JP6079594B2 - Multi-cylinder engine cooling structure - Google Patents

Description

  The present invention relates to a cooling structure for a multi-cylinder engine in which a jacket spacer is disposed on a water jacket formed in a cylinder block of the multi-cylinder engine, and more particularly to a technique for uniformly cooling a plurality of cylinder bores.

  Conventionally, as a cooling structure of a multi-cylinder engine, there is a structure in which a water jacket through which a coolant flows is formed around a cylinder bore of a cylinder block, and a jacket spacer is disposed on the water jacket. An example of such a cooling structure is disclosed in Patent Document 1.

  In this cooling structure, a water jacket is formed around four cylinder bores of a cylinder block constituting an in-line four-cylinder engine, a jacket spacer is disposed on the water jacket, and a cylinder block that forms an outer periphery of the water jacket A cooling water introduction portion is formed at one end of the outer peripheral wall in the cylinder row direction. The jacket spacer includes a crank-side water passage forming portion that covers a substantially lower half portion of the cylinder bore and forms a crank-side water passage on the outside, and a combustion chamber-side water passage formation portion that forms a combustion chamber-side water passage on the inside. A partition is formed at the boundary of the water channel forming part. Moreover, the opening part is formed in the location corresponding to several cylinder bores of a crank side water channel formation part. Then, the cooling water introduced from the cooling water introduction part flows through the crank side water channel, flows into these openings, and is distributed to the crank side water channel and the combustion chamber side water channel. Further, the cooling water flowing into each opening comes into contact between the cylinder bores corresponding to the opening. Thereby, the space between the cylinder bores is cooled.

JP 2006207459 A

  In the cooling structure of Patent Document 1, the cooling water introduced into the water jacket from the cooling water introduction part flows through the water jacket along the jacket spacer and sequentially flows into the opening far from the opening near the cooling water introduction part. However, the cooling water may not be evenly distributed to the openings.

  That is, the cooling water flowing into the opening on one side in the cylinder row direction is close to the cooling water introduction portion, and therefore has a strong momentum in the flow. Therefore, a large amount of cooling water may flow into the opening. On the other hand, the cooling water flowing into the opening on the other side in the cylinder row direction is away from the cooling water introduction portion and circulates in the circumferential direction of the water jacket, so there is no momentum in the flow. Therefore, the cooling water flowing into the opening is less than the cooling water flowing into the opening close to the cooling water introduction part, and the distance between the cylinder bores far from the cooling water introduction part is more than between the cylinder bores close to the cooling water introduction part. It becomes difficult to be cooled. As a result, there is a problem that the cooling between the plurality of cylinder bores becomes uneven.

  The present invention has been made in view of such points, and an object thereof is to uniformly cool a plurality of cylinder bores.

  In order to achieve the above-mentioned object, the present invention has devised the shape of the jacket spacer to increase the amount of cooling liquid in the opening formed in the circumferential direction of the water jacket from the cooling liquid introduction part. It is made to flow in.

  Specifically, the present invention relates to a cylinder in which a jacket spacer is disposed in a water jacket formed around a plurality of cylinder bores of a water jacket of a cylinder block constituting an in-line multi-cylinder engine, and forms an outer periphery of the water jacket. The following solution was taken for the cooling structure of a multi-cylinder engine in which the coolant from the coolant introduction portion formed on the outer peripheral wall of the block is circulated through the water jacket.

That is, the first invention, the jacket spacer, the disposed in the lower portion of the water jacket of the cylinder block has a spacer main body part which surrounds the lower the entire circumference of the plurality of cylinder bores, the coolant introduction part The coolant is introduced toward the outer peripheral surface of the spacer main body, and the coolant is introduced from the outer peripheral surface of the spacer main body to the inner peripheral surface at the portion corresponding to the cylinder bore at the upper end of the spacer main body. While the opening to be introduced is formed, the cooling that is introduced from the cooling liquid introduction part and flows on the outer circumference of the spacer main body part at least at a position far from the cooling liquid introduction part on the outer peripheral surface of the spacer main body part A guide protrusion is provided for guiding the liquid to an opening formed at a position far from the cooling liquid introduction part in the opening.

