Head cover structure

Abstract

To provide a head cover structure which can avoid a risk of freezing as much as possible by installing an oil separator in a head cover limited in volume to thereby shorten a length of an external pipe for blow-by gas, and which has been rationally improved so as to be capable of providing a sufficient oil capture action while keeping an engine compact.SOLUTION: A head cover structure is configured to introduce blow-by gas into an intake passage C after passing it through the inside of a head cover H. An oil separator A for and capturing and removing oil from the blow-by gas is arranged in the head cover H, and a gas introduction part 7 as an inlet for the blow-by gas in the oil separator A is arranged at an upper end part of the oil separator A. Blow-by gas from a crankcase passes through a circulation space part S sandwiched by an inner surface of the head cover H and an outer surface of the crankcase A and flows to the gas introduction part 7.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a head cover structure applied to various engines equipped with a blow-by gas reflux device, and more particularly to a head cover structure provided with an oil separator.

Background Art

[0002] In diesel engines for industrial use and the like, there are many structures equipped with a so-called blow-by gas reflux device that returns blow-by gas to the intake passage after passing through the inside of the cylinder head cover (hereinafter abbreviated as the head cover).

[0003] In a configuration in which blow-by gas from the crankcase is taken out of the head cover and returned to the intake passage after passing through the inside of the head cover, a blow-by gas passage is often provided above the valve operating mechanism in the head cover. Inside the head cover, since the blow-by gas passage is likely to be a narrow and flat passage in the vertical direction, an oil separator for capturing the oil component from the blow-by gas is generally provided outside the head cover as a dedicated part (for example, Patent Document 1).

[0004] In a structure in which the oil separator is arranged on the side of the cylinder block, there is an advantage that it can have a sufficient capacity because there is not much space limitation like in the head cover. However, since the oil separator, which is a dedicated part, is added as an auxiliary machine of the engine, there are the following disadvantages.

[0005] That is, since dedicated piping means such as hoses are used for the inlet passage and the outlet passage of the blow-by gas to the oil separator, space is required for arranging these piping means (the engine is likely to become large and bulky in the lateral direction). In addition, since the gas passage from the head cover to the intake passage becomes long and the length of the external piping also becomes long, the risk of freezing of the moisture contained in the blow-by gas during cold weather increases.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-35787 [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] An object of the present invention is to provide a head cover structure that is reasonably improved so that an oil separator is provided in a head cover with a limited volume by structural devising, the length of the external piping of blow-by gas is shortened to avoid the risk of freezing as much as possible, and while suppressing the increase in size of the engine, a sufficient oil capturing action can be obtained. [Means for Solving the Problems]

[0008] The present invention relates to a head cover structure, configured to guide blow-by gas through the inside of the head cover and then to the intake passage, an oil separator for capturing and removing oil from the blow-by gas is provided inside the head cover, and a gas introduction part, which is an inlet of the blow-by gas in the oil separator, is provided at the upper end part of the oil separator.

[0009] And it is convenient if the blow-by gas from the crankcase flows to the gas introduction part through the flow space part sandwiched between the inner surface of the head cover and the outer surface of the oil separator. Further, it is more convenient if the flow space part has a space part between the inner surface of the ceiling wall of the head cover and the upper surface of the oil separator and / or a space part between the inner surface of the side wall of the head cover and the side surface of the oil separator.

[0010] For the present invention other than the above, Configuration refer to Claims 1 to 6 those in the claims. [Effects of the Invention]

[0011] According to the present invention, since the oil separator is built into the head cover, external piping can be omitted or its length can be drastically reduced. As a result, these external piping and the oil separator are not exposed to cold air in winter or the like, and the blow-by gas existing around can be expected to have a heat-insulating or heat-preserving effect on the oil separator. Therefore, it is improved so that the inconvenience that moisture freezes and blocks inside the oil separator and the external piping does not occur first.

[0012] Since the gas introduction part of the blow-by gas is at the upper end of the oil separator, the moving distance of the blow-by gas to the gas introduction part in the head cover can be reasonably increased, and the capturing effect of the oil component from the blow-by gas can be enhanced. Then, the blow-by gas flowing downward from the oil separator changes its direction and advances, and the capturing effect of the oil component is promoted by inertial separation due to the change in direction.

