JPH0577523U - Blow-by gas passage structure of engine - Google Patents

Abstract

(57) [Abstract] [Purpose] In an OHV type engine, it prevents mixture and crossover of blow-by gas with scattered oil and return oil in the valve train, and separates oil in blow-by gas by a simple and inexpensive means. Improve efficiency. An oil separation chamber of at least one appropriate volume is provided between intake passages of each cylinder of an engine, and a blow-by gas passage, which is displaced upstream and downstream thereof, is communicated with the oil separation chamber, and the oil separation chamber is provided downstream. An inclined surface that slopes upward is provided, and the oil separation chamber or the blow-by gas passage and the intake passage are communicated with each other through an orifice. [Effect] The oil separation efficiency can be improved, and an increase in the number of cylinders can be dealt with relatively easily and inexpensively.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a blow-by gas passage in an engine having an OHV type valve operating mechanism, and more particularly to a blow-by gas passage structure for an engine suitable for separating and removing oil in the blow-by gas during a blow-by gas reduction process.

[0002]

[Prior Art]

 FIG. 3 shows an outline of a vertical section of an engine having a general OHV type valve mechanism. A crankshaft 20 is pivotally supported in a cylinder block 9a which forms a crankcase chamber 8a below, and a piston 22 is supported by a connecting rod 21 so as to be vertically slidable. The camshaft 23, the tappet 24 are arranged on the cylinder block 9a, and the fuel injection pump 25 and the like are also attached to the cylinder block 9a. A cylinder head 11a is mounted above the cylinder block 9a, and a valve operating mechanism including an intake / exhaust valve 26, a rocker arm 27, etc. is installed. An intake port 16 is formed in the cylinder head 11a. On the cylinder head 11a, a rocker bracket 12a that houses the valve mechanism and forms an intake passage 17 that communicates with the intake port 16 of the cylinder head 11a is placed. The head cover 14a is fixed to the rocker bracket 12a via a gasket 15a. An intake passage 13 communicating with the intake passage 17 is formed in the head cover 14a. An intake manifold 28 is connected to the head cover 14a. A fuel injection nozzle 29 connected to the fuel injection pump 25 is connected to the cylinder head 11a and injects fuel into the cylinder bore 34 of the cylinder block 9a. In addition, a push rod passage 31 and a push rod hole 32 are formed in the cylinder block 9a and the cylinder head 11a to allow the push rod 30 that is installed between the tappet 24 and the rocker arm 27 to pass therethrough. The lower side of the crankcase chamber 8a of the cylinder block 9a is closed by an oil pan 33.

In the engine having the above-described structure, a flow path of blow-by gas generated by combustion of the engine will be described. A part of the combustion gas generated by the combustion of the engine passes through the gap between the inner wall of the cylinder bore 34 and the outer periphery of the piston 22 and blows out to the crank case chamber 8a side, so-called blow-by gas. The blow-by gas passes through the space around the cam shaft 23 from the downstream crankcase chamber 8a side to rise in the push rod passage 31 and the push rod hole 32 as shown by the solid arrow in FIG. It penetrates into 12a. The blow-by gas that has entered the rocker bracket 12a passes through an oil separator (not shown) installed on the head cover 14a side, and passes through an orifice (not shown) that communicates with the intake passage 13 of the head cover 14a. It is introduced into the intake port 16 of the cylinder head 11a together with the air (shown by the thick arrow) that has entered the inside and is sucked from the intake manifold 28. On the other hand, oil for lubricating the valve mechanism and the like is introduced from the oil pan 33 side into the rocker bracket 12a. The spent oil in the rocker bracket 12a is pushed from the rocker bracket 12a side through the space around the rod rod 32 and the cam shaft 23 as shown by the dotted arrow in FIG. 3, and is returned to the lower oil pan 33. Is circulated. Therefore, as shown in FIG. 3, the blow-by gas and the return oil intersect within the push rod hole 32 and before and after the push rod hole 32. As a result, there is a problem that the flow of both blowby gas and oil becomes unsmooth. Further, a part of the return oil is mixed in the ascending blow-by gas, and the blow-by gas passes through the rocker bracket 12a filled with the scattered oil that scatters as the rocker arm 27 moves. A part of the scattered oil rides on the flow of blow-by gas and is guided to the intake passage 13 side. As described above, the head cover 14a is provided with an oil separator (not shown), but the oil is not introduced into the intake passages 13 and 17 and the intake port 16 without sufficient oil separation by the device alone. There is a problem that it burns in the cylinder, increases white smoke in the exhaust gas, and wastes oil.

