hydrogen engine

Abstract

To suppress generation of emulsion in a one-way valve provided in a ventilation system of a crankcase.SOLUTION: A ventilation system for an engine includes: an air introduction passage communicating an intake passage and a crankcase; a one-way valve 60 for limiting a gas flow from the crankcase toward the intake passage through the air introduction passage; and a valve housing 50 fixed to an oil pan 14 constituting an outer wall of the crankcase. The one-way valve 60 is mounted to the crankcase while sandwiched between the oil pan 14 and the valve housing 50.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an engine with a crankcase ventilation system. [Background technology]

[0002] As shown in Patent Document 1, there is known an engine equipped with a ventilation system that ventilates blow-by gases in the crankcase by introducing air from the intake passage into the crankcase. The ventilation system of this engine is provided with a one-way valve to prevent gas from flowing back from the crankcase to the intake passage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-185181 Summary of the Invention [Problem to be solved by the invention]

[0004] The one-way valve in the ventilation system described above is exposed to blow-by gas, which contains moisture and oil. If the temperature of the one-way valve or its surroundings is low, the moisture in the blow-by gas condenses. The condensed water may then be mixed with oil, causing an emulsion. [Means for solving the problem]

[0005] An engine that solves the above problem is an engine equipped with a ventilation system that introduces air from an intake passage into a crankcase to ventilate the crankcase, the ventilation system comprising an air inlet passage that connects the intake passage with the crankcase, a one-way valve that restricts the flow of gas from the crankcase to the intake passage through the air inlet passage, and a valve housing fixed to the outer wall of the crankcase, the one-way valve being attached to the crankcase while being sandwiched between the crankcase and the valve housing. [Effects of the Invention]

[0006] The engine has the effect of suppressing the generation of emulsion. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating a schematic configuration of an embodiment of an engine. FIG. [Figure 2] FIG. 2 is a side view of the oil pan and its vicinity of the engine. [Figure 3] 3 is a cross-sectional view showing the cross-sectional structure of the valve housing of the engine and its vicinity taken along line 3-3 in FIG. 2. [Figure 4] 4 is a cross-sectional view showing the cross-sectional structure of the valve housing of the engine and its vicinity taken along line 4-4 in FIG. 2. [Figure 5] FIG. 10 is a cross-sectional view of a one-way valve and its vicinity in another embodiment of the engine. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the engine will be described in detail below with reference to FIGS. <About the configuration of Engine 10> First, the configuration of an engine 10 will be described with reference to Figure 1. The engine 10 shown in Figure 1 is a hydrogen engine that generates power by burning hydrogen. In the case of a hydrogen engine, combustible hydrogen may be contained in blow-by gas. For this reason, hydrogen engines are required to have higher blow-by gas ventilation performance than gasoline or diesel engines.

[0009] The engine 10 includes a cylinder block 11. A plurality of cylinders 12 are formed inside the cylinder block 11. FIG. 1 shows only one of the cylinders 12. A piston 13 is housed in each cylinder 12 so that it can reciprocate freely. A combustion chamber 17 for burning hydrogen is formed above the piston 13 in each cylinder 12. An oil pan 14 for storing oil is attached to the bottom of the cylinder block 11. A crankcase 15 is formed below the cylinders 12 inside the cylinder block 11. A cylinder head 16 is attached to the top of the cylinder block 11. Individual intake ports 18 and exhaust ports 19 are formed inside the cylinder head 16 for each cylinder 12. A head cover 16A is attached to the top of the cylinder head 16. A valve train chamber 20 for accommodating a valve train is formed inside the upper part of the cylinder head 16 covered by the head cover 16A.