According to the first invention, when the coolant is introduced from the coolant introduction part to the water jacket of the cylinder block, the coolant circulates around the water jacket of the cylinder block along the outer periphery of the spacer main body part. Then, at least a guide protrusion provided at a position far from the coolant introduction part on the outer peripheral surface of the spacer main body guides the coolant to an opening formed at a position far from the coolant introduction part. Therefore, the coolant flows into the opening formed in the circumferential direction of the water jacket from the coolant introduction portion and is relatively far from the coolant introduction portion, and the cooling between the cylinder bores corresponding to this opening portion. Sex can be secured. Accordingly, the plurality of cylinder bores can be cooled substantially uniformly.

In a second aspect based on the first aspect, the jacket spacer has a flange that projects outward from the upper end of the spacer body and divides the water jacket of the cylinder block in the vertical direction. Is formed with a holding piece that extends upward and has a tip that is close to the ceiling surface of the water jacket of the cylinder block, and the holding piece guides the coolant flowing above the flange between the cylinder bores. It is characterized by that.

  According to 2nd invention, the front-end | tip of the holding piece part extended upwards from a collar part is adjoining to the ceiling surface of a water jacket. Therefore, even if the jacket spacer floats due to the buoyancy of the cooling liquid, the holding piece comes into contact with the ceiling surface of the water jacket, so that the jacket spacer is held at a predetermined position. Therefore, the spacer main body can stop at the lower part of the water jacket of the cylinder block and always surround the entire lower periphery of the plurality of cylinder bores.

  The holding piece portion flows through the opening formed in the upper end portion of the spacer main body portion to the upper portion of the flange portion, and guides the coolant flowing above the flange portion between the cylinder bores. The cooling property of the upper end part between cylinder bores can be improved.

  As described above, according to the second invention, the cooling performance between the cylinder bores can be enhanced by using the holding piece portion that holds the jacket spacer in a predetermined position.

According to a third invention, in the first or second invention, a first communication path that connects the water jacket of the cylinder block and the water jacket of the cylinder head is formed above each of the openings. The liquid introduction portion is formed at one end portion of the cylinder block outer peripheral wall in the cylinder row direction, and projects outward from the upper end portion of the spacer main body portion so as to divide the water jacket of the cylinder block vertically. A notch is formed at one end, and a second communication path is formed above the notch to communicate the water jacket of the cylinder block and the water jacket of the cylinder head, and the first communication path and The second communication path is formed in a gasket disposed on the lower surface of the cylinder head .

  According to the third invention, the coolant introduced from the coolant introduction portion into the water jacket of the cylinder block first hits the outer peripheral surface of the spacer body portion of the jacket spacer, and reaches the two hands on the one side and the other side in the cylinder row direction. Divided.

Here, the water jacket of the cylinder head is usually set at a lower pressure than the water jacket of the cylinder block. Therefore, the coolant flowing through the water jacket of the cylinder block is pulled by the water jacket of the low-pressure cylinder head. Therefore, of the two divided coolants, the coolant that has flowed to one side in the cylinder row direction flows into the water jacket of the cylinder head through the second communication passage of the gasket from the notch.

On the other hand, the coolant that has flowed to the other side in the cylinder row direction flows on the outer periphery of the spacer main body, makes a substantially round turn around the water jacket of the cylinder block, passes through the second communication passage of the gasket from the notch, and then reaches the water jacket of the cylinder head Flow into. In the course of this circulation, a part of the coolant flows into the opening formed in the upper end portion of the spacer body, and flows into the water jacket of the cylinder head through the first communication path of the gasket . At this time, the coolant comes into contact with the upper end portions between the relatively high temperature cylinder bores, particularly between the cylinder bores that are particularly hot, and cools between the cylinder bores.

  Thus, according to the third aspect of the invention, the space between the cylinder bores can be effectively cooled while circulating the coolant around the cylinder bores.

  As mentioned above, according to this invention, between several cylinder bores can be cooled uniformly.