[0013] As a result, it is possible to provide a reasonably improved head cover structure that provides a sufficient oil capturing effect while providing an oil separator in the head cover, shortening the length of the external piping of the blow-by gas to avoid the risk of freezing as much as possible, and suppressing the increase in the size of the engine.

[0014] In addition, if the oil filter is provided in the gas introduction part of the oil separator, a cleaning effect can be expected to prevent foreign substances (such as carbon) from accumulating on the oil filter due to the flow of the blow-by gas from top to bottom in the oil separator.

Brief Description of the Drawings

[0015] [Fig. 1] Vertical sectional view of the main part showing the head cover and the outline of its internal structure [Fig. 2] Cross-sectional view of the main part showing the head cover and the outline of its internal structure [Fig. 3] Bottom view of the upper head cover [Fig. 4] Top view of an industrial diesel engine [Fig. 5] Plan view of the oil separator [Fig. 6] Cross-sectional view taken along line Z-Z in Figure 5 [Fig. 7] Cross-sectional view taken along line YY in Figure 6 [Fig. 8] A detailed longitudinal sectional view of a main part showing the internal structure of a head cover. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the head cover structure according to the present invention will be described with reference to the drawings for an industrial diesel engine. For the sake of simplicity, the structure of the oil separator A is somewhat simplified (e.g., the cover lid 18 is omitted) in Figs. 1 and 2. For the sake of simplicity, Fig. 5 shows the structure of the oil separator A in a simplified form (e.g., the cover lid 18 is omitted). Suction hole part 18a is only partially drawn.

[0017] In the industrial diesel engine E shown in plan view in Fig. 4, 28 denotes a turbocharger, 29 denotes a cooling fan, 30 denotes an exhaust treatment device, 31 denotes an alternator, 32 denotes a water flange, 33 denotes a transmission case, 34 denotes an intake manifold, and H denotes a head cover. This engine E is provided with a blow-by gas recirculation device B, which will be described later.

[0018] 1 to 3, the head cover H is composed of a lower head cover 2 which is assembled by bolting onto a cylinder head 1, and an upper head cover 3 which is assembled by bolting onto the lower head cover 2. The head cover H houses an oil separator A which captures and separates oil components in the blow-by gas.

[0019] Blow-by gas from the crankcase enters the oil separator A through the inside of the cylinder head 1, the lower head cover 2, and the upper head cover 3. The blow-by gas from which the oil component has been removed to some extent by the oil separator A is discharged from the gas outlet portion 3G of the upper head cover 3 to the outside of the head cover H, and a blow-by gas reflux device B is provided so as to flow into the intake passage (fresh air introduction passage) C through the reduction passage 27.

[0020] That is, it is configured to guide the blow-by gas g through the inside of the head cover H to the intake passage C, and an oil separator A that captures and removes oil from the blow-by gas g is provided inside the head cover H. The gas introduction portion 7, which is the inlet of the blow-by gas g in the oil separator A, is provided at the upper end portion of the oil separator A. Note that 35 shown in FIGS. 1 and 4 is a wire harness for driving a fuel injection injector (not shown), and 36 shown in FIGS. 1 and 3 is an extraction hole for passing the wire harness 35.

[0021] As shown in FIGS. 1, 2, and FIGS. 5 to 8, the oil separator A has a main body case 4 composed of an upper first case 5 and a lower second case 6, and an element case (filter case) 9A. And a gas introduction portion 7 that is the inlet of the blow-by gas, a gas lead-out portion 8 that is the outlet of the blow-by gas, an oil element (oil filter) 9 that captures the oil component, a check valve 10, a bypass valve 16, etc. are provided.