[0010] The engine 10 is equipped with an intake passage 21, which is a passage through which air is introduced into the combustion chamber 17, and an exhaust passage 22, which is a passage through which exhaust gas is discharged from the combustion chamber 17. An air cleaner 23 is provided in the intake passage 21 to filter dust and the like in the air. A compressor 24 is provided in the intake passage 21 downstream of the air cleaner 23. The compressor 24, together with a turbine 25 provided in the exhaust passage 22, constitutes a turbocharger. An intercooler 26 is provided in the intake passage 21 downstream of the compressor 24. The intercooler 26 is a heat exchanger for cooling air that has been heated by compression in the compressor 24. A throttle valve 27 is provided in the intake passage 21 downstream of the intercooler 26. The throttle valve 27 is a valve for adjusting the flow rate of air sent to the combustion chamber 17 through the intake passage 21. The intake passage 21 branches off for each cylinder 12 at an intake manifold 28 provided downstream of a throttle valve 27. The intake manifold 28 is connected to the combustion chamber 17 through an intake port 18.

[0011] The engine 10 is equipped with an injector 29 that injects hydrogen into the air used for combustion in the combustion chamber 17. In the case of Figure 1, the injector 29 is installed so as to inject hydrogen into the intake port 18, but the injector 29 may also be installed so as to inject hydrogen into the combustion chamber 17. The engine 10 further includes an intake valve 32 that opens and closes the intake port 18 to the combustion chamber 17, and an exhaust valve 33 that opens and closes the exhaust port 19 to the combustion chamber 17.

[0012] <About the ventilation system> The engine 10 is equipped with a ventilation system for the crankcase 15. The ventilation system has three passages, a first passage R1, a second passage R2, and a third passage R3, which connect the intake passage 21 and the crankcase 15.

[0013] The first passage R1 is a passage that connects the crankcase 15 to a portion of the intake passage 21 downstream of the throttle valve 27. The first passage R1 is composed of a blow-by gas passage 40, a first separator 41, a PCV valve 42, a first PCV hose 43, and a second separator 44. The first separator 41 and the second separator 44 are separators that separate oil mist from the blow-by gas flowing through the first passage R1. The first separator 41 is attached to the inside of the head cover 16A. The blow-by gas passage 40 is a passage that passes through the inside of the cylinder block 11 and the cylinder head 16 and connects the crankcase 15 to the first separator 41. The second separator 44 is provided in a portion of the blow-by gas passage 40 in the cylinder block 11. The first PCV hose 43 is a hose that connects the first separator 41 to the intake manifold 28. The PCV valve 42 is a valve that allows gas to flow from the inside of the crankcase 15 to the intake passage 21 through the first passage R1, while restricting gas from flowing from the intake passage 21 to the inside of the crankcase 15 through the first passage R1. The PCV valve 42 is installed at a connection portion of the first PCV hose 43 to the first separator 41.

[0014] The second passage R2 is a passage that connects the crankcase 15 to a portion of the intake passage 21 downstream of the compressor 24. In the case of FIG. 1, the second passage R2 is configured to connect the intake manifold 28 to the crankcase 15. The second passage R2 is configured by a second PCV hose 45 and a one-way valve 60. The second PCV hose 45 is a hose that connects the crankcase 15 to the intake manifold 28. The one-way valve 60 is a valve that allows air to flow from the intake passage 21 to the crankcase 15 through the second passage R2, while restricting gas flow from the crankcase 15 to the intake passage 21 through the second passage R2. In the case of the engine 10 of this embodiment, the one-way valve 60 is attached to the crankcase 15. The attachment structure of the one-way valve 60 to the crankcase 15 will be described in detail later.

[0015] The third passage R3 is a passage that connects the crankcase 15 to a portion of the intake passage 21 upstream of the compressor 24. The third passage R3 is composed of an oil return passage 47, a valve train chamber 20, a third separator 48, and a third PCV hose 49. The oil return passage 47 passes through the interior of the cylinder block 11 and the cylinder head 16 and connects the valve train chamber 20 to the crankcase 15. The oil return passage 47 functions as a passage for returning oil from the valve train chamber 20 to the oil pan 14, and also as a passage for distributing gas between the valve train chamber 20 and the crankcase 15. The third separator 48 is a separator that separates oil mist from the blow-by gas flowing through the third passage R3. The third separator 48 is installed inside the head cover 16A. The third PCV hose 49 is a hose that connects a portion of the intake passage 21 downstream of the air cleaner 23 and upstream of the compressor 24 to the third separator 48.