It is a schematic diagram which shows schematic structure of an engine cooling device. It is a top view which shows the cylinder block of an engine. FIG. 3 is a cross-sectional view corresponding to a cross section taken along the line III-III of FIG. 2 of the engine main body in which a jacket spacer is disposed on the water jacket of the cylinder block. FIG. 4 is a cross-sectional view corresponding to a cross section taken along line IV-IV in FIG. 2 of the engine main body in which a jacket spacer is disposed on the water jacket of the cylinder block. It is the whole perspective view which looked at the jacket spacer from the exhaust side. It is the whole perspective view which looked at the jacket spacer from the intake side. It is a figure which shows a jacket spacer, (a) is a top view, (b) is a side view seen from the exhaust side, (c) is a side view seen from the intake side, (d) is a front view, (e) FIG. It is sectional drawing which shows schematic structure of the cylinder head of an engine. It is a figure which shows the lower surface of the cylinder head to which the gasket was attached. It is a block diagram which shows the structure of an engine control unit. It is a schematic diagram which shows the flow of a cooling water when a flow control valve has opened the 1st cooling water channel | path and closed the 2nd-4th cooling water channel | path. It is a schematic diagram which shows the flow of a cooling water when a flow control valve has opened the 1st-3rd cooling water channel | path and closed the 4th cooling water channel | path. It is a schematic diagram which shows the flow of the cooling water when the flow regulating valve opens the first to fourth cooling water passages. It is the whole perspective view which looked at the jacket spacer concerning other embodiments from the inhalation side.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its application, or its use.

  FIG. 1 schematically shows a configuration of a cooling device 1 in a multi-cylinder engine provided with a cooling structure for a multi-cylinder engine according to an embodiment of the present invention. The engine cooling apparatus 1 heats the interior of the vehicle with water jackets 23 and 24 formed respectively on the cylinder block 21 and the cylinder head 22 constituting the main body 20 of the engine 2 and cooling water (coolant) (air in the vehicle). The heater core 30 of the air conditioning unit disposed inside the dashboard (not shown), etc., the oil cooler 31 for exchanging heat with oil and the transmission fluid (not shown) An ATF warmer 32 for cooling, an EGR cooler 33 disposed in the EGR passage for cooling the exhaust flowing through the EGR passage (not shown) by cooling water, and an EGR for adjusting the exhaust gas flow flowing through the EGR passage Cold EGR valve 34 disposed in the passage and cooling water by outside air First cooling water for circulating cooling water between a radiator 37 disposed at the front of the vehicle for cooling, and a heater core 30 and an exhaust side jacket 24b of the water jacket 24 of the cylinder head 22 which will be described later. Between the passage 40, the second cooling water passage 41 for circulating the cooling water between the oil cooler 31 and the engine main body 20, and between the EGR cooler 33, the EGR valve 34 and the ATF warmer 32 and the engine main body 20. In the third cooling water passage 42 for circulating the cooling water, the fourth cooling water passage 43 for circulating the cooling water between the radiator 37 and the engine body 20, and the water jacket 23 of the cylinder block 21. And a mechanical water pump (hereinafter simply referred to as a water pump) 51 for supplying cooling water.

  The engine 2 is an in-line four-cylinder engine in which four siamese-type cylinders 25, 25,... Arranged in series are arranged in series along the axial direction of a crankshaft (not shown). This is a spark ignition type engine that performs a spark ignition combustion operation (SI operation) at the time of combustion instability or high load in the CI operation of the engine. The engine 2 is composed of the cylinder block 21 made of an aluminum alloy and the cylinder head 22 made of the same aluminum alloy that is assembled to the upper side of the cylinder block 21, and is formed by the cylinder block 21 and the cylinder head 22. In the cylinders 25, 25,..., Pistons (not shown) are configured to move up and down.

  FIG. 2 is a plan view of the cylinder block 21. The engine 2 is mounted horizontally in an engine room provided at the front of the vehicle so that the crankshaft extends in the vehicle width direction. An intake manifold (not shown) for introducing intake air into each cylinder 25 is disposed on the left side (upper side in FIG. 2) of the engine 2, while on the right side (lower side in FIG. 2) of the engine 2. Is provided with an exhaust system (exhaust manifold, etc., not shown). In the cylinder block 21, a cylinder head 22 and a bolt are arranged on the intake side and the exhaust side of both ends of the longitudinal direction (cylinder row direction, hereinafter also referred to as the engine longitudinal direction) and cylinder bores 25 a, 25 a,. Bolt holes 21a, 21a,... Are formed in which bolts for fastening are screwed.