[0022] As shown in FIGS. 1, 2, 6, and 7, the oil element 9 is rectangular in plan view, long in the front-rear direction and relatively short in the vertical width, and is housed in a dedicated element case 9A and assembled and integrated with a plurality (four places) of bolts 22 on the upper side of the first case 5. The element case 9A is composed of an open-topped box-shaped main body case portion 9a that houses the oil element 9, and a plate-shaped cover lid (an example of a plate-like body) 18 that is bolted at a plurality of places on the main body case portion 9a. The cover lid 18 is formed with a number of suction hole portions 18a, which are, for example, circular holes (also the gas inlet 9g and the gas introduction portion 7), and it is convenient if the blow-by gas g flowing on the ceiling portion in the upper head cover 3 enters the element case 9A from those numerous suction hole portions 18a.

[0023] As shown in FIGS. 6 and 7, a discharge case portion 9b protruding downward is formed below the rear portion of the main body case portion 9a. For example, the discharge case portion 9b having a circular shape in the vertical direction view is fitted in a liquid-tight manner into the introduction opening 5a formed on the upper side of the rear portion of the first case 5 via a seal ring (not shown).

[0024] That is, the blow-by gas that has passed through the oil element 9 (with some oil components removed) and the oil components (engine oil, water, etc.) captured by the oil element 9 are configured to enter the first case 5 from the discharge case portion 9b. Then, the blow-by gas g entering the main body case 4 from the introduction opening 5a flows forward through the internal passage 17 and is discharged from the gas outlet portion 8 formed on the upper side of the front end portion of the first case 5. Note that 8a shown in FIGS. 5 and 6 is a sealing body such as a rubber ring.

[0025] The first case 5 has a front uppermost wall 5A having a gas outlet portion 8, an upper wall 5B on which the element case 9A is disposed, and a rear uppermost wall 5C. Nut portions 25 for bolting the element case 9A are formed at the rear end portion of the front uppermost wall 5A and the rear uppermost wall 5C. The highest walls of the main body case 4 are the front and rear uppermost walls 5A and 5C, but the highest wall of the oil separator A is the cover lid 18.

[0026] In the lower second case 6, a pair of front and rear oil reservoirs 20 and 21 that protrude downward are formed, and at the lower ends of the respective oil reservoirs 20 and 21, oil outlets 20A and 21A with check valves 10 are provided. Each of the oil reservoirs 20 and 21 extends downward in a stepwise narrowing state so as to avoid the components of the moving valve mechanism V. Therefore, each of the oil outlets 20A and 21A has an oil outlet 20A and 21A that is located within the height region of the moving valve mechanism V while avoiding the components of the moving valve mechanism V that are arranged below the internal passage 17.

[0027] The oil components supplemented from the blow-by gas g moving in the internal passage 17 and the oil components flowing down from the element case 9A are configured to return from the oil outlets 20A and 21A of the front and rear oil reservoirs 20 and 21 into the upper head cover 3 (inside the engine). That is, at the lower ends of the respective oil reservoirs 20 and 21, there are oil outlets 20A and 21A that are located within the height region of the moving valve mechanism V while avoiding the components of the moving valve mechanism V that are arranged below the internal passage 17.

[0028] Also, at the rear end of the second case 6 of the element case 9A, a bypass valve 16 that can be opened downward is provided. When the internal pressure of the upper head cover 3 (the internal pressure inside the engine) becomes a predetermined pressure or more, the bypass valve 16 that has been in the "closed" state until then becomes the "open" state, and is configured to release the pressure to the intake passage via the internal passage 17 and the gas outlet portion 8.

[0029] As shown in FIGS. 1, 2, and 3, on the ceiling wall 3E of the upper head cover 3, a rib wall 23 that extends downward from the inner ceiling surface 3e is formed. The rib wall 23 has a horizontal rib 23A that extends rightward from the left inner surface 3c that is the inner surface of the left side wall 3C, and a vertical rib 23B that bends 90 degrees backward from the right end of the horizontal rib 23A and then continues to merge with the rear inner surface 3b that is the inner surface of the rear side wall 3B. Inside the ceiling wall 3E, a thick valve rib 24A having a downward opening 24 is formed following the front side of the horizontal rib 23A.