[0016] When the engine 10 is operating in a naturally aspirated state, the portion of the intake passage 21 downstream of the throttle valve 27 becomes negative pressure. This negative pressure causes blow-by gas in the crankcase 15 to be drawn into the intake passage 21 through the first passage R1. Air is also introduced into the crankcase 15 through the third passage R3. On the other hand, when the engine 10 is operating in a supercharged state, the portion of the intake passage 21 downstream of the compressor 24 becomes positive pressure. At this time, the positively pressurized air is introduced from the intake passage 21 into the crankcase 15 through the second passage R2. The introduced air then pushes out the blow-by gas in the crankcase 15 and releases it into the intake passage 21 through the third passage R3.

[0017] <Installation structure of one-way valve 60> In the engine 10 of this embodiment, the one-way valve 60 that restricts the flow direction of gas in the second passage R2 is attached directly to the crankcase 15. Hereinafter, the attachment structure of the one-way valve 60 to the crankcase 15 will be described with reference to FIGS. 2 to 4. FIG. 2 shows a side view of the oil pan 14 of the engine 10 and its vicinity. FIG. 3 shows a cross-sectional structure of the valve housing 50 and its vicinity taken along line 3-3 in FIG. 2. FIG. 4 shows a cross-sectional structure of the valve housing 50 and its vicinity taken along line 4-4 in FIG. 2. The engine 10 is provided with a valve housing 50 for attaching the one-way valve 60 to the crankcase 15.

[0018] As shown in Fig. 2, the valve housing 50 is fixed to the outer side wall of the oil pan 14 by bolts 51. In the case of Fig. 2, the valve housing 50 is fixed by two bolts 51. The valve housing 50 may be fixed by one bolt 51, or by three or more bolts 51.

[0019] 3 and 4, the one-way valve 60 has a generally cylindrical shape with a through-hole 61 that extends from one end to the other. One end of the through-hole 61 serves as an inlet 62 for air from the intake passage 21. The other end of the through-hole 61 serves as an outlet 63 for air into the crankcase 15. The one-way valve 60 also has a flange 64 that has a larger outer diameter than other portions. In the following description, the portion of the one-way valve 60 that is closer to the inlet 62 than the flange 64 will be referred to as a front end 65. The portion of the one-way valve 60 that is closer to the outlet 63 than the flange 64 will be referred to as a rear end 66.

[0020] 3 and 4, the one-way valve 60 has a built-in check mechanism. The check mechanism is a mechanism for restricting the flow of gas from the discharge port 63 through the through hole 61 toward the inlet 62. The check mechanism may be a well-known mechanism made up of, for example, a valve body and a spring for biasing the valve body.

[0021] A boss 70 is provided at a portion of the crankcase 15 where the one-way valve 60 is attached. The boss 70 has an insertion hole 71 that communicates between the inside and outside of the crankcase 15. The portion of the insertion hole 71 that faces inside the crankcase 15 is a small-diameter portion 72 into which the front end portion 65 of the one-way valve 60 is inserted. The portion of the insertion hole 71 that faces outside the crankcase 15 is a large-diameter portion 73 that accommodates the flange portion 64 of the one-way valve 60. A step portion 74 having a surface perpendicular to the extension direction of the insertion hole 71 is provided between the small-diameter portion 72 and the large-diameter portion 73 of the insertion hole 71. Note that a bolt hole is formed in a portion of the boss 70 that is not shown in the cross-sectional views of FIGS. 3 and 4 , into which a bolt 51 for fixing the valve housing 50 is fastened.

[0022] The valve housing 50 is formed with an insertion hole 52 into which a rear end portion 66 of the one-way valve 60 is inserted. The valve housing 50 also has a communication hole 53 that extends from its outer periphery to the insertion hole 52. The second PCV hose 45 is connected to the communication hole 53 via a joint 54. The one-way valve 60 is attached to the crankcase 15 with the flange portion 64 sandwiched between the valve housing 50 and a step portion 74 provided in an insertion hole 71 of the crankcase 15.

