Blow-by gas treatment device

Abstract

To provide a blow-by gas treatment device capable of coping with laws and regulations on coming-off of a PCV valve, and preventing (or suppressing) a turbid liquid in which oil contained in blow-by gas and condensed water generated by condensation of moisture contained in the blow-by gas are mixed from flowing into the PCV valve.SOLUTION: The blow-by gas treatment device 60 includes a PCV valve 62 that is attached to the side 10c of the cylinder block and adjusts the flow amount of the blow-by gas according to the pressure of the intake pipe 15 and the like, a PCV valve cover 65 that is disposed coaxially with the PCV valve 62 and is attached to the side 10c of the cylinder block so as to cover the PCV valve 62, and a PCV hose 61 that is connected to the PCV valve cover 65 and communicates the PCV valve cover 65 with the intake pipe 15 and the like. The PCV valve cover 65 is formed such that the inner diameter on the distal end side from a plane including the distal end surface of the PCV valve 62 is larger than the inner diameter on the proximal end side from the plane.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a blow-by gas treatment device. [Background technology]

[0002] Conventionally, blow-by gas treatment devices have been widely used to prevent blow-by gas that has leaked into the crankcase from between the cylinder and piston from being released into the environment (atmosphere), by returning the blow-by gas to the engine's intake system and burning it (see, for example, Patent Document 1).

[0003] The blow-by gas treatment device is configured to have, for example, a scavenging line (PCV line) that connects the inside of the crankcase with the downstream side of the throttle valve and introduces (recirculates) the blow-by gas into the intake system, a PCV (Positive Crankcase Ventilation) valve that adjusts the flow rate of the blow-by gas flowing through the scavenging line, and a fresh air line that connects the upstream side of the throttle valve with the inside of the crankcase and introduces fresh air.

[0004] Incidentally, for example, North American OBD2 (On Board Diagnostics Second Generation) requires that the PCV valve not come loose and that if the PCV valve does come loose, it must be possible to detect that it has come loose. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-173548 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, if a cover is provided to prevent the PCV valve from being removed from the cylinder block in order to comply with the above-mentioned regulations, for example, a liquid (hereinafter referred to as "turbid liquid") consisting of a mixture of oil contained in the blow-by gas and condensed water formed when the moisture (water vapor) contained in the blow-by gas condenses can accumulate between the PCV valve and the cover. When the vehicle accelerates, decelerates, or turns, the longitudinal acceleration (longitudinal G) and lateral acceleration (lateral G) cause the liquid level to tilt, and if the turbid liquid flows into the PCV valve in a mass, it can be sucked into the engine along with the flow of blow-by gas, potentially causing a deterioration in engine combustion.

[0007] The present invention has been made to solve the above problems, and aims to provide a blow-by gas treatment device that can comply with legal regulations regarding PCV valve detachment and that can prevent (or suppress) a turbid liquid, such as a mixture of oil contained in blow-by gas and condensed water generated by condensation of moisture contained in blow-by gas, from flowing all at once into the PCV valve. [Means for solving the problem]

[0008] A blow-by gas treatment device according to one embodiment of the present invention is a blow-by gas treatment device that connects the crankcase to the downstream side of the throttle valve of the intake system and introduces blow-by gas into the intake system, and includes: a PCV valve that is attached to the cylinder block and adjusts the flow rate of blow-by gas according to the pressure of the intake system; a PCV valve cover that is arranged coaxially with the PCV valve and is attached to the cylinder block so as to cover the PCV valve; and a PCV hose that is connected to the PCV valve cover and connects the PCV valve cover to the intake system, and is characterized in that the inner diameter of the PCV valve cover from a plane including the tip surface of the PCV valve is larger on the tip side than the inner diameter from the plane including the tip surface of the PCV valve on the base end side.

