Internal combustion engine

Abstract

The present invention provides an internal combustion engine that can smoothly recirculate the oil, which has been separated into gas and liquid components in the blow-by gas passage, back to the crankcase. [Solution] In the internal combustion engine EG according to the present invention, a second blow-by gas passage 15, which is bent and connected to the first blow-by gas passage 14 in the blow-by gas passage 13, is connected to the crankcase 12 via a return passage 16 provided separately from the first blow-by gas passage 14. Therefore, even if a large amount of oil is generated through gas-liquid separation in the second blow-by gas passage 15 or separator 7, the oil can be smoothly returned to the crankcase 12 via the return passage 16.

Description

Technical Field

[0001] The present invention relates to an internal combustion engine.

Background Art

[0002] As a conventional internal combustion engine, for example, the one described in Patent Document 1 below is known.

[0003] Briefly explained, in a conventional internal combustion engine, a first blow-by gas passage and a second blow-by gas passage extending in the vertical direction are connected via a third blow-by gas passage extending in the horizontal direction, and the first blow-by gas passage, the second blow-by gas passage, and the third blow-by gas passage are configured to bend in a crank shape.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the conventional internal combustion engine, due to the crank structure of the blow-by gas passage, the oil separated in the blow-by gas passage flows backward against the flow of the blow-by gas. As a result, there is still room for improvement in that the reflux of the oil separated in the blow-by gas passage to the crankcase may be hindered.

[0006] Therefore, the present invention has been devised in view of the technical problems related to the conventional internal combustion engine, and an object thereof is to provide an internal combustion engine capable of smoothly refluxing the oil separated by gas-liquid separation in the blow-by gas passage to the crankcase.

Means for Solving the Problems

[0007] An internal combustion engine according to the present invention, in one embodiment thereof, comprises a cylinder block in which a plurality of cylinders are arranged in parallel, a separator attached to the cylinder block and having a labyrinth structure formed between it and the cylinder block, and a blow-by gas passage provided in the cylinder block and guiding blow-by gas flowing in through a crankcase provided at the lower part of the cylinder block to the separator, wherein the blow-by gas passage includes an upstream first blow-by gas passage that opens into the crankcase, and a downstream second blow-by gas passage that bends with respect to the first blow-by gas passage downstream of the first blow-by gas passage and opens into the separator, and the second blow-by gas passage is connected to the crankcase via a return passage that branches off at a position closer to the separator than the first blow-by gas passage. [Effects of the Invention]

[0008] According to the present invention, in the blow-by gas passage, the second blow-by gas passage is connected to the crankcase via a return passage provided separately from the first blow-by gas passage. Therefore, even if a large amount of oil is generated through gas-liquid separation in the second blow-by gas passage or separator, this oil can be appropriately and smoothly returned to the crankcase via the return passage. As a result, the amount of oil guided from the separator to the intake side can be reduced compared to conventional internal combustion engines. [Brief explanation of the drawing]

[0009] [Figure 1] This is a system configuration diagram of the internal combustion engine according to the present invention. [Figure 2] Figure 1 is a schematic side view of an internal combustion engine. [Figure 3] This is a cross-sectional view along line AA in Figure 2. [Modes for carrying out the invention]

[0010] An embodiment of the internal combustion engine according to the present invention will be described in detail below with reference to the drawings. In the following embodiment, an example will be given in which the internal combustion engine according to the present invention is applied to a gasoline engine for an automobile.

[0011] Figure 1 shows a system configuration diagram of the internal combustion engine according to this embodiment. In Figure 1, the solid arrow C indicates the flow of blow-by gas, and the dashed arrow B indicates the flow of fresh air. Figure 2 shows a schematic diagram of the internal combustion engine shown in Figure 1, viewed from the side. Figure 3 shows a cross-sectional view taken along line AA in Figure 2.

[0012] For example, as shown in Figures 1 and 2, the internal combustion engine EG according to this embodiment is a spark-ignition engine equipped with a turbocharger, and comprises a cylinder block 1, a cylinder head 2 provided on the upper part of the cylinder block 1, a cylinder head cover 3 provided on the upper part of the cylinder head 2, and an oil pan 4 provided on the lower part of the cylinder head 2. The internal combustion engine EG is also provided with a front cover 5 that extends vertically across the cylinder block 1, cylinder head 2, cylinder head cover 3 and oil pan 4, and covers the front end of the internal combustion engine EG.

