Patent Application
20190211780
The following description relates to an internal combustion engine that introduces coolant from inside the cylinder head to an exhaust gas recirculation (EGR) cooler.
Japanese Laid-Open Patent Publication No. 2013-83206 describes an example of internal combustion engines including an EGR cooler. In a typical internal combustion engine including an EGR cooler, coolant circulates in the cylinder block and then flows into the cylinder head. The coolant then circulates in the cylinder head before being introduced into the EGR cooler.
In the cylinder head, the section in the vicinity of a spark plug is located immediately above a combustion chamber. Some of the coolant circulating in the cylinder head flows through the vicinity of the spark plug and is thus more likely to receive heat generated in the combustion chamber than the coolant flowing in a zone set apart from the spark plug. That is, the temperature of the coolant that has flowed through the vicinity of the spark plug tends to be high. If such high-temperature coolant is introduced into the EGR cooler, the cooling efficiency of EGR gas used in the EGR cooler is lowered.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
In accordance with one aspect of the disclosure, an internal combustion engine is provided that includes a cylinder block, a cylinder-block passage provided in the cylinder block, a cylinder head, a cylinder-head passage, cylinders, an introducing portion, a restricting wall, and communicating portions. The cylinder-head passage is provided in the cylinder head and configured such that coolant flows into the cylinder-head passage after circulating in the cylinder-block passage. The cylinders are arranged side-by-side in the cylinder block. A direction in which the cylinders are arranged side-by-side is a cylinder arrangement direction. The introducing portion is provided at an end of the cylinder head in the cylinder arrangement direction and configured to introduce the coolant flowing in the cylinder-head passage into an EGR cooler. One of the cylinders closest to the introducing portion in the cylinder arrangement direction is a predetermined cylinder. The restricting wall is provided between a spark plug provided for the predetermined cylinder and the introducing portion in the cylinder-head passage and is configured to restrict flow of the coolant from a section corresponding to the spark plug toward the introducing portion. Communicating portions arranged at corresponding positions in a flow direction of the coolant in the cylinder-block passage to cause the cylinder-block passage and the cylinder-head passage to communicate with each other. A direction perpendicular to both an extending direction of a central axis of each of the cylinders and the cylinder arrangement direction is a predetermined direction. A certain one or certain ones of the communicating portions are arranged at positions closer to an intake manifold than the restricting wall in the predetermined direction.
In the above-described configuration, coolant flows from the cylinder-block passage into the cylinder-head passage via the certain one(s) of the communicating portions. The restricting wall limits the flow toward the introducing portion of the comparatively high-temperature coolant that has flowed through the vicinity of the spark plug in the cylinder-head passage. This facilitates the flow to the introducing portion of the coolant that has flowed into the cylinder-head passage via the certain one(s) of the communicating portions. The coolant that has flowed into the cylinder-head passage via the certain one(s) of the communicating portions thus does not flow in the vicinity of the spark plug. This limits the temperature rise of the coolant, thus limiting the reduction of the cooling efficiency of EGR gas by the EGR cooler.
In the above-described engine, the restricting wall may be set apart from an intake-port separating wall, which is a separating wall that separates a predetermined intake port and the cylinder-head passage from each other. Specifically, the predetermined intake port refers to one of the intake ports arranged in the cylinder head that is located closest to the introducing portion in the cylinder arrangement direction.
In the above-described configuration, some of the comparatively low-temperature coolant that has flowed from the cylinder-block passage into the cylinder-head passage via the certain one(s) of the communicating portions flows to the vicinity of the spark plug via the clearance between the intake-port separating wall and the restricting wall. This may improve the cooling efficiency of the combustion chamber as compared to a case in which the comparatively low-temperature coolant does not flow to the vicinity of the spark plug.
There may be a great distance from the certain one(s) of the communicating portions to the introducing portion. In this case, the coolant that has flowed into the cylinder-head passage via the certain one(s) of the communicating portions tends to receive a great amount of heat by the time the coolant reaches the introducing portion. That is, the greater the distance from the certain one(s) of the communicating portions to the introducing portion, the higher the temperature of the coolant introduced into the EGR cooler tends to be. Therefore, in the above-described engine, the introducing portion may be formed at a position closer to the intake manifold than the restricting wall in the predetermined direction. In this configuration, the distance from the certain one(s) of the communicating portions to the introducing portion is relatively small. The coolant that has flowed into the cylinder-head passage via the certain one(s) of the communicating portions receives a correspondingly small amount of heat by the time the coolant reaches the introducing portion. This limits the temperature rise of the coolant that is introduced into the EGR cooler.