[0009] In one aspect of the blow-by gas treatment device of the present invention, the PCV valve cover is disposed coaxially with the PCV valve, is attached to the cylinder block so as to cover the PCV valve, and has an inner diameter on the tip side from a plane including the tip surface of the PCV valve that is larger than the inner diameter on the base side from that plane. Therefore, when the liquid level of the turbid liquid tilts due to longitudinal acceleration (longitudinal G) or lateral acceleration (lateral G) during acceleration / deceleration or turning of the vehicle, a portion of the turbid liquid (liquid level) (the turbid liquid on the upper surface) flows into the expanded diameter portion, lowering the liquid level and preventing (or suppressing) the turbid liquid from flowing into the PCV valve. [Effects of the Invention]

[0010] According to the present invention, it is possible to comply with legal regulations regarding the disconnection of the PCV valve, and also to prevent (or suppress) a turbid liquid, which is a mixture of oil contained in the blow-by gas and condensed water generated by condensation of the moisture contained in the blow-by gas, from flowing into the PCV valve all at once. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing the configuration of an engine to which a blow-by gas treatment device according to a first embodiment is applied. [Figure 2] 1 is a cross-sectional view showing the configuration of a main part of a blow-by gas treatment device according to a first embodiment. [Figure 3] FIG. 6 is a cross-sectional view showing the configuration of a main part of a blow-by gas treatment device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Unless otherwise specified, the same or corresponding parts in the drawings will be designated by the same reference numerals. Furthermore, the same elements in each drawing will be designated by the same reference numerals, and redundant explanations will be omitted.

[0013] (First embodiment) First, the configuration of a blow-by gas treatment device 60 according to the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a diagram showing the configuration of an engine 10 to which the blow-by gas treatment device 60 is applied. Figure 2 is a cross-sectional view showing the configuration of essential parts of the blow-by gas treatment device 60 (such as a PCV valve 62 and a PCV valve cover 65).

[0014] The engine 10 may be of any type, for example, a horizontally opposed four-cylinder gasoline engine. The engine 10 is a direct injection engine that injects fuel directly into the cylinders. In the engine 10, air taken in through an air cleaner 16 is throttled by an electronically controlled throttle valve (hereinafter simply referred to as a "throttle valve") 13 provided in an intake pipe 15, passes through an intake manifold 11, and is taken into each cylinder formed in the engine 10. The intake pipe 15 and the intake manifold 11 correspond to an intake system recited in the claims.

[0015] The amount of air taken in through the air cleaner 16 is detected by an air flow meter 14 disposed between the air cleaner 16 and the throttle valve 13. A vacuum sensor 30 is disposed inside a collector (surge tank) that constitutes the intake manifold 11 to detect the pressure inside the intake manifold 11 (intake manifold pressure). A throttle opening sensor 31 is disposed in the throttle valve 13 to detect the opening of the throttle valve 13.

[0016] The cylinder head is formed with an intake port 22 and an exhaust port 23 for each cylinder (only one bank is shown in FIG. 1). Each intake port 22 and exhaust port 23 is provided with an intake valve 24 and an exhaust valve 25 that open and close the intake port 22 and exhaust port 23, respectively. A variable valve timing mechanism 26 is disposed between the intake camshaft that drives the intake valve 24 and the intake cam pulley. The variable valve timing mechanism 26 rotates the intake cam pulley and the intake camshaft relatively to continuously change the rotational phase (displacement angle) of the intake camshaft with respect to the crankshaft 10a, thereby advancing or retarding the valve timing (opening / closing timing) of the intake valve 24. The variable valve timing mechanism 26 variably sets the opening and closing timing of the intake valve 24 according to the engine operating conditions.

[0017] Similarly, a variable valve timing mechanism 27 is disposed between the exhaust camshaft and the exhaust cam pulley, which rotates the exhaust cam pulley and the exhaust camshaft relatively to continuously change the rotational phase (displacement angle) of the exhaust camshaft with respect to the crankshaft 10a, thereby advancing or retarding the valve timing (opening / closing timing) of the exhaust valve 25. The variable valve timing mechanism 27 variably sets the opening / closing timing of the exhaust valve 25 according to the engine operating state.