[0013] The cylinder block 1 has, inside its upper end, a plurality of cylinders (for example, three in this embodiment) consisting of a first cylinder C1, a second cylinder C2, and a third cylinder C3 (hereinafter collectively referred to as "cylinder 11") arranged in parallel in the front-rear direction of the internal combustion engine EG, each slidably housing a piston 9. The lower part of the cylinder block 1 also has a crankcase 12 that houses a crankshaft (not shown) which opens into each cylinder 11 and is connected to the piston 9.

[0014] The cylinder head 2 has a plurality of combustion chambers 20 inside its lower end, each opening into one of the cylinders 11. Above each combustion chamber 20, there is a well-known intake port (not shown) opened and closed by an intake valve 21, and a well-known exhaust port (not shown) opened and closed by an exhaust valve 22. Intake air, guided by an intake passage 6, is introduced into each intake port via an intake manifold 60 connected to the side of the cylinder head 2. Furthermore, the inside of the cylinder head 2 is in communication with the oil pan 4 and the crankcase 12 through the inside of a front cover 5 connected to the side (front end) of the cylinder head 2.

[0015] The intake passage 6 has an air cleaner 61 at its upstream inlet, and a turbocharger compressor 62 is located partway along the intake passage 6. A throttle valve 63 for controlling the amount of intake air to the internal combustion engine EG is also provided downstream of the compressor 62 in the intake passage 6. An intercooler 64 for cooling the intake air compressed by the compressor 62 is also provided between the compressor 62 and the throttle valve 63 in the intake passage 6.

[0016] The throttle valve 63 is a so-called electronically controlled throttle valve equipped with an electric actuator (not shown), such as a motor, and its opening degree is controlled by an engine controller (not shown). This throttle valve 63 is located upstream of the intake collector 601, which is the collector of the intake manifold 60, and multiple intake branch pipes 602 branch off from the intake collector 601 to each cylinder 11.

[0017] In addition, in the intake passage 6, a negative pressure generation valve 65 for generating a negative pressure in the region between the negative pressure generation valve 65 and the compressor 62 is provided upstream of the compressor 62. The negative pressure generation valve 65 has a butterfly valve type configuration similar to the throttle valve 63, and the opening degree is controlled by an engine controller (not shown) via an electric actuator (not shown) such as a motor so as to generate a necessary negative pressure according to the operating conditions of the internal combustion engine EG. That is, by providing this negative pressure generation valve 65, it is possible to generate a necessary negative pressure according to the operating conditions of the internal combustion engine EG and contribute to the appropriate recirculation of blow-by gas and EGR described later.

[0018] In the internal combustion engine EG, gas containing unburned components, that is, blow-by gas, leaks from the combustion chamber 20 of each cylinder through each cylinder 11 to the crankcase 12 side. This blow-by gas is guided into the separator 7 attached to the side of the cylinder block 1 through the blow-by gas passage 13 formed inside the cylinder block 1.

[0019] As shown in FIG. 2, for example, the blow-by gas passage 13 integrally includes a first blow-by gas passage 14 extending in the vertical direction and a second blow-by gas passage 15 connected to the first blow-by gas passage 14 and extending in the horizontal direction along the cylinder bank direction of the internal combustion engine EG.

[0020] The first blow-by gas passage 14 is provided upstream in the flow of blow-by gas, and the upstream end opens to the crankcase 12. At this time, the first blow-by gas passage 14 is connected to the crankcase 12 at a position outside the cylinder bank direction from the cylinder center Cx of the third cylinder C3, which is the cylinder located at the rear end in the cylinder bank direction (the right end in FIG. 2).

[0021] The second blow-by gas passage 15 is provided on the downstream side in the flow of blow-by gas. The upstream end of the second blow-by gas passage 15 is bent and connected to the downstream end of the first blow-by gas passage 14 at a substantially right angle with respect to the first blow-by gas passage 14, and the downstream end opens into the separator 7. Note that the second blow-by gas passage 15 may be connected to the first blow-by gas passage 14 at an obtuse angle or an acute angle in addition to the mode of being connected at the right angle as described above.