  The water jacket 23 of the cylinder block 21 is formed over the entire engine longitudinal direction of the cylinder block 21 so as to surround the outer periphery of the four cylinders 25, 25,..., And the portions corresponding to the cylinder bores 25a, 25a,. Yes. A cooling water introduction passage 28 (cooling) for introducing cooling water supplied from the water pump 51 into the water jacket 23 is provided at the exhaust-side engine front end of the cylinder block outer peripheral wall 27 forming the outer periphery of the water jacket 23. A liquid introduction part) is formed. The cooling water introduction path 28 is formed at a location corresponding to the lower portion of the water jacket 23 of the cylinder block outer peripheral wall 27 and is inclined toward the rear side of the engine as it approaches the cylinder 25 on the front side of the engine. Therefore, the cooling water introduced into the lower portion of the water jacket 23 from the cooling water introduction path 28 branches to the engine front side and the rear side, most of which flows to the engine rear side, and the other flows to the engine front side.

  The water jacket 23 of the cylinder block 21 is provided with a jacket spacer 80 that forms a water channel for the cooling water flowing through the water jacket 23. 3 and 4 are a cross-sectional view corresponding to a cross section taken along line III-III and a cross-sectional view taken along line IV-IV in FIG. 5 and 6 are overall perspective views of the jacket spacer 80, as viewed from the exhaust side and the intake side, respectively. 7 is a view showing the jacket spacer 80, where (a) is a plan view, (b) is a side view seen from the exhaust side, (c) is a side view seen from the intake side, and (d) is a side view. The side view seen from the engine front side, (e) is a side view seen from the engine rear side. 7B and 7D, the part corresponding to the cooling water introduction path 28 is indicated by a broken line.

  The jacket spacer 80 is made of a heat resistant synthetic resin. The jacket spacer 80 has a spacer main body 81 disposed in the lower portion of the water jacket 23 (substantially lower half portion in the present embodiment). The spacer main body 81 has a substantially cylindrical shape elongated in the longitudinal direction of the engine, and the portions corresponding to the cylinder bores 25a, 25a,... Are constricted along the shape of the cylinder bores 25a, 25a,. As shown in FIGS. 3 and 4, the spacer body 81 is close to the cylinders 25, 25,..., And a slight gap is formed between these cylinders 25, 25,. Further, the exhaust side portion of the spacer body 81 is formed higher than the intake side portion.

  A pair of flange portions 82 and 83 projecting outward are formed at the upper end and the lower end of the spacer body 81. Of the pair of upper and lower flange portions 82 and 83, a lower flange portion (hereinafter referred to as a lower flange portion) 83 is formed over the entire lower end of the spacer main body 81, as shown in FIGS. Has been. As shown in FIGS. 3 and 4, the lower flange 83 has substantially the same width as the lower end width of the water jacket 23.

  Further, on the outer peripheral surface of the spacer main body 81, the upper portion of the lower flange 83 and the lower portion corresponding to the cooling water introduction path 28 are cooled as shown in FIG. 5 and FIG. A guide piece 84 is formed to prevent the cooling water introduced from the water introduction path 28 from flowing down below the spacer body 81 and to guide the introduced cooling water in the longitudinal direction of the engine.

  On the other hand, an upper flange portion (hereinafter referred to as an upper flange portion) 82 (a flange portion) is formed over substantially the entire circumference of the upper end of the spacer main body portion 81, and the upper front flange portion 82 has an engine front end portion. A notch 85 (see FIG. 5) is formed. Specifically, the upper flange 82 is formed from a position corresponding to the cooling water introduction path 28 at the upper end of the spacer main body 81 to the clockwise direction in FIG. A notch 85 is formed from the front end of the engine clockwise to a position corresponding to the coolant introduction path 28 in a clockwise direction.

  Further, as shown in FIGS. 3 and 4, the upper flange portion 82 has the same width as the width at the substantially central portion in the vertical direction of the water jacket 23. Accordingly, the water jacket 23 is partitioned vertically by the upper flange 82. A lower cooling water passage 23 a through which the cooling water introduced from the cooling water introduction passage 28 flows is formed between the upper flange 82 and the lower flange 83.