[0018] An injector 12 that injects fuel into the cylinder is attached to each cylinder of the engine 10. The injector 12 directly injects fuel pressurized by a high-pressure fuel pump (not shown) into the combustion chamber of each cylinder.

[0019] The cylinder head of each cylinder is also fitted with a spark plug 17 that ignites the air-fuel mixture, and an igniter-integrated coil 21 that applies high voltage to the spark plug 17. In each cylinder of the engine 10, the air-fuel mixture of intake air and fuel injected by the injector 12 is ignited by the spark plug 17 and combusted. Exhaust gas after combustion is discharged through an exhaust pipe 18.

[0020] An air-fuel ratio sensor 19 is attached downstream of the collecting portion of the exhaust pipe 18 and upstream of the exhaust purification catalyst 20. As the air-fuel ratio sensor 19, a linear air-fuel ratio sensor (LAF sensor) is used which can output a signal corresponding to the oxygen concentration and unburned gas concentration in the exhaust gas (i.e., a signal corresponding to the air-fuel ratio of the mixture) and can linearly detect the air-fuel ratio.

[0021] An exhaust purification catalyst 20 is disposed downstream of the LAF sensor 19. The exhaust purification catalyst 20 is a three-way catalyst that simultaneously oxidizes hydrocarbons (HC) and carbon monoxide (CO) in the exhaust gas and reduces nitrogen oxides (NOx), converting harmful gas components in the exhaust gas into harmless carbon dioxide (CO2), water vapor (H2O), and nitrogen (N2). A silencer (muffler) 43 is attached downstream of the exhaust purification catalyst 20 to reduce exhaust noise.

[0022] An exhaust gas recirculation device (hereinafter referred to as an "EGR (Exhaust Gas Recirculation) device") 40 is provided in the exhaust pipe 18, which recirculates a portion of the exhaust gas emitted from the engine 10 to the intake manifold 11 of the engine 10. The EGR device 40 has an EGR pipe 41 that connects the exhaust pipe 18 of the engine 10 with the intake manifold 11, and an EGR valve 42 that is installed in the EGR pipe 41 and adjusts the amount of exhaust gas recirculation (EGR flow rate). The opening degree (EGRSTP) of the EGR valve 42 is controlled by an electronic control device 50, which will be described later, in accordance with the operating state of the engine 10.

[0023] In addition to the air flow meter 14, LAF sensor 19, vacuum sensor 30, and throttle opening sensor 31 described above, a cam angle sensor 32 for identifying the cylinders of the engine 10 is attached near the camshaft of the engine 10. A crank angle sensor 33 for detecting the rotational position of the crankshaft 10a is attached near the crankshaft 10a of the engine 10. A timing rotor 33a having, for example, 34 protrusions with two teeth missing, formed at 10° intervals, is attached to the end of the crankshaft 10a. The crank angle sensor 33 detects the rotational position of the crankshaft 10a by detecting the presence or absence of the protrusions on the timing rotor 33a. The cam angle sensor 32 and the crank angle sensor 33 may be, for example, electromagnetic pickup types.

[0024] These sensors are connected to an electronic control unit (hereinafter referred to as "ECU") 50. In addition, various sensors are also connected to the ECU 50, such as a water temperature sensor 34 that detects the temperature of the coolant for the engine 10, an oil temperature sensor 35 that detects the temperature of the lubricating oil, an accelerator sensor 36 that detects the amount of depression of the accelerator pedal, i.e., the amount of operation of the accelerator pedal, and a vehicle speed sensor 37 that detects the speed of the vehicle.

[0025] The ECU 50 is configured to include a microprocessor that performs calculations, an EEPROM that stores programs and the like for causing the microprocessor to execute various processes, a RAM that stores various data such as calculation results, a backup RAM in which the stored contents are maintained by a battery or the like, and an input / output I / F, etc. The ECU 50 also includes an injector driver that drives the injector 12, an output circuit that outputs an ignition signal, and a motor driver that drives the electric motor 13a that opens and closes the electronically controlled throttle valve 13, etc.