Known techniques for separating and removing oil mixed in blow-by gas include, for example, those disclosed in Japanese Utility Model Publication No. 56-161109, Japanese Utility Model Publication No. 57-176611, and Japanese Utility Model Publication No. 63-158515. Can be raised. The breather device disclosed in Japanese Utility Model Laid-Open No. 56-161109 forms a breather chamber in a part of the head cover, and separates oil in blow-by gas with an oil separation material such as steel wool filled in the breather chamber. The blow-by gas separated from the oil is introduced to the intake manifold side that communicates with the breather chamber through the gas suction holes. The blow-by gas suction device disclosed in Japanese Utility Model Publication No. 57-176611 has a cylinder head cover (corresponding to the rocker bracket 12a in FIG. 3 and formed adjacent to the intake port) which is attached to the intake port. An intake air passage communicating with each other is formed through a partition wall, and a small vent hole communicating with the intake air passage is formed above the partition wall. Further, the blow-by gas reduction device disclosed in Japanese Utility Model Laid-Open No. 63-585515 has a blow-by gas passage penetrating between the crankcase chamber side of the cylinder block and the intake passage, and a labyrinth type oil separation device is provided in the blowby gas passage. And a PCV valve. The PCV valve allows blow-by gas to pass according to the pressure difference between the internal pressure (negative pressure) of the intake passage and the internal pressure of the crankcase chamber, and is returned to the suction passage side during a low load such as idle operation. It limits the flow rate of blow-by gas.

[0005]

[Problems to be solved by the device]

 In the case of the engine shown in FIG. 3 and those shown in Japanese Utility Model Laid-Open Nos. 56-161109 and 57-176611, as described above, the rising blowby gas and the returning return oil cross each other on the way. Therefore, there is a problem that the flow of the two cannot be carried out smoothly. Further, since the scattered oil in the valve operating mechanism comes into contact with the blow-by gas, the scattered oil mixes into the blow-by gas and the passage between the storage chamber of the valve operating mechanism and the suction passage cannot be long, so the oil separation device However, there is a problem that the oil in blow-by gas cannot be separated sufficiently. On the other hand, the blow-by gas reduction device disclosed in Japanese Utility Model Laid-Open No. Sho 63-1581515 forms a blow-by gas passage in the walls of the cylinder block, cylinder head, intake manifold, etc. There is no crossover with and no contact with splashed oil. However, even in this case, there are the following problems. In the case of a general-purpose engine, the basic structure such as cylinder bore and stroke is the same, and it is often the case that an engine series is made by increasing or decreasing the number of cylinders. As the number of cylinders increases, so does the displacement, so it is necessary to increase the blow-by gas passages. In that case, changing the sizes of the oil separator and the PCV valve is not preferable in terms of processing, sharing of parts, and expansion of space. Therefore, it is possible to increase the number of oil separators and PCV valves of the same shape according to the number of cylinders. However, the labyrinth-type oil separator and the PCV valve have a relatively complicated structure, which greatly increases the cost. On the other hand, in the case of this known technique, the PCV valve itself does not directly function for oil separation in blow-by gas, but only the labyrinth type oil separator functions for oil separation. However, as shown in FIGS. 4-6, oil separation of this type is not sufficient. That is, as shown in FIG. 4, when blow-by gas mixed with oil is introduced into the oil separator 35, small-sized oil mist 37 adheres to the partition wall portion 36. As shown in FIG. 5, the small-sized oil mist 37 adhering to the partition wall portions 36 is pushed by the flow of blow-by gas flowing between the partition wall portions 36 and flows toward the tip of the partition wall portions 36, and sticks to each other, resulting in large particles. It grows to an oil mist 38. Next, as shown in FIG. 6, the large-grained oil mist 38 that has grown and adhered to the tip side of the partition wall portion 36 flies along with the flow of blow-by gas, and the oil is carried to the downstream side of the separator 35. It is transferred to the intake passage side together with blow-by gas. Due to the above, oil separation is not effectively performed in the labyrinth type oil separator 35.