  Furthermore, as shown in FIG. 5 to FIG. 7, rectangular openings 81 a, 81 a,... That are elongated in the vertical direction are provided at corresponding positions between the cylinder bores 25 a, 25 a,. Is formed. Specifically, openings 81a, 81a, 81a are formed at locations corresponding to 25a, 25a, 25a between the cylinder bores at the upper end of the exhaust body side of the spacer body 81, respectively, while 25a between the cylinder bores at the upper end of the intake side. , 25a, and 25a, openings 81a, 81a, and 81a are formed respectively. 5, only the intake-side openings 81a, 81a, 81a are shown among all the openings 81a, 81a,..., And the exhaust-side openings 81a, 81a, 81a are first holding piece portions to be described later. It is hidden in the exhaust side portion of 88a. 6 shows only the exhaust side openings 81a, 81a, 81a out of all the openings 81a, 81a,..., And the intake side openings 81a, 81a, 81a are the first holding pieces. It is hidden in the intake side portion of 88a.

  As shown in FIGS. 5 and 7 (b), a projecting piece 86 extending substantially horizontally in the longitudinal direction of the engine is outwardly provided at the engine front end of the exhaust side portion of the outer peripheral surface of the spacer body 81. It is formed to overhang. Specifically, the projecting piece 86 is an opening on the uppermost side of the engine from the rear side of the engine corresponding to the coolant introduction path 28 on the upper side of the guide piece 84 and on the lower side of the openings 81a, 81a, 81a on the exhaust side. It extends to the lower part of the part 81a. The protruding width of the protruding piece 86 is set to be slightly smaller than the width at the substantially central portion in the vertical direction of the water jacket 23 as shown in FIG. The protruding width of the protruding piece 86 is preferably the same as the width of the water jacket 23 and has no gap.

  Further, as shown in FIGS. 6 and 7C, the intake side portion on the outer peripheral surface of the spacer main body 81, that is, the portion on the outer peripheral surface of the spacer main body 81 opposite to the formation side of the cooling water introduction path 28. A guide projection 87 is formed so as to project outward from the rear end portion of the engine at the center front side in the longitudinal direction of the engine. Specifically, the guide protrusion 87 is inclined upward toward the front side from the portion corresponding to the cylinder bore 25b on the rear side of the engine in the intake side portion of the lower flange 83 to the lower side of the opening portion 81a on the rear side. It extends substantially horizontally forward to the bottom of the opening 81a on the front side of the engine. The width of the guide protrusion 87 is set to be slightly smaller than the width of the water jacket 23 as shown in FIGS. 3 and 4 in consideration of thermal expansion and the like. The width should be the same as the width of the water jacket 23 and no gap.

  On the other hand, a holding piece 88 that holds the jacket spacer 80 in the water jacket 23 is formed at the upper end of the spacer body 81. As shown in FIGS. 3 and 4, the holding piece 88 extends upward from the upper end of the jacket body 81, and the tip is close to the ceiling surface of the water jacket 23, that is, the lower surface of the gasket 29 described later. . Therefore, even if the jacket spacer 80 floats due to the buoyancy of the cooling water, the holding piece 88 abuts against the lower surface of the gasket 29, so that the jacket spacer 80 is held at a predetermined position. Therefore, the spacer main body 81 stops at the lower part of the water jacket 23 and can always surround the entire lower periphery of the cylinder bores 25b, 25b,.

  The holding piece 88 is formed from the portion corresponding to the upper part of the protruding piece 86 at the outer peripheral end of the upper flange 82 to the clockwise direction in FIG. 7A to the engine front end on the intake side. A holding piece 88a and a second holding piece formed from the position corresponding to the front side of the engine above the protruding piece 86 at the upper end of the spacer body 81 to the front end of the engine in the counterclockwise direction of FIG. 88b and a connecting piece 88c that connects the rear end of the second holding piece 88b and the front end of the first holding piece 88a. An upper cooling water passage 23b through which cooling water flows in a space between the holding piece 88 and the cylinders 25, 25,.