[0026] The ECU 50 identifies the cylinder from the output of the cam angle sensor 32, and determines the rotational angular velocity and engine speed from the output of the crank angle sensor 33. The ECU 50 also acquires various information such as the intake air amount, intake pipe negative pressure, accelerator pedal opening, air-fuel ratio of the mixture, and water temperature and oil temperature of the engine 10 based on the detection signals input from the various sensors described above. The ECU 50 then comprehensively controls the engine 10 by controlling the fuel injection amount, ignition timing, and various devices such as the throttle valve 13 and the EGR valve 42 based on the acquired information.

[0027] The engine 10 also includes a blow-by gas treatment device 60 that introduces blow-by gas leaking into the crankcase 10b from the combustion chamber through between the cylinder and the piston into the intake pipe 15 or the like (intake system) and combusts it.

[0028] The blow-by gas treatment device 60 is connected to a PCV valve cover 65 described later, and is configured to include a PCV hose (scavenging line) 61 that connects the PCV valve cover 65 to the downstream side of the throttle valve 13 of the intake pipe 15, etc., and introduces (recirculates) the blow-by gas into the intake pipe 15, etc., a PCV valve 62 (flow control valve) that is attached to the cylinder block 10c and adjusts the flow rate of the blow-by gas flowing through the PCV hose 61 depending on the pressure of the intake pipe 15, etc., and a fresh air hose (fresh air line) 63 that connects the upstream side of the throttle valve 13 to the inside of the crankcase 10b and introduces fresh air.

[0029] In this embodiment, the PCV valve 62 is of a type that operates according to the pressure difference between the crankcase 10b and the downstream side of the throttle valve 13 (e.g., the intake manifold 11). More specifically, the PCV valve 62 has, for example, a cylindrical housing, and within the housing are disposed a valve element that is slidable in the axial direction and a spring member that biases the valve element in a valve closing direction (downward). The valve element is formed in a generally rod-like shape, and its tip (upper end) is tapered and reduced in diameter. The tip is inserted into a through-hole in a plate provided at the tip of the valve. The valve element is configured to slide in the axial direction (up and down) in accordance with the balance between the negative pressure in the intake pipe and the spring force of the spring member. The flow path cross-sectional area changes depending on the position of the valve element, thereby adjusting the flow rate of blow-by gas passing through the PCV valve 62.

[0030] A hexagonal flange is provided on the outer periphery of the housing of the PCV valve 62, and the outer periphery of the lower side of the housing is threaded so that it can be screwed into a threaded hole in the cylinder block 10c.

[0031] In particular, the blow-by gas treatment device 60 according to this embodiment is compliant with legal regulations regarding the disconnection of the PCV valve 62, and has the function of preventing (or suppressing) the flow of a turbid liquid, such as a mixture of oil contained in the blow-by gas and condensed water produced by condensation of the moisture contained in the blow-by gas, into the PCV valve 62.

[0032] For this reason, the blow-by gas treatment device 60 is equipped with a PCV valve cover 65. The PCV valve cover 65 is disposed coaxially with the PCV valve 62 and is attached to the cylinder block 10c so as to cover the entire surface of the PCV valve 62. Therefore, the PCV valve 62 cannot be removed unless the PCV valve cover 65 is removed.

[0033] Furthermore, the inner diameters (cross-sectional areas) of the PCV valve cover 65 and the PCV hose 61 are set so that the engine 10 stops when the PCV valve cover 65 is removed, or the engine 10 cannot be started with the PCV valve cover 65 removed. That is, when the PCV valve cover 65 is removed, air is drawn in through the PCV valve cover 65 and the PCV hose 61 (note that the amount of air cannot be detected by the air flow meter 14 because the air is drawn in from the downstream side of the throttle valve 13), causing the air-fuel ratio to become extremely lean, resulting in a misfire. This allows an operator or the like to recognize that the PCV valve cover 65 (PCV valve 62) has been removed, thereby complying with the above-mentioned OBD2 and other legal regulations.