The present invention solves each of the problems described above, and there is no crossover between blow-by gas and return oil, and there is little contact between scattered oil and blow-by gas, reducing the amount of oil mixed in blow-by gas. It is an object of the present invention to provide a blow big gas passage structure for an engine, which is capable of effectively performing oil separation, and can easily and inexpensively cope with an increase in the number of cylinders.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention has an OHV type valve operating mechanism including a cylinder block, a cylinder head, a rocker bracket, and a head cover, and the intake of the head cover on the upstream crankcase side and the downstream side of the engine. A blow-by gas passage structure communicating between the passages, wherein at least one oil separation chamber of an appropriate volume and a blow-by gas passage that is displaced and connected upstream and downstream of the separation chamber are connected between the intake passages of each cylinder. The blow-by gas passage structure of the engine to be formed is formed, and an orifice is formed at a portion of the oil separation chamber or the blow-by gas passage communicating with the inside of the head cover, and the oil separation chamber is inclined upward toward the downstream side. The blow-by gas passage structure of the engine is formed by forming an inclined surface.

[0008]

[Action]

 The blow-by gas blown to the crankcase chamber side rises in the blow-by gas passage formed in the cylinder block, cylinder head, and the like. Since the return oil from the valve mechanism does not pass through the blow-by gas passage, the blow-by gas does not cross the return oil. The blow-by gas enters the oil separation chamber of an appropriate volume from the upstream blow-by gas passage and expands, and then rises in the blow-by gas passage on the downstream side which is displaced and communicates with the oil separation chamber. At that time, the oil mixed in the blow-by gas is separated. The oil in the blow-by gas is sufficiently separated and removed by providing the oil-separation chamber and a plurality of blow-by gas passages on the upstream and downstream sides that communicate with each other by being displaced from each other. In addition, since the oil separation chamber has an inclined surface that rises toward the downstream side, when the blow-by gas contacts and passes through the inclined surface, the oil in the blow-by gas adheres to the inclined surface and moves toward the upstream side. Are dropped and removed. Further, the blow-by gas is introduced into the intake passage side while being throttled by the orifice to separate the oil. As described above, the blow-by gas that has been sufficiently oil-separated is introduced to the intake passage side. Further, when the number of cylinders increases, the blow-by gas passage or the like may be increased accordingly, which is relatively easy. Further, in many cases, a cavity for removing the meat is formed in advance in the cylinder block, the rocker bracket, etc., so that the cavity can be used for the oil separation chamber.

[0009]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view of an engine having an OHV type valve operating mechanism to which the present embodiment is applied, and FIG. 2 is an enlarged partial vertical sectional view showing a detailed structure of a main part of the same embodiment. In FIG. 1, a cylinder head 11 is fixed by a cylinder head tightening bolt 10 on a cylinder block 9 forming a crankcase chamber 8. A rocker bracket 12 in which a valve mechanism (not shown) is housed is mounted on the cylinder head 11, and a head cover 14 forming an intake passage 13 is fixed above the rocker bracket 12 via a gasket 15. The intake passage 13 communicates with the intake passage 17 of the rocker bracket 12 and the intake port 16 of the cylinder head 11, as shown in FIG. Note that FIG. 1 is a vertical cross-sectional view at a position of a cylinder head tightening bolt 10 between cylinders, which is different in cross-sectional position from FIG.