[0022] Thus, due to the fact that the second blow-by gas passage 15 is bent with respect to the first blow-by gas passage 14, the blow-by gas led from the crankcase 12 through the first blow-by gas passage 14 flows into the second blow-by gas passage 15, and a gas-liquid separation action for separating the gas (gas) and oil content contained in the blow-by gas is obtained.

[0023] Also, inside the cylinder block 1, a return passage 16 that branches from the second blow-by gas passage 15 is provided at a position closer to the separator 7 than the first blow-by gas passage 14 (for example, inside the separator 7 in this embodiment).

[0024] One end of the return passage 16, which is the upstream end in the flow of blow-by gas, opens into the inside of the separator 7 (the first separator chamber S1 to be described later) and is connected to the second blow-by gas passage 15 inside the separator 7, and the other end, which is the downstream end in the flow of blow-by gas, opens into the crankcase 12 at a position between cylinders in the cylinder row direction (for example, between the second cylinder C2 and the third cylinder C3 in this embodiment).

[0025] Here, regarding the return passage 16, it only needs to branch from the second blow-by gas passage 15 at a position closer to the separator 7 than the first blow-by gas passage 14, and is not limited to the mode disclosed in this embodiment of being connected to the second blow-by gas passage 15 inside the separator 7.

[0026] Furthermore, it is desirable that the cross-sectional area CS2 of the return passage 16 is set to be smaller than the cross-sectional area CS1 of the blow-by gas passage 13. However, if the cross-sectional areas CS1 and CS2 of the blow-by gas passage 13 and the return passage 16 are not constant, it is sufficient that the minimum cross-sectional area of ​​the return passage 16 is set to be smaller than the minimum cross-sectional area of ​​the blow-by gas passage 13.

[0027] Furthermore, it is desirable that the cross-sectional area CS2 of the return passage 16 is set to be smaller than the cross-sectional area CS3 of the bypass passage 23, which will be described later. If the cross-sectional areas CS2 and CS3 of the return passage 16 and the bypass passage 23 are not constant, it is sufficient that the minimum cross-sectional area of ​​the return passage 16 is set to be smaller than the minimum cross-sectional area of ​​the bypass passage 23.

[0028] As shown in Figures 1 to 3, for example, the separator 7 is formed in a generally box shape and attached to the outer surface 1a of the cylinder block 1. The inner surface 7a of the separator 7 is provided with a first protrusion 70 that extends horizontally toward the cylinder block 1 and whose tip is slightly separated from the outer surface 1a of the cylinder block 1.

[0029] On the other hand, the outer surface 1a of the cylinder block 1 facing the separator 7 is provided with a second protrusion 10 that extends horizontally toward the separator 7 and whose tip is slightly spaced apart from the inner surface 7a of the separator 7. The second protrusion 10 is provided slightly spaced apart (offset) from the first protrusion 70 so as to be arranged alternately with the first protrusion 70 in the vertical direction, as shown in Figure 3, for example.

[0030] Thus, a first separator chamber S1 is formed between the inner surface 7a of the separator 7 and the outer surface 1a of the cylinder block 1, with a labyrinth structure formed by a first protrusion 70 and a second protrusion 10 arranged alternately in the vertical direction, which serves to separate the gas and oil contained in the blow-by gas. In other words, this first separator chamber S1 with its labyrinth structure makes it possible to effectively separate the gas and oil contained in the blow-by gas introduced through the blow-by gas passage 13 (second blow-by gas passage 15).

[0031] Furthermore, the internal combustion engine EG is equipped with a blow-by gas recirculation system that returns blow-by gas to the intake passage 6 for recirculation, as shown in Figure 1, for example. This blow-by gas recirculation system includes a fresh air introduction pipe 81 that constitutes a fresh air introduction section for introducing fresh air into the crankcase 12, and a blow-by gas recirculation pipe 82 that guides blow-by gas to the upstream side of the compressor 62 in the intake passage 6.