[0034] On the other hand, in order to reliably stop the engine 10 when the PCV valve cover 65 is removed, the inner diameter of the PCV valve cover 65 needs to be relatively large (for example, several tens of mm), which creates a gap between the PCV valve 62 and the PCV valve cover 65, allowing turbid liquid such as oil and condensed water to accumulate.

[0035] Therefore, when the PCV valve cover 65 is attached to the cylinder block 10c, the inner diameter (horizontal cross-sectional area) on the tip side (vertically upward) from a plane including the end face of the tip portion (opening) of the PCV valve 62 is formed (set) to be larger than the inner diameter (horizontal cross-sectional area) on the base end side (vertically downward) from the plane including the end face of the tip portion (opening) of the PCV valve 62. In other words, the PCV valve cover 65 is configured to have a base end 65a that covers the side surface of the PCV valve 62 at a distance, and an expanded diameter portion 65b that is formed on the tip side from the plane including the tip surface of the PCV valve 62 and has a larger diameter (expanded diameter) than the base end 65a.

[0036] The PCV valve cover 65 preferably has a base end (reduced diameter portion) 65a and an expanded diameter portion 65b each formed in, for example, a cylindrical shape. However, the PCV valve cover 65 may also be formed in a rectangular tubular shape (for example, a rectangular tubular shape having a regular hexagonal cross section). A nipple-shaped joint (mounting portion) onto which the PCV hose 61 is fitted is protruded from the top surface (upper end surface) of the PCV valve cover 65 (expanded diameter portion 65b).

[0037] The PCV valve cover 65 has a flange 65c with bolt mounting holes (through holes) formed on the outer periphery of the lower end of the base end 65a, and is fastened to the cylinder block 10c with bolts. The PCV valve 62 and the PCV valve cover 65 are each attached to the upper surface (top surface) of the cylinder block 10c so that their axes are parallel to the vertical direction.

[0038] The PCV valve cover 65 is preferably made of a metal (such as aluminum or iron) that has excellent thermal conductivity. However, the PCV valve cover 65 may be made of a material such as resin (engineering plastic). The PCV valve cover 65 can also be manufactured by, for example, a casting method using a core, a method of joining parts that are made separately for the base end portion 65a and the expanded diameter portion 65b, or a method of carving out the center (expanded diameter portion 65b) by machining.

[0039] By being configured as described above, that is, by setting the inner diameter (cross-sectional area) of the PCV valve cover 65 and the PCV hose 61 so that the engine 10 stops when the PCV valve cover 65 is removed or the engine 10 cannot be started with the PCV valve cover 65 removed, when the PCV valve cover 65 is removed, air is drawn in through the PCV valve cover 65 and the PCV hose 61, causing the air-fuel ratio to become extremely lean and resulting in a misfire. Therefore, an operator or the like can recognize that the PCV valve cover 65 (PCV valve 62) has come off.

[0040] The PCV valve cover 65 is disposed coaxially with the PCV valve 62 and is attached to the cylinder block 10c so as to cover the entire surface of the PCV valve 62. Therefore, as shown by the dashed line in FIG. 2, turbid liquid can accumulate up to the tip surface of the PCV valve 62. When acceleration (G) is applied in this state, the liquid level will tilt, as shown by the solid line in FIG. 2. Here, the PCV valve cover 65 is formed (set) so that the inner diameter (horizontal cross-sectional area) on the tip side (vertically upward side) from a plane including the end face of the tip portion (opening) of the PCV valve 62 is larger than the inner diameter (horizontal cross-sectional area) on the base side (vertically downward side) from that plane. Therefore, when the vehicle accelerates, decelerates, or turns, if the longitudinal acceleration (longitudinal G) or lateral acceleration (lateral G) causes the liquid level of the turbid liquid to tilt as shown by the solid line in Figure 2, a portion of the turbid liquid (liquid level) (the turbid liquid on the upper surface) will flow into the expanded diameter portion 65b, causing the liquid level of the turbid liquid to drop and preventing (or suppressing) the flow of the turbid liquid into the PCV valve 62.