  FIG. 8 is a cross-sectional view showing a schematic configuration of the cylinder head 22 of the engine 2. More specifically, FIG. 8 shows a cross section obtained by cutting the cylinder head 22 along a plane orthogonal to the longitudinal direction of the engine and passing through the center of the cylinder bore 25b. FIG. The cylinder head 22 is made of a block material having a substantially rectangular parallelepiped shape, and the portion corresponding to each cylinder bore 25 b on the lower surface thereof constitutes the ceiling surface of the combustion chamber 26. A pair of intake ports 22a, 22a are formed in the front-rear direction of the engine on the intake side of each ceiling surface, and a pair of exhaust ports 22b, 22b are spaced in the front-rear direction of the engine on the exhaust side. Is formed.

  The water jacket 24 is formed inside the cylinder head 22. The water jacket 24 includes a jacket body 24 a formed around the combustion chamber 26 of each cylinder 25, and an exhaust side jacket 24 b formed on the side of the anti-combustion chamber 26 of the exhaust port 22 b of each cylinder 25. ing.

  The jacket body 24a is formed over the entire engine longitudinal direction of the cylinder head 21 so as to wrap around the outer periphery of the intake / exhaust ports 22a, 22b and plug holes of each cylinder 25 in the vicinity of the periphery of the combustion chamber 26 of each cylinder 25. It communicates with a lead-out path 44 that opens at the rear end. Further, the jacket main body 24a communicates with both ends of the exhaust side jacket 24b in the engine front-rear direction through holes formed at both ends of the engine front-rear direction. Thereby, the cooling water flowing through the jacket main body 24a sequentially flows to the exhaust side jacket 24b.

  The exhaust side jacket 24b is formed over the entire longitudinal direction of the cylinder head 22 in the vicinity of the upper side of the exhaust port 22b of each cylinder 25. An end and a rear end of the exhaust side jacket 24b opposite to the intake side (outside in the short direction) are formed to be thicker than other portions.

  FIG. 9 is a view showing the lower surface of the cylinder head 22 to which the gasket 29 is attached. A gasket 29 is disposed on the lower surface of the cylinder head 22 so as to cover the jacket body 24a. In the gasket 29, circular holes are formed in portions corresponding to the combustion chambers 26, 26,..., While bolt insertion holes are formed in portions corresponding to the bolt holes 21a, 21a,. 29a, 29a,... Are formed.

  Further, circular portions of the gasket 29 corresponding to the cylinder bores 25a, 25a,... Communicate with the water jacket 23 of the cylinder block 21 and the jacket body 24a of the cylinder head 22 through circular first communication passages 29b, 29b,. On the other hand, a portion of the water jacket 23 of the cylinder block 21 corresponding to the front end in the front-rear direction of the engine is formed through a pair of substantially rectangular second communication passages 29c that communicate the water jacket 23 and the jacket body 24a. 29c is formed through.

  When supplied from the water pump 51 to the engine body 20 having the above-described configuration, the cooling water circulates around the water jacket 23 of the cylinder block 21 from the cooling water introduction passage 28 and passes through the second communication passage 29 c of the gasket 29. It flows into the jacket main body 24a of the cylinder head 22 via. During this circulation, the cooling water flows into the jacket body 24a of the cylinder head 22 via the first communication passages 29b, 29b,.

  Here, the flow of the cooling water when circling the water jacket 23 of the cylinder block 21 will be described in detail. First, the cooling water introduced from the cooling water introduction path 28 is a spacer facing the cooling water introduction path 28. It hits the outer peripheral surface of the main body 81 and branches to the engine front side and the rear side. Since the cooling water introduction path 28 is inclined toward the engine rear side as approaching the cylinder 25 as described above, the flow of the cooling water introduced from the cooling water introduction path 28 is directed toward the engine rear side. . Therefore, most of the cooling water introduced from the cooling water introduction path 28 to the exhaust side portion of the water jacket 23 flows toward the rear side of the engine, and the other flows toward the front side.

  The coolant flowing toward the front side of the engine wraps around the cylinder bore 25b on the front side of the engine, passes through the second communication holes 29c and 29c from the cutout portion 85 formed in the upper flange portion 82 of the jacket spacer 80, and the cylinder head 22. Flows into the jacket body 24a.