[0023] In the following description, a state in which a vehicle equipped with engine 10 is stationary on a horizontal plane will be referred to as a reference state. "SO" in Fig. 4 indicates a reference oil level, which is the engine oil level in crankcase 15 when an amount of engine oil at the upper limit of the appropriate range is poured into engine 10 in the reference state. One-way valve 60 is attached to crankcase 15 so that, in the reference state, discharge port 63 is positioned vertically above the reference oil level. Furthermore, one-way valve 60 is attached to crankcase 15 so that, in the reference state, the discharge direction of air from discharge port 63 is horizontal.

[0024] <Operation of the embodiment> The engine 10 of this embodiment is configured as a hydrogen engine that generates power by burning hydrogen. The engine 10 is equipped with a one-way valve 60 at a location of the crankcase 15 that is exposed to blow-by gas.

[0025] Blow-by gas contains oil and water. When the temperature of the one-way valve 60 or its surroundings is low, the water in the blow-by gas condenses and liquefies. The condensed water may then mix with the oil, forming an emulsion. In addition, in a low-temperature environment, if the engine 10 is stopped with condensed water remaining inside the one-way valve 60, the remaining water may freeze while the engine 10 is stopped. The next time the engine 10 is operated, the one-way valve 60 may not operate properly until the ice melts.

[0026] In contrast, the one-way valve 60 of the engine 10 of this embodiment is attached directly to the crankcase 15. The one-way valve 60 is surrounded by the valve housing 50. The one-way valve 60 attached in this manner is quickly warmed up by the heat received from the crankcase 15 after the engine 10 is started, even if the temperature is low before the engine 10 is started. This prevents emulsion and freezing from occurring in the one-way valve 60.

[0027] <Effects of the embodiment> According to the engine 10 of the present embodiment described above, the following effects can be achieved. (1) The engine 10 includes a second passage R2, which is an air introduction passage that connects the intake passage 21 and the crankcase 15, and a one-way valve 60 that restricts the flow of gas from the crankcase 15 to the intake passage 21 through the second passage R2. The engine 10 is configured to ventilate the crankcase 15 by introducing air from the intake passage 21 to the crankcase 15 through the second passage R2. The engine 10 also includes a valve housing 50 that is fixed to an outer wall of the crankcase 15. The one-way valve 60 is directly attached to the crankcase 15 and sandwiched between the crankcase 15 and the valve housing 50. The one-way valve 60 that is directly attached to the crankcase 15 is warmed by heat received from the crankcase 15. This prevents emulsion and freezing in the one-way valve 60 due to low temperatures.

[0028] (2) If the air discharged from the one-way valve 60 is blown directly onto the engine oil, the oil surface will become rippled. As a result, the air bubble content of the engine oil may increase. Furthermore, the blowing of air increases the amount of engine oil that becomes mist. The mist is returned to the intake air along with blow-by gas in the crankcase 15 and burned in the combustion chamber 17, which also increases engine oil consumption. In contrast, in the engine 10 of this embodiment, the one-way valve 60 is installed so that the direction of air discharge from the outlet 63 of the one-way valve 60 into the crankcase 15 is horizontal when the vehicle equipped with the engine 10 is stationary on a horizontal plane. Furthermore, the one-way valve 60 is attached to the crankcase 15 so that the outlet 63 is positioned vertically above the reference oil level in the reference state. Therefore, the air discharged from the outlet 63 of the one-way valve 60 is less likely to be blown directly onto the engine oil stored in the crankcase 15. Therefore, an increase in the foam content of the engine oil and an increase in the amount of engine oil consumed due to carry-away are suppressed.