[0041] As described above in detail, according to this embodiment, when the PCV valve cover 65 is removed, air is drawn in through the PCV valve cover 65 and the PCV hose 61, causing the air-fuel ratio to become extremely lean, resulting in a misfire. This allows an operator or the like to recognize that the PCV valve cover 65 (PCV valve 62) is removed, thereby complying with regulations such as OBD2. Furthermore, if the liquid level of the turbid liquid tilts due to longitudinal acceleration (longitudinal G) or lateral acceleration (lateral G) during acceleration, deceleration, or turning of the vehicle, a portion of the turbid liquid (liquid level) (the turbid liquid on the upper surface) flows into the expanded diameter portion 65b, lowering the liquid level and preventing (or suppressing) the turbid liquid from flowing into the PCV valve 62.

[0042] As a result, it is possible to comply with legal regulations regarding the disconnection of the PCV valve 62, and it is also possible to prevent (or suppress) a turbid liquid, such as a mixture of oil contained in the blow-by gas and condensed water generated by condensation of moisture contained in the blow-by gas, from flowing all together into the PCV valve 62.

[0043] Furthermore, according to this embodiment, the base end (reduced diameter portion) 65a and the expanded diameter portion 65b of the PCV valve cover 65 are each formed in a cylindrical (or rectangular tube) shape, and the PCV valve 62 and the PCV valve cover 65 are each attached to the upper surface (top surface) of the cylinder block 10c so that their axes are parallel to the vertical direction. This makes it possible to respond to accelerations in all directions (forward and backward acceleration (forward and backward G) and lateral acceleration (lateral G)), i.e., to appropriately prevent the inflow of turbid liquid.

[0044] (Second embodiment) Incidentally, the PCV valve cover 65 according to the first embodiment described above includes the base end 65a and the expanded diameter portion 65b, which have different inner diameters. Therefore, during manufacturing, for example, a core must be used during casting, the part must be divided into two parts, the base end 65a and the expanded diameter portion 65b, or the center (expanded diameter portion 65b) must be carved out by machining, which tends to increase the number of manufacturing steps and costs. Furthermore, among acceleration G, deceleration G, and turning G (lateral G), deceleration G tends to be the largest. That is, the amount of turbid liquid flowing into the PCV valve 62 tends to increase during deceleration (the amount of turbid liquid flowing in increases).

[0045] Therefore, in order to simplify the manufacture of the PCV valve cover 65, the volume on the vehicle front side (in the deceleration G direction) may be increased and the shape (structure) may be free of undercuts, in comparison with the first embodiment described above.

[0046] Next, a blow-by gas treatment device 60D according to a second embodiment will be described with reference to Fig. 3. Fig. 3 is a cross-sectional view showing the configuration of the main parts (PCV valve 62, PCV valve cover 65D, etc.) of the blow-by gas treatment device 60D. Note that in Fig. 3, components that are the same as or equivalent to those in the first embodiment are denoted by the same reference numerals.

[0047] The PCV valve cover 65D is formed in a tubular shape (for example, a cylindrical shape or a rectangular cylindrical shape) and is attached to the cylinder block 10c so as to cover the entire surface of the PCV valve 62. Here, the PCV valve cover 65D preferably has a circular cross section (horizontal cross section). However, the PCV valve cover 65D may have a cross section (horizontal cross section) that is oval, elliptical, egg-shaped, or the like.

[0048] In particular, the PCV valve cover 65D is attached with its central axis offset toward the front of the vehicle (in the deceleration G direction) with respect to the central axis of the PCV valve 62 (see the dashed line in FIG. 3). Therefore, the volume on the front side of the vehicle is larger than the volume on the rear side of the vehicle.

[0049] The other configurations are the same as or similar to the PCV valve cover 65 (first embodiment) described above, so detailed description thereof will be omitted here.