A section of the cylinder head closer to the introducing portion than the restricting wall in the cylinder arrangement direction is a first end. The engine further includes an EGR passage section and a passage separating wall. The EGR passage section is arranged in the first end section of the cylinder head and configured such that EGR gas flows toward the EGR cooler through the EGR passage section. The passage separating wall is arranged in a section of the cylinder head closer to an exhaust manifold than the introducing portion in the predetermined direction. The passage separating wall is a separating wall that separates the cylinder-head passage and the EGR passage section from each other.
In the above-described configuration, the coolant flowing in the vicinity of the passage separating wall, which separates the cylinder-head passage and the EGR passage section from each other, in the cylinder-head passage cools the EGR gas that flows in the EGR passage section. That is, since the EGR gas flows in the cylinder head, the temperature of the EGR gas is lowered to a certain extent by the time the EGR gas flows into the EGR cooler. As a result, the temperature of the EGR gas that flows out of the EGR cooler becomes further lowered.
If the distance from the certain one(s) of the communicating portions to the passage separating wall is great, the comparatively low-temperature coolant, which has flowed into the cylinder-head passage via the certain one(s) of the communicating portions are less likely to reach the vicinity of the passage separating wall. This hampers a coolant flow in the vicinity of the passage separating wall, thus reducing the cooling efficiency of the EGR gas that flows in the EGR passage section.
Thus, a passage restricting portion is preferably arranged in a section closer to the introducing portion than the restricting wall in the cylinder arrangement direction and between the introducing portion and the passage separating wall in the predetermined direction. The restricting portion is configured to decrease a width of the cylinder-head passage in the extending direction of the central axis of the corresponding cylinder.
In the above-described configuration, the passage restricting portion reduces the cross-sectional flow area of the corresponding section of the cylinder-head passage. The coolant that has flowed into the cylinder-head passage via the aforementioned certain one(s) of the communicating portions passes through this section while flowing toward the passage separating wall. This increases the flow velocity of the coolant and thus allows the coolant that has flowed into the cylinder-head passage via the aforementioned certain one(s) of the communicating portions to readily reach the vicinity of the passage separating wall. This ensures a coolant flow in the vicinity of the passage separating wall, thus limiting the reduction of the cooling efficiency of the EGR gas that flows in the EGR passage section.
For example, the passage restricting portion may be a projection projecting toward the cylinder block from a section of a peripheral wall of the cylinder-head passage located on a side opposite to the cylinder block.
Other features and aspects will be apparent from the following detailed description, the drawings, and the claims.
Throughout the drawings and the detailed description, the same reference numerals refer to the same elements. The drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience.
The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be apparent to one of ordinary skill in the art. The sequences of operations described herein are merely examples, and are not limited to those set forth herein, but may be changed as will be apparent to one of ordinary skill in the art, with the exception of operations necessarily occurring in a certain order. Also, descriptions of functions and constructions that are well known to one of ordinary skill in the art may be omitted for increased clarity and conciseness.
The features described herein may be embodied in different forms, and are not to be construed as being limited to the examples described herein. Rather, the examples described herein have been provided so that this disclosure will be thorough and complete, and will convey the full scope of the disclosure to one of ordinary skill in the art.
Unless indicated otherwise, a statement that a first layer is “on” a second layer is to be interpreted as covering both a case where the first layer directly contacts the second layer and a case where one or more other layers are disposed between the first layer and the second layer or the substrate. Likewise, A statement that a feature is “connected to” another feature is interpreted as covering both a case where the feature is directly connected to the other feature, and a case where the feature is indirectly connected to the other feature.
An internal combustion engine 10 according to embodiments will now be described with reference to
As illustrated in
With reference to
The engine 10 has an EGR device 40. The EGR device 40 recirculates the exhaust gas, as EGR gas, from inside the exhaust manifold 32 into an intake pipe. The term EGR stands for exhaust gas recirculation. The EGR device 40 has an upstream EGR passage 41, an in-cylinder-head EGR passage 42, an EGR cooler 43, and a downstream EGR passage 44. The upstream EGR passage 41 is connected to the exhaust manifold 32. The in-cylinder-head EGR passage 42 is connected to the upstream EGR passage 41 and provided in the cylinder head 20. The EGR cooler 43 is connected to the in-cylinder-head EGR passage 42 and configured to cool the EGR gas. The downstream EGR passage 44 is configured such that the EGR gas flows in the downstream EGR passage 44 after being cooled by the EGR cooler 43. In the present embodiment, the in-cylinder-head EGR passage 42 corresponds to the EGR passage section. The EGR passage section is the section in the cylinder head 20 in which the EGR gas flows.
