water can be controlled not to enter the water chamber 111, ensuring that the air cannot be heated when the engine is working in a high-temperature environment.

[0044] Example 2: The difference from Example 1 is that the heat source device in this cold start method can also use alternating current.

[0045] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A methanol engine cold start method, characterized by: A heat source device (104) is provided between the methanol injection valve (102) and the intake passage (106) of the cylinder head (105). The central axis of the heat source device (104) and the central axis of the methanol injection valve (102) form an angle. The hot spot of the heat source device (104) is provided at the vertex of the angle. The heat source device (104) enters a working state under program control. When the methanol injection valve (102) meets appropriate working conditions, liquid methanol (100) is sprayed out. The liquid methanol (100) ejected from the outlet diffuses in a conical shape and passes through the hot spot of the heat source device (104) to be vaporized into a gaseous state. The gaseous methanol is mixed with the hot air in the intake manifold to form a mixed gas that enters the engine cylinder. The mixed gas is ignited by the spark plug in the combustion chamber (108) before the end of the compression stroke of the piston movement and burns quickly, completing the rapid cold start of the methanol engine in a cold air environment. The methanol injection valve (102) must meet the following conditions when injecting liquid methanol into the intake manifold: Condition 1: The hot spot temperature of the heat source device (104) reaches the set temperature value; Condition 2: The engine speed reaches the set speed value; Condition 3: The exhaust valve on the cylinder head (105) of the engine is in a closed state; Condition 4: The intake valve (107) on the cylinder head (105) of the engine is in the open state.

2. A methanol engine cold start method according to claim 1, characterized in that: The methanol injection valve (102) is mounted on an intake manifold valve seat (101), which is arranged on an intake manifold of a composite intake pipe (113), and an injection center axis of the methanol injection valve (102) coincides with a center axis of an intake passage (106) of a cylinder head (105).

3. The methanol engine cold start method according to claim 1, characterized in that: The nozzle of the methanol injection valve (102) extends into the inner wall of the intake manifold by a distance of 2 mm.

4. The methanol engine cold start method according to claim 1, characterized in that: The heat source device (104) is installed on the intake manifold and is located between the nozzle of the methanol injection valve (102) and the intake passage (106) of the cylinder head (105). The angle between the central axis of the heat source device (104) and the central axis of the methanol injection valve (102) is 30 degrees.

5. The methanol engine cold start method according to claim 1, characterized in that: The heat source device (104) operates with direct current, and the hot spot temperature of the heat source device (104) is inversely proportional to the operating current.

6. A methanol engine cold start method according to claim 2, characterized in that: In the engine operating condition, the cold intake air is heated into hot air by high-temperature water in the engine, and the hot air is then used to gasify liquid methanol. The hot air in the intake manifold comes from the air cavity (112). The composite intake pipe (113) includes the air cavity (112) and the water cavity (111). The water cavity (111) and the air cavity (112) are isolated from each other. The air cavity (112) is connected to the intake passage (106) of the cylinder head (105) through the intake manifold, and the water cavity (111) is connected to the cylinder liner cooling water (110) outside the cylinder liner (109).

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