Next, the structure of the blow-by gas passage through which the blow-by gas passes will be described with reference to FIGS. 1 and 2. The blow-by gas passage is formed between the intake passages of each cylinder. In this embodiment, an oil separation chamber having two oil separation chambers, a first oil separation chamber 1 and a second oil separation chamber 2, is adopted. The first oil separation chamber 1 is formed by combining the concave groove 1a formed on the uppermost surface of the cylinder block 9 and the concave groove 1b formed on the lowermost surface of the cylinder head 11 at a position opposite to the concave groove 1a. The cylinder block 9 and the cylinder head 11 which are previously formed at the time of casting are used. The second oil separation chamber 2 is composed of a chamber 18 for accommodating a valve operating mechanism (not shown) and a concave portion defined by a partition wall 19, and the concave portion is opened on the lowermost surface side of the rocker bracket 12. Formed. Further, an upper wall portion 6 through which the orifice 3 is formed is formed on the upper side of the concave portion. A first blow-by gas passage 4 and a second blow-by gas passage 5 are connected to the first oil separation chamber 1 and the second oil separation chamber 2. Since the first blow-by gas passage 4 is formed in the wall of the cylinder block 9, the lower end side of the drawing communicates with the crankcase chamber 8 and the upper end side communicates with the concave groove 1a of the first oil separation chamber 1. To do. On the other hand, the second blow-by gas passage 5 is formed in the wall of the cylinder head 11, its lower end communicates with the concave groove 1b of the first oil separation chamber 1, and its upper end enters the second oil separation chamber 2. Open. The first blow-by gas passage 4 faces the upstream blow-by gas passage, and the second blow-by gas passage 5 corresponds to the downstream blow-by gas passage. The portions where the first blow-by gas passage 4 and the second blow-by gas passage 5 open to the first oil separation chamber 1 are formed displaced by a distance a as shown in FIG. Further, as shown in FIG. 2, the portion of the second blow-by gas passage 5 that opens into the second oil separation chamber 2 and the orifice 3 are displaced by a distance b. The upper wall portion 6 of the orifice 3 of the second oil separation chamber 2 which is perforated is formed into an inclined surface 7 having an angle θ which inclines upward from the second blowby gas passage 5 side toward the orifice 3.

Next, the separating action of oil in the blow-by gas in the blow-by gas passage structure of the present embodiment will be described. The blow-by gas blown from the cylinder side to the crank case chamber 8 side enters the first blow-by gas passage 4 from the upstream crank case chamber 8 and rises as shown by the solid arrow in FIG. The blow-by gas in the first blow-by gas passage 4 enters the first oil separation chamber 1 and expands as shown in FIG. Due to the expansion, the flow velocity of the blow-by gas decreases and some of the oil mixed in the gas is separated. In addition, the oil adhering to the wall surface in the room is not transported to the downstream side due to the decrease in flow velocity. Since the first blow-by gas passage 4 and the second blow-by gas passage 5 on the downstream side are displaced from each other, the blow-by gas that has entered the first oil separation chamber 1 does not flow into the first oil separation chamber. It hits the upper surface of 1 and rises while bending and enters into the second blow-by gas passage 5. With the above operation, part of the oil in the blow-by gas is separated. Next, the blow-by gas that has risen in the second blow-by gas passage 5 enters the second oil separation chamber 2 and expands again to separate the oil. The blow-by gas from which the oil has been separated rises along the inclined surface 7 having an angle θ. At that time, the oil in the blow-by gas adheres to the upper wall portion 6. The adhered oil descends on the inclined surface 7 and does not proceed to the orifice 3 side. Further, the blow-by gas that has entered the second oil separation chamber 2 from the second blow-by gas passage 5 bends and enters the intake passage 13 of the head cover 14 through the orifice 3 that is separated by a distance b. Since the orifice 3 is formed by a small hole, the oil in the blow-by gas is further separated when passing through the orifice 3. As described above, the blowby gas from which most of the oil has been removed is introduced into the intake passage 13 of the head cover 14. Further, in the case of this embodiment, unlike the prior art, the amount of oil mixed in the blow-by gas is small from the beginning, but the oil is more reliably separated by passing through the above-mentioned blow-by gas passage structure. By installing an oil separation device (not shown) on the head cover 14 or the like, the oil separation of blow-by gas is almost completely performed.