As shown in
As illustrated in
A restricting wall 24 is provided in the section of the cylinder-head passage 50 between the plug-surrounding passage section 51 and the introducing portion 55. One of the two intake ports 21 for the cylinder 123 that is closer to the introducing portion 55 in the cylinder arrangement direction X is defined as a predetermined intake port 21A. An intake-port separating wall 25 is a separating wall that separates the predetermined intake port 21A and the cylinder-head passage 50 from each other. The restricting wall 24 is set apart from the intake-port separating wall 25. Specifically, the restricting wall 24 is arranged at a position closer to the introducing portion 55 than the intake-port separating wall 25 in the cylinder arrangement direction X. Also, the restricting wall 24 is arranged at a position closer to the exhaust manifold 32 than the intake-port separating wall 25 in the predetermined direction Y (on the upper side, as viewed in
One of the two exhaust ports 22 for the cylinder 123 that is closer to the introducing portion 55 in the cylinder arrangement direction X is defined as a predetermined exhaust port 22A. The restricting wall 24 is also set apart from an exhaust-port separating wall 26. The exhaust-port separating wall 26 is a separating wall that separates the predetermined exhaust port 22A and the cylinder-head passage 50 from each other. Specifically, the restricting wall 24 is arranged at a position closer to the introducing portion 55 than the exhaust-port separating wall 26 in the cylinder arrangement direction X. Also, the restricting wall 24 is arranged at a position closer to the intake manifold 31 than the exhaust-port separating wall 26 in the predetermined direction Y (on the lower side, as viewed in
Specifically, the distance between the restricting wall 24 and the intake-port separating wall 25 is substantially equal to the distance between the restricting wall 24 and the exhaust-port separating wall 26.
The cylinder-head passage 50 has outside-intake-port passage sections 53. The outside-intake-port passage sections 53 are located on the opposite side of the intake ports 21 to the plug-surrounding passage section 51. The outside-intake-port passage sections 53 include an outside-intake-port passage section 53A, which is located in the vicinity of the predetermined intake port 21A, which, in turn, is one of the two intake ports 21 for the cylinder 123. The outside-intake-port passage section 53A is connected to a passage zone 54, which is continuous with the introducing portion 55 in the cylinder-head passage 50.
Specifically, with reference to
As shown in
Specifically, as shown in
An operation and advantages of the present embodiment will now be described.
Coolant flows into the cylinder-head passage 50 via the communicating portions 60B, 60C. The coolant then flows in the cylinder-head passage 50 as represented by the broken arrows in
Coolant also flows into the cylinder-head passage 50 via the communicating portion 60A. The coolant flows in the cylinder-head passage 50 as represented by the solid arrows in
As discussed above, the restricting wall 24 is provided between the plug-surrounding passage section 51 and the introducing portion 55. The restricting wall 24 thus restricts the flow of the coolant from the plug-surrounding passage section 51 toward the introducing portion 55. This limits the introduction, to the introducing portion 55, of the comparatively high-temperature coolant that has received heat from the combustion chamber 14. On the other hand, correspondingly facilitated is the introduction of the coolant that has flowed into the cylinder-head passage 50 via the communicating portions 60B, 60C, that is, the comparatively low-temperature coolant that has received only a limited amount of heat from the combustion chamber 14, to the introducing portion 55. As a result, the reduction of the cooling efficiency of EGR gas used in the EGR cooler 43 may be limited.
A clearance exists between the restricting wall 24 and the intake-port separating wall 25. This causes the comparatively high-temperature coolant in the plug-surrounding passage section 51 to flow toward the introducing portion 55 via the clearance. However, the flow of the comparatively high-temperature coolant is limited by the comparatively low-temperature coolant that has flowed into the cylinder-head passage 50 via the communicating portions 60B, 60C. As a result, as represented by the solid arrows in
Specifically, some of the comparatively low-temperature coolant that has flowed to the clearance between the restricting wall 24 and the intake-port separating wall 25 flows toward the plug-surrounding passage section 51 via the clearance. By causing the comparatively low-temperature coolant to flow into the plug-surrounding passage section 51 in this manner, the cooling efficiency of the combustion chamber 14 using coolant may be improved.
Embodiments may further have the following features.
(1) The introducing portion 55 is arranged at a position closer to the communicating portions 60B, 60C than the restricting wall 24 in the predetermined direction Y. The distance from each communicating portion 60B, 60C to the introducing portion 55 thus becomes comparatively small. This limits increase in the amount of heat received by coolant after the coolant flows into the cylinder-head passage 50 via the communicating portions 60B, 60C until the coolant reaches the introducing portion 55. That is, the temperature rise is limited in the coolant introduced into the EGR cooler 43, thus the cooling efficiency of EGR gas used in the EGR cooler 43 may be improved.
(2) In the first end section 20A of the cylinder head 20, the cylinder-head passage 50 and the in-cylinder-head EGR passage 42 are adjacent to each other with the passage separating wall 27 located between the cylinder-head passage 50 and the in-cylinder-head EGR passage 42. Therefore, the coolant that flows in the vicinity of the passage separating wall 27 in the cylinder-head passage 50 cools the EGR gas that flows in the in-cylinder-head EGR passage 42. This further lowers the temperature of the EGR gas that is recirculated into an intake pipe.