[0032] In the embodiment shown in Figure 1, one end of the fresh air intake pipe 81, which is the upstream end in the fresh air flow, is connected upstream of the negative pressure generating valve 65 of the intake passage 6, and the other end, which is the downstream end in the fresh air flow, is connected to the cylinder head cover 3 of the internal combustion engine EG. The other end of the fresh air intake pipe 81 can also be connected to the cylinder head 2. In this way, fresh air is introduced into the space defined by the cylinder head cover 3 and the cylinder head 2, and the fresh air intake section according to the present invention is provided in the cylinder head cover 3 or the cylinder head 2.

[0033] The blow-by gas recirculation pipe 82 has one end, which is the upstream end in the blow-by gas flow, connected to the first separator chamber S1 of the internal combustion engine EG, and the other end, which is the downstream end in the blow-by gas flow, connected between the negative pressure generating valve 65 and the compressor 62 of the intake passage 6.

[0034] With this configuration, in the blow-by gas recirculation system, fresh air introduced by the fresh air introduction pipe 81 is guided through the inside of the cylinder head 2 into the inside of the front cover 5. The fresh air guided into the inside of the front cover 5 flows from the front cover 5 into the oil pan 4 and the crankcase 12 which opens into the oil pan 4, and ventilates (scavenges) the inside of the front cover 5 and the crankcase 12 by flowing through the inside of the crankcase 12 along the direction of the cylinder row. After that, the fresh air that has flowed through the inside of the crankcase 12 flows into the blow-by gas passage 13 together with the blow-by gas that has flowed into the crankcase 12 from each cylinder 11, and is guided through the blow-by gas passage 13 to the first separator chamber S1, and from the first separator chamber S1 it is recirculated through the blow-by gas recirculation pipe 82 to the intake passage 6.

[0035] Furthermore, a second chamber S2 is formed inside the cylinder head cover 3, for example, as shown in Figure 1. This second chamber S2 is in communication with the first separator chamber S1 via a bypass passage 23 that bypasses the crankcase 12 from the fresh air introduction pipe 81.

[0036] The bypass passage 23 is connected to the inside of the cylinder block 1 via the cylinder head 2 at the rear end of the cylinder head 2, as shown in Figure 2, for example, and introduces fresh air into the first separator chamber S1 through the inside of the cylinder head 2, bypassing the crankcase 12. In addition to the configuration in which fresh air is introduced into the first separator chamber S1 via the cylinder head 2 as in this embodiment, the bypass passage 23 may also be configured to bypass the fresh air introduction pipe 81 directly and connect to the inside of the cylinder block 1 without going through the cylinder head 2. In this case, the fresh air introduction section according to the present invention is provided in the cylinder block 1.

[0037] Furthermore, it is desirable that the cross-sectional area CS3 of the bypass passage 23 be set to be smaller than the cross-sectional area CS1 of the blow-by gas passage 13. If the cross-sectional areas CS1 and CS3 of the blow-by gas passage 13 and the bypass passage 23 are not constant, it is sufficient that the minimum cross-sectional area of ​​the bypass passage 23 be set to be smaller than the minimum cross-sectional area of ​​the blow-by gas passage 13.

[0038] (Effects of this embodiment) As described above, in the internal combustion engine EG according to this embodiment, the second blow-by gas passage 15, which is bent and connected to the first blow-by gas passage 14 in the blow-by gas passage 13, is connected to the crankcase 12 via a return passage 16 provided separately from the first blow-by gas passage 14. Therefore, even if a large amount of oil is generated through gas-liquid separation in the second blow-by gas passage 15 or separator 7, this oil can be appropriately and smoothly returned to the crankcase 12 via the return passage 16. As a result, the amount of oil guided from separator 7 to the intake side can be reduced compared to conventional internal combustion engines.

[0039] Furthermore, in this embodiment, the cross-sectional area (minimum cross-sectional area) CS2 of the return passage 16 is set to be smaller than the cross-sectional area (minimum cross-sectional area) CS1 of the blow-by gas passage 13. This makes it possible to reduce the amount of blow-by gas flowing from the crankcase 12 into the return passage 16. Also, by suppressing the inflow of blow-by gas through the return passage 16, the resistance to blow-by gas inflow is suppressed, and the oil liquefied by gas-liquid separation can be smoothly returned to the crankcase 12 via the return passage 16.