In the above embodiment, two oil separation chambers are used as the first and second oil separation chambers 1 and 2, but the first and second oil separation chambers are used as cylinders in advance. Since the blocks 9, the cylinder heads 11 and the rocker brackets 12 that are formed during casting are used, the number is not limited to two. Further, the blow-by gas passages also employ the first and second blow-by gas passages 4 and 5, but are not limited thereto. Further, although the inclined surface 7 is formed only in the second oil separation chamber 2 in this embodiment, it may be formed in the first oil separation chamber 1 as a matter of course.

[0013]

[Effect of the device]

 According to the present invention, the following remarkable effects are obtained. (1) Since the blow-by gas passage is formed at a place unrelated to the return oil passage, it does not intersect with the return oil. Therefore, the blow-by gas and the return oil do not interfere with each other, and the two flows smoothly. (2) Since blow-by gas passing through the blow-by gas passage does not pass through the rocker bracket filled with scattered oil, scattered oil is not mixed. (3) The blow-by gas rises while being bent by the blow-by gas passages displaced from each other, and expands by the oil separation chamber. The expansion and bending action promotes oil separation in the blow-by gas, improving the oil separation efficiency compared to labyrinth type oil separators. (4) If the orifice is formed, the oil separation is further promoted. (5) If the inclined surface is formed in the oil separation chamber, the oil separation is further promoted. (6) The blow-by gas passage structure of the present invention is formed in the wall portion of the cylinder block or the like between the cylinders, and can easily cope with the increase in the number of cylinders. (7) Since the labyrinth type oil separator and the PCV valve are not used unlike the prior art, the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an engine having a blow-by gas passage structure according to an embodiment of the present invention.

FIG. 2 is an enlarged partial vertical sectional view showing details of the blow-by gas passage structure of the embodiment.

FIG. 3 is a vertical sectional view of a conventional engine.

FIG. 4 is an explanatory view for explaining an oil separating action in a labyrinth type oil separator.

FIG. 5 is an explanatory diagram for explaining a problem of an oil separating action of a labyrinth type oil separator.

FIG. 6 is an explanatory diagram for explaining a problem of an oil separating action of a labyrinth type oil separator.

[Explanation of symbols]

 1 1st oil separation chamber 2 2nd oil separation chamber 3 Orifice 4 1st blow-by gas passage 5 2nd blow-by gas passage 6 Upper wall part 7 Inclined surface 8 Crank case chamber 9 Cylinder block 10 Cylinder head tightening bolt 11 Cylinder Head 12 Rocker Bracket 13 Intake Passage 14 Head Cover 15 Gasket 16 Intake Port 17 Intake Passage 18 Chamber 19 Bulkhead 20 Crankshaft 21 Connecting Rod 22 Piston 23 Camshaft 24 Tappet 27 Rocker Arm 28 Intake Manifold 30 Push Rod 31 Push Rod Passage 32 Push Rod Hole 35 Oil separator 36 Partition wall 37 Oil mist 38 Oil mist

Claims (3)

[Scope of utility model registration request] 1. A blow-by gas passage communicating between an intake passage of an upstream crankcase side of an engine having an OHV type valve operating mechanism including a cylinder block, a cylinder head, a rocker bracket, a head cover and the like and a downstream side intake passage of the head cover. An engine characterized in that at least one oil separation chamber having an appropriate volume and a blow-by gas passage connected to the upstream and downstream sides of the separation chamber by being displaced from each other are formed between intake passages of respective cylinders. Blow-by gas passage structure. 2. The blowby gas passage structure for an engine according to claim 1, wherein an orifice is formed in a portion of the oil separation chamber or the blowby gas passage that communicates with the inside of the head cover. 3. The blow-by gas passage structure for an engine according to claim 1, wherein the oil separation chamber forms an inclined surface that inclines upward toward the downstream side.