Specifically, the in-cylinder-head EGR passage 42 is arranged at a position closer to the exhaust manifold 32 than the introducing portion 55 in the predetermined direction Y. This hampers the introduction, to the introducing portion 55, of the coolant that has received heat from the EGR gas flowing in the in-cylinder-head EGR passage 42. As a result, a temperature rise is restrained in the coolant that is introduced into the EGR cooler 43 via the introducing portion 55.
(3) The passage restricting portion 28 is arranged between the communicating portions 60B, 60C and the passage separating wall 27 in the predetermined direction Y. The passage restricting portion 28 decreases the cross-sectional flow area of the corresponding section in the cylinder-head passage 50. The coolant that has flowed into the cylinder-head passage 50 via the communicating portions 60B, 60C passes through this section while flowing toward the passage separating wall 27. This increases the flow velocity of the coolant. In this manner, the coolant that has flowed into the cylinder-head passage 50 via the communicating portions 60B, 60C readily reaches the vicinity of the passage separating wall 27. This ensures a coolant flow in the vicinity of the passage separating wall 27, thus limiting the reduction of the cooling efficiency of the EGR gas that flows in the in-cylinder-head EGR passage 42.
The above-described embodiments may be modified as follows. The above-described embodiments and the following modifications can be combined as long as the combined modifications remain technically consistent with each other.
The passage restricting portion 28 may be configured by a projection that is provided in a section of the peripheral wall 50a of the cylinder-head passage 50 opposed to the cylinder block 11 and projects toward the opposite side to the cylinder block 11.
Alternatively, the passage restricting portion 28 may be configured by two projections. One of the projections is provided in a section of the peripheral wall 50a of the cylinder-head passage 50 opposed to the cylinder block 11 and projects toward the opposite side to the cylinder block 11. The other one of the projections is provided in a section of the peripheral wall 50a of the cylinder-head passage 50 that is located on the opposite side to the cylinder block 11 and projects toward the cylinder block 11.
The passage restricting portion 28 may be omitted if the coolant that has flowed into the cylinder-head passage 50 via the communicating portions 60B, 60C is allowed to flow to the vicinity of the passage separating wall 27 without increasing the flow velocity of the coolant by way of the passage restricting portion 28.
The flow path of the EGR gas may be configured such that the EGR gas flows from the exhaust manifold 32 to the EGR cooler 43 without passing through the interior of the cylinder head 20.
If the introducing portion 55 is located on the opposite side of the restricting wall 24 to the spark plug 33 in the cylinder arrangement direction X, the introducing portion 55 does not necessarily have to be arranged at a position closer to the intake manifold 31 than the restricting wall 24 in the predetermined direction Y. The introducing portion 55 may be arranged at, for example, the position corresponding to the restricting wall 24 in the predetermined direction Y.
In the illustrated embodiments, the distance between the restricting wall 24 and the intake-port separating wall 25 is substantially equal to the distance between the restricting wall 24 and the exhaust-port separating wall 26. However, embodiments are not restricted to this. The distance between the restricting wall 24 and the intake-port separating wall 25 may be unequal to the distance between the restricting wall 24 and the exhaust-port separating wall 26. For example, the distance between the restricting wall 24 and the intake-port separating wall 25 may be greater than the distance between the restricting wall 24 and the exhaust-port separating wall 26.
Alternatively, the distance between the restricting wall 24 and the intake-port separating wall 25 may be smaller than the distance between the restricting wall 24 and the exhaust-port separating wall 26. Such a small distance between the restricting wall 24 and the intake-port separating wall 25 may enhance the effect of limiting the flow of comparatively high-temperature coolant from the plug-surrounding passage section 51 to the introducing portion 55.
If the restricting wall 24 is set apart from the intake-port separating wall 25, a section of the restricting wall 24 may be located at a position corresponding to the intake-port separating wall 25 in the cylinder arrangement direction X.
The restricting wall 24 may be adjacent to the intake-port separating wall 25.
While this disclosure includes specific examples, it will be apparent to one of ordinary skill in the art that various changes in form and details may be made in these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be considered in a descriptive sense only, and not for purposes of limitation. Descriptions of features or aspects in each example are to be considered as being applicable to similar features or aspects in other examples. Suitable results may be achieved if the described techniques are performed in a different order, and/or if components in a described system, architecture, device, or circuit are combined in a different manner, and/or replaced or supplemented by other components or their equivalents. Therefore, the scope of the disclosure is defined not by the detailed description, but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents are to be construed as being included in the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-002044 | Jan 2018 | JP | national |