[0050] According to this embodiment, the formation of the expanded diameter portion 65b is unnecessary, thereby reducing the number of manufacturing steps and manufacturing costs. Furthermore, the central axis of the PCV valve cover 65D is offset toward the front of the vehicle (deceleration G side) with respect to the central axis of the PCV valve 62, so that the volume on the front side of the vehicle is larger than the volume on the rear side of the vehicle. Therefore, as shown by the solid line in FIG. 3, if the turbid liquid is biased toward the front of the vehicle (if the liquid level of the turbid liquid tilts) during vehicle deceleration, the liquid level of the turbid liquid drops, thereby preventing (suppressing) the inflow of the turbid liquid into the PCV valve 62 due to deceleration G.

[0051] Furthermore, acceleration G and turning G (lateral G) are relatively small compared to deceleration G, so the inclination of the liquid surface is small and the amount of turbid liquid flowing in is small, so the inflow of turbid liquid can be kept within an acceptable range.

[0052] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible. For example, although the above embodiment has been described using an example in which the present invention is applied to a naturally aspirated (NA) engine, the present invention can also be applied to an engine equipped with a supercharger (turbocharger, etc.).

[0053] Furthermore, in the above embodiment, a gasoline engine fueled by gasoline has been described as an example, but the present invention can also be applied to, for example, a hydrogen engine fueled by hydrogen, a diesel engine fueled by light oil, etc.

[0054] Furthermore, although the above embodiment has been described using an example in which the present invention is applied to a conventional gasoline engine vehicle, the present invention can also be applied to engines such as hybrid electric vehicles (HEVs) that have an engine and an electric motor as driving power sources. [Explanation of symbols]

[0055] 10 Engine 10a crankshaft 10b crankcase 10c cylinder block 11 Intake manifold 13 Electronically controlled throttle valve 15 Intake pipe 18 Exhaust pipe 19 Air-fuel ratio sensor 20 Exhaust purification catalyst 40 Exhaust Gas Recirculation System 41 EGR piping 42 EGR valve 43 Silencer 50 ECU 60, 60D Blow-by gas treatment device 61 PCV hose (scavenging line) 62 PCV valve 63 Fresh air hose (fresh air line) 65, 65D PCV valve cover 65a Base end (reduced diameter part) 65b Expanded diameter part 65c flange

Claims

1. A blow-by gas treatment device that communicates a crankcase with a downstream side of a throttle valve in an intake system and introduces blow-by gas into the intake system, a PCV valve attached to a cylinder block and adjusting the flow rate of blow-by gas according to the pressure of the intake system; a PCV valve cover that is disposed coaxially with the PCV valve and is attached to a cylinder block so as to cover the PCV valve; a PCV hose connected to the PCV valve cover and communicating the PCV valve cover with the intake system, The PCV valve cover is formed so that an inner diameter on the tip side from a plane including a tip surface of the PCV valve is larger than an inner diameter on the base end side from a plane including the tip surface of the PCV valve.

2. 2. The blow-by gas treatment device according to claim 1, wherein the PCV valve cover has a base end portion and an expanded diameter portion having an inner diameter larger than that of the base end portion, each of which is formed in a cylindrical or rectangular tubular shape.

3. A blow-by gas treatment device that communicates a crankcase with a downstream side of a throttle valve in an intake system and introduces blow-by gas into the intake system, a PCV valve attached to a cylinder block and adjusting the flow rate of blow-by gas according to the pressure of the intake system; a cylindrical PCV valve cover attached to a cylinder block so as to cover the PCV valve; a PCV hose connected to the PCV valve cover and communicating the PCV valve cover with the intake system, The blow-by gas treatment device is characterized in that the central axis of the PCV valve cover is offset toward the front of the vehicle with respect to the central axis of the PCV valve.

4. 4. The blow-by gas treatment device according to claim 1, wherein the PCV valve and the PCV valve cover are attached to the upper surface of the cylinder block so that their axes are parallel to the vertical direction.

5. 5. The blow-by gas treatment device according to claim 4, wherein the inner diameter of the PCV valve cover is set so that the engine stops or becomes unable to start when the PCV valve cover is removed.

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