[0040] Furthermore, in this embodiment, the first blow-by gas passage 14 is located outside the center of the cylinder (the third cylinder C3 in this embodiment) at the end of the cylinder block 1 in the cylinder row direction (the rear end in this embodiment). Therefore, it is possible to apply pulsation (pulse pressure) mainly generated in a single cylinder (the third cylinder C3) to the first blow-by gas passage 14. As a result, relatively large pulsations act on the first blow-by gas passage 14, which can promote gas-liquid separation of blow-by gas.

[0041] Furthermore, in this embodiment, the return passage 16 is connected to the crankcase 12 at a position between cylinders in the cylinder row direction (between the second cylinder C2 and the third cylinder C3 in this embodiment). Therefore, the pulsations generated in adjacent cylinders act on the return passage 16, and these cancel each other out, thereby reducing the pulsations acting on the return passage 16. As a result, the oil liquefied by gas-liquid separation can be smoothly returned to the crankcase 12 via the return passage 16.

[0042] Furthermore, in this embodiment, the second blow-by gas passage 15 is connected to the return passage 16 inside the separator 7. Therefore, in addition to the oil separated in the second blow-by gas passage 15, the oil separated inside the separator 7 can also be returned to the crankcase 12 via the return passage 16. This allows for efficient return of the oil from the blow-by gas via the return passage 16.

[0043] Furthermore, the rear end of an internal combustion engine (EG) is relatively cramped, as components such as a transmission or motor reduction gear are often located there.

[0044] In contrast, in this embodiment, the separator 7 is positioned on the side surface of the cylinder block 1, thereby improving the layout flexibility of the separator 7.

[0045] The present invention is not limited to the configurations illustrated in the above embodiments, and can be freely modified according to, for example, the specifications of the internal combustion engine (EG) to which the present invention is applied. [Explanation of symbols]

[0046] 1…Cylinder block 2…Cylinder head 3…Cylinder head cover 4… Oil pan 5…Front cover 6…Intake passage 7... Separator 11... Cylinder 12... Crankcase 13…Blow-by gas passage 14…First blow-by gas passage 15…Second blow-by gas passage 16…Return aisle 23…Bypass passage 81... Fresh air intake piping 82...Blow-by gas recirculation piping CS1... Cross-sectional area of ​​the blow-by gas passage CS2… Cross-sectional area of ​​the return passage CS3…Cross-sectional area of ​​the bypass passage EG... Internal combustion engine

Claims

1. An internal combustion engine comprising: a cylinder block in which multiple cylinders are arranged in parallel; a separator attached to the cylinder block and having a labyrinth structure formed between it and the cylinder block; and a blow-by gas passage provided in the cylinder block and guiding blow-by gas flowing in through a crankcase located at the lower part of the cylinder block to the separator, The aforementioned blow-by gas passage is The upstream first blow-by gas passage opening into the crankcase, A downstream second blow-by gas passage that bends relative to the first blow-by gas passage downstream of the first blow-by gas passage and opens to the separator, Includes, An internal combustion engine in which the second blow-by gas passage is connected to the crankcase via a return passage that branches off at a position closer to the separator than the first blow-by gas passage.

2. An internal combustion engine according to claim 1, An internal combustion engine wherein the minimum cross-sectional area of ​​the return passage is smaller than the minimum cross-sectional area of ​​the blow-by gas passage.

3. An internal combustion engine according to claim 1, An internal combustion engine in which the first blow-by gas passage is connected to the crankcase at a position outside the cylinder center located at the end in the cylinder row direction.

4. An internal combustion engine according to claim 1, An internal combustion engine in which the return passage is connected to the crankcase at a position between cylinders in the cylinder row direction.

5. An internal combustion engine according to claim 1, An internal combustion engine in which the second blow-by gas passage is connected to the return passage inside the separator.

6. An internal combustion engine according to claim 5, The separator is provided on the side surface of the cylinder block, The second blow-by gas passage extends in the direction of the cylinder row in an internal combustion engine.

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