[0030] The oil separator A is bolted to the upper end of the lower head cover 2 such that the upper part of the element case 9A enters a bottomless box-shaped space surrounded by the ceiling wall 3E, left side wall 3C, rear side wall 3B, horizontal rib 23A, and vertical rib 23B of the upper head cover 3. As a result, the blow-by gas g flowing from the crankcase passes through the narrow flow space portions 11 to 15 (flow space portion S) which are spaces between the front, rear, left, and right side walls 4A to 4D and ceiling wall 4E of the oil separator A and the front, rear, left, and right side walls 3A to 3D and ceiling wall 3E of the upper head cover 3, and a number of Suction hole part flows to 18a.

[0031] As shown in FIGS. 1, 2, and 8, the front flow space portion 11 includes the space between the front side wall 4A of the main body case 4 (front outer surface 4a) and the front side wall 3A of the upper head cover 3 (front inner surface 3a), and the space between the front surface (symbol omitted) of the element case 9A and the rear surface (symbol omitted) of the horizontal rib 23A. The rear flow space portion 12 is the space between the rear side wall 4B of the main body case 4 (rear outer surface 4b) and the rear side wall 3B of the upper head cover 3 (rear inner surface 3b), and also includes the space between the rear surface (symbol omitted) of the element case 9A and the rear inner surface 3b.

[0032] The left flow space portion 13 is the space between the left side wall 4C of the main body case 4 (left outer surface 4c) and the left side wall 3C of the upper head cover 3 (left inner surface 3c), and also includes the space between the left surface (symbol omitted) of the element case 9A and the left inner surface 3c. The right flow space portion 14 is the space between the right side wall 4D of the main body case 4 (right outer surface 4d) and the right side wall 3D of the upper head cover 3 (right inner surface 3d), and also includes the space between the right surface (symbol omitted) of the element case 9A and the vertical rib 23B.

[0033] Also, the upper flow space portion 15, which is the space between the cover lid 18 and the ceiling wall 3E of the upper head cover 3 (and the ceiling inner surface 3e) above the cover lid 18, is also a flow space portion S (see FIGS. 6 and 9). In the case of an oil separator (not shown) having a structure in which the oil element 9 is installed inside the main body case 4, the space between the ceiling wall 4E of the main body case 4 (and the upper surface 4e) and the ceiling wall 3E of the upper head cover 3 (and the ceiling inner surface 3e) becomes the upper flow space portion 15. In the structure shown in FIGS. 6 and 7, the upper surface of the cover lid 18 corresponds to the upper surface 4e of the oil separator A.

[0034] Next, as indicated by the arrows in FIGS. 1 and 2, the blow-by gas g in the head cover H moves upward through the front, rear, left, and right flow space portions 11 to 14 (and may also pass through the upper flow space portion 15), and enters the oil element 9 (into the element case 9A) from the gas introduction portion 7, which is the inlet of the oil separator A, that is, from the suction hole portion 18a of the cover lid 18 (see FIG. 6). When the oil element 9 moves from top to bottom, the oil component in the blow-by gas is captured, and the captured oil component and the blow-by gas g from which the oil component has been removed to a certain extent flow from the discharge case portion 9b into the internal passage 17 of the first case 5.

[0035] When the blow-by gas g flowing downward changes its direction forward to advance in the internal passage 17, an effect (inertial force separation effect) in which the oil component cannot turn and moves downward to be captured is also added, and the captured oil component flows down and is discharged into the head cover H from the two oil accumulation portions 20 and 21 at the front and rear. The blow-by gas g advancing in the internal passage 17 changes its direction upward at the front end portion of the main body case 4 and is discharged from the gas outlet portion 8 to the outside of the oil separator A. When changing the direction from advancing to rising, the separation and capture effect of the oil component from the blow-by gas g due to the inertial force separation effect can also be expected.

[0036] The blow-by gas g exiting from the gas outlet 8 flows through the pressure regulating valve 26 provided on the ceiling wall 3E of the upper head cover 3 and then through a dedicated reduction passage 27 (see Fig. 4) such as a hose pipe and into the intake passage C. As a specific example of the intake passage C, as shown in Fig. 4, it is the air supply portion 28A of the supercharger (turbo) 28, and the end of the reduction passage 27 merges into the air supply portion 28A.