[0029] (3) The engine 10 of this embodiment is configured as a hydrogen engine that generates power by burning hydrogen. Because water is produced when hydrogen is burned, hydrogen engines tend to have a higher amount of moisture in the blow-by gas than gasoline engines, diesel engines, etc. The greater the amount of moisture in the blow-by gas, the greater the amount of condensed water that forms in the one-way valve 60 at low temperatures. For this reason, the mounting structure for the one-way valve 60, which can warm the one-way valve 60 by receiving heat from the crankcase 15, is particularly suitable for use in hydrogen engines.

[0030] (Other embodiments) This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0031] 5 is configured so that the one-way valve 60 is attached to the crankcase 15 by sandwiching the flange portion 64 between the valve housing 500 and the crankcase 15 with a portion of the rear end portion 66 protruding outward. The second PCV hose 45 is connected to the portion of the rear end portion 66 of the one-way valve 60 protruding from the valve housing 500. As described above, the shape of the valve housing 50 can be changed as appropriate as long as it has the function of sandwiching and fixing the one-way valve 60 between itself and the outer wall of the crankcase 15.

[0032] In the above embodiment, the one-way valve 60 is attached to the crankcase 15 in a position such that the direction in which air is discharged from the discharge port 63 is horizontal in the standard state. However, the one-way valve 60 may be attached to the crankcase 15 in a position different from this.

[0033] The configuration of the ventilation system for the engine 10 can be modified as appropriate as long as it includes the second passage R2 provided with the one-way valve 60. For example, if ventilation of the crankcase 15 is not required during naturally aspirated operation, the first passage R1 may be omitted.

[0034] The engine 10 may be an engine other than a hydrogen engine. (Additional notes) [Appendix 1] An engine that introduces air from an intake passage into a crankcase to ventilate the crankcase, the engine comprising: an air inlet passage that connects the intake passage with the crankcase; a one-way valve that restricts the flow of gas from the crankcase to the intake passage through the air inlet passage; and a valve housing fixed to an outer wall of the crankcase, the one-way valve being attached to the crankcase while being sandwiched between the crankcase and the valve housing.

[0035] [Appendix 2] The engine described in Appendix 1, wherein the engine is mounted on a vehicle, and the one-way valve is installed so that the direction of air discharge from the one-way valve into the inside of the crankcase is horizontal when the vehicle is stationary on a horizontal surface.

[0036] [Appendix 3] The engine according to appendix 1 or 2, which is a hydrogen engine that generates power by burning hydrogen. [Explanation of symbols]

[0037] 10 Engine 11 Cylinder block 12 cylinders 13 Piston 14 Oil pan 15 Crankcase 16 Cylinder head 16A Headcover 17 Combustion chamber 18 Intake port 19 Exhaust port 20 Valve train chamber 21 Intake passage 22 Exhaust passage 23 Air cleaner 24 Compressor 25 Turbine 26 Intercooler 27 Throttle valve 28 intake manifold 29 Injector 32 Intake valve 33 Exhaust valve 40 Blow-by gas passage 41 First separator 42 PCV valve 43 First PCV hose 44 Block side separator 45 Second PCV hose 46 Passage 48 Third separator 49 3rd PCV hose 50,500 Valve Housing 51 volts 52 Insertion hole 53 Communication hole 54 Joint 60 One-way valve 61 Through hole 62 Inlet 63 Discharge port 64 Flange 65 Front end 66 Rear end 70 Boss 71 Insertion hole 72 Small diameter section 73 Large diameter section 74 Step part

Claims

1. A hydrogen engine that introduces air from an intake passage into a crankcase to ventilate the crankcase and burns hydrogen to generate power, an air introduction passage that communicates the intake passage with the crankcase; a one-way valve that restricts the flow of gas from the crankcase toward the intake passage through the air introduction passage; a valve housing fixed to an outer wall of the crankcase; and the one-way valve is attached to the crankcase in a state sandwiched between the crankcase and the valve housing. Hydrogen engine.

2. The hydrogen engine is installed in a vehicle, The one-way valve is installed so that the direction of air discharge from the one-way valve into the crankcase is horizontal when the vehicle is stationary on a horizontal surface.

2. The hydrogen engine according to claim 1.

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