[0037] As described above, the blow-by gas g is configured to be guided to the intake passage C after passing through the inside of the head cover H, and an oil separator A for capturing and removing oil from the blow-by gas g is provided inside the head cover H. The gas introduction portion 7, which is the inlet of the blow-by gas g in the oil separator A, is provided at the upper end portion of the oil separator A.

[0038] That is, the blow-by gas g rising in the head cover H rises through the front, rear, left, and right flow space portions 11 to 14 and the upper flow space portion 15, and then enters the suction hole portion 18a (see Fig. 6), which is the gas introduction portion 7 of the oil separator A. Therefore, compared with a structure in which the gas introduction portion is provided beside or below the oil separator, the movement distance until reaching the oil separator can be reasonably increased without increasing the size of the head cover, and the opportunity to capture the oil component can also be increased. Of course, compared with the case where the oil separator is provided outside the engine, there is also an advantage that the oil separator and the external piping are cooled, and the risk of moisture freezing is reduced or eliminated.

[0039] Since the blow-by gas from the crankcase is configured to flow to the gas introduction portion 7 through the flow space portion S (the front, rear, left, and right flow space portions 11 to 14) sandwiched between the inner surface of the head cover H and the outer surface of the oil separator A, there is an advantage that a sufficient flow of the blow-by gas g (flow rate per unit area) can be obtained while arranging the gas introduction portion 7 in the narrow space portion (the upper flow space portion 15) between the oil separator A and the ceiling wall 3E of the head cover H.

[0040] Since the gas inlet 9G (suction hole portion 18a: see Fig. 6) of the oil element 9 is configured to be the gas introduction portion 7 of the oil separator A, a rationalized structure that enables the sharing of components and compactness is realized compared to the case where they exist separately. Further, since the element case 9A is bolted to the main body case 4 from above, there is also the advantage that the oil element 9 alone can be easily replaced and maintained by removal.

[0041] In the oil separator A, since an internal passage 17 that occupies most of the internal volume is provided below the oil element 9 and the gas outlet portion 8, both of which are arranged at the upper part, there are more locations in the element case 9A where the direction of the blow-by gas g changes (descending → forward, forward → ascending), and there is an advantage that the capture effect of the oil component by inertial separation can be easily obtained.

[0042] Since the gas inlet 9g (gas introduction portion 7) has a large area formed by a large number of suction hole portions 18a formed in the cover lid 18, the blow-by gas g can be efficiently and smoothly introduced into the oil element 9 from the upper flow space portion 15 formed by the ceiling surface 3e and the upper surface of the cover lid 18. There is also an advantage that the blow-by gas g that has traveled a long distance to the uppermost part inside the head cover 2 changes its direction at the gas inlet 9g, and the capture effect of the oil component by inertial separation can be expected.

[0043] Further, since oil outlets 20A and 21A located within the height region of the valve mechanism V are formed at the lower ends of the respective oil storage portions 20 and 21, the space inside the head cover H can be efficiently used to increase the volume of the oil separator A, and there is also an advantage that the captured oil can be returned to the engine while being applied to lubricate the valve mechanism V.

[0044] 〔Alternative Embodiment〕 (1) A head cover structure in which the opening area as the gas introduction portion 7 of the oil separator A is enlarged, such as by omitting the cover lid 18, may be used. Further, the oil element 9 may have an oil separator structured to be housed in the main body case 4.

[0045] (2) As suggested in Fig. 8, an oil separator A having an oil element 9 with a structure in which a non-porous plate-like cover lid 18 and a main body case portion 9a are arranged slightly separated vertically from each other, so that a horizontal introduction slit 19 that opens on the entire circumference in the front, rear, left, and right directions is formed, may be used. In this structure, the blow-by gas g that has flowed to the ceiling portion in the upper head cover 3 enters the element case 9A from the introduction slit 19 that becomes 7. Gas introduction part That is, since the gas introduction portion 7 is configured in the introduction slit 19 that is a circumferential space between the element case 9A and the cover lid 18, the blow-by gas g flows horizontally into the gas inlet 9G (gas introduction portion 7). Therefore, the blow-by gas g that has entered the gas introduction portion 7 changes its path from horizontal to downward, and there is an advantage that the capturing action of the oil component by inertial separation can be expected even at the gas inlet 9G.

[0046] That is, since the gas introduction portion 7 is configured in the introduction slit 19 that is a circumferential space between the element case 9A and the cover lid 18, the blow-by gas g flows horizontally into the gas inlet 9G (gas introduction portion 7). Therefore, the blow-by gas g that has entered the gas introduction portion 7 changes its path from horizontal to downward, and there is an advantage that the capturing action of the oil component by inertial separation can be expected even at the gas inlet 9G. (Summary) In an embodiment of the present invention, as shown in Fig. 3, with the longitudinal direction of the head cover H and the oil separator A being the front-rear direction, and the width direction of the head cover H and the oil separator A intersecting the front-rear direction in a plan view being the left-right lateral direction, a longitudinally long vertical rib 23B is provided closer to the oil separator A than the lateral wall 3D of the head cover H in the front-rear direction. As shown in Fig. 2, the flow space part 12 includes an upper flow space part 15 between the inner surface 3e of the ceiling wall 3E of the head cover H and the upper surface 4e of the oil separator A, and a lateral flow space part 14 having a gap sandwiched between the vertical rib 23B and the oil separator A. The blow-by gas g in the internal passage 17 is configured to float to the upper flow space part 15 through the lateral flow space part 14.

Explanation of Signs

[0047] Inner surfaces of side walls 3a to 3d Inner surface of ceiling wall 3e Sides 4a to 4d Upper surface 4e 7 Gas introduction portion 8 Gas outlet portion 9 Oil filter 9G Gas inlet Spaces 11 to 15 17 Internal passage 18 Plate-like body 20, 21 Oil storage portions 20A, 21A Oil outlets A Oil separator C Intake passage H Head cover S Flow-through space portion V Moving valve mechanism

Claims

1. configured to guide blow-by gas through the inside of the head cover and then into the intake passage, an oil separator for capturing and removing oil from the blow-by gas is provided inside the head cover, a gas introduction part which is an inlet of the blow-by gas in the oil separator is provided at the upper end of the oil separator, the blow-by gas from the crankcase is configured to flow to the gas introduction part through a flow space part sandwiched between the inner surface of the head cover and the outer surface of the oil separator, an oil filter of the oil separator is provided in a state where its gas inlet is the gas introduction part, an internal passage for sending the blow-by gas that has exited the oil filter to a gas outlet part which is an outlet of the blow-by gas in the oil separator is provided under the oil filter, with the longitudinal direction of the head cover and the oil separator being the front-rear direction, and the width direction of the head cover and the oil separator intersecting the front-rear direction in plan view being the left-right lateral direction, longitudinal ribs extending in the front-rear direction are provided between the lateral side walls of the head cover and the oil separator, the flow space part includes an upper flow space part between the inner surface of the ceiling wall of the head cover and the upper surface of the oil separator, and a lateral flow space part having a gap sandwiched between the longitudinal rib and the oil separator, and the head cover structure is configured such that the blow-by gas in the internal passage floats to the upper flow space part through the lateral flow space part.

2. The head cover structure according to claim 1, wherein the flow space part has a space part between the inner surface of the side wall of the head cover and the side surface of the oil separator.

3. The head cover structure according to claim 1, wherein the gas outlet part is provided in an upwardly opening state from the oil separator on the side of the oil filter.

4. The head cover structure according to claim 3, wherein the gas outlet part is arranged so as to be aligned in the cylinder in-line direction with respect to the oil filter.

5. The head cover structure according to any one of claims 1 to 4, wherein a plate-like body covering the upper surface side of the gas introduction part is provided so that blow-by gas flows into the gas introduction part from its lateral side.

6. An oil reservoir portion protruding downward from the oil separator is formed, and a lower end portion of the oil reservoir portion has an oil outlet located within a height region of the moving valve mechanism while avoiding components of the moving valve mechanism disposed below the internal passage. The head cover structure according to any one of claims 1 to 4.

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