  On the other hand, the cooling water flowing toward the rear side of the engine is prevented from flowing into the upper cooling water passage 23b by the upper flange 82, the holding piece 88 and the connecting piece 88c in the vicinity of the cooling water introduction passage 28. Therefore, most of this cooling water flows through the lower cooling water passage 23a. The cooling water flowing through the lower cooling water passage 23a is distributed and adjusted up and down by the projecting piece 86 on the engine rear side of the cooling water introduction passage 28, and further, the projecting piece 86 extends in the longitudinal direction of the engine. The rectifying effect is enhanced so that it flows smoothly in the direction.

  When the cooling water flowing through the lower cooling water passage 23a reaches the position of the opening 81a on the front side of the engine, the cooling water flowing above the protruding piece 86 flows into the opening 81a, and the inside of the spacer main body 81 And is pulled upward toward the low-pressure jacket body 24 a of the cylinder head 22. At this time, the cooling water comes into contact with the upper end of the cylinder bore 25a adjacent to the combustion chamber 26, which is located higher than the opening 81a. Therefore, it is possible to effectively cool the upper end portion between the cylinder bores 25a, which tends to be relatively hot.

  On the other hand, the cooling water flowing under the projecting piece 86 is restricted from flowing into the opening 81a by the projecting piece 86, and flows directly toward the rear side of the engine. As a result, it is possible to suppress the flow of cooling water having a high flow rate and high flow pressure flowing in the vicinity of the opening 81a closest to the cooling water introduction path 28, and the cooling water flowing downstream thereof. The flow rate can be increased. As a result, the flow rate of the cooling water flowing into all the openings 81a, 81a,. Therefore, the cylinder bores 25a, 25a,... Can be cooled substantially uniformly.

  The cooling water that has passed through the position of the opening 81a closest to the cooling water introduction path 28 flows through the exhaust side portion of the water jacket 23 toward the engine rear side. On the way, a part of the cooling water flows into the exhaust-side center and the engine rear-side openings 81a and 81a and comes into contact with the corresponding cylinder bores 25a and 25a to cool the cylinder bores 25a and 25a. . And the cooling water which contacted between cylinder bores 25a and 25a flows in into the jacket main body 24a of the cylinder head 22 through the 1st communicating path 29b and 29b of the upper direction.

  The coolant that has flowed through the exhaust side portion of the water jacket 23 circulates around the cylinder bore 25b on the most rear side of the engine, and flows through the intake side portion of the water jacket 23 toward the front side of the engine. At this time, although the distance from the cooling water introduction path 28 is increased and the momentum of the cooling water is reduced, the guide protrusion 87 is formed on the intake side of the outer peripheral surface of the spacer main body 81. Flowing on the upper side of 87, the channel cross-sectional area gradually decreases, and the flow velocity gradually increases. As a result, the cooling water flowing on the intake side of the water jacket 23 flows vigorously into the intake-side openings 81a, 81a, 81a, similarly to the cooling water flowing into the exhaust-side openings 81a, 81a, 81a.

  The cooling water that has flowed into contact with the upper ends of the cylinder bores 25a, 25a, and 25a, particularly the cylinder bores 25a, 25a, and 25a corresponding to the intake-side openings 81a, 81a, and 81a, is cooled and formed above them. It flows into the jacket body 24a of the cylinder head 22 through the first communication passages 29b, 29b, 29b. Therefore, the intake side cylinder bores 25a, 25a, 25a are also cooled to the same extent as the exhaust side cylinder bores 25a, 25a, 25a. Therefore, all the cylinder bores 25a, 25a, 25a can be cooled more uniformly.

  Further, since the guide protrusion 87 extends in the longitudinal direction of the engine, the rectifying action of flowing cooling water in the longitudinal direction of the engine is exhibited in the same manner as the protruding piece 86. The cooling water flowing under the guide projection 87 is stagnant under the guide projection 87.

Then, the coolant flowing through the intake side portion of the water jacket 23 wraps around the cylinder bore 25b on the most front side of the engine and passes through the second communication passages 29c and 29c of the gasket 29 from the notch 85 formed in the upper flange 82. Into the jacket body 24a of the cylinder head 22.

The cooling water which has flowed into the openings 81a of the jacket spacer 80 has a first communication passage 29b of the gasket 29, 29b, ... in addition to flowing into the jacket body 24a of the cylinder head 22 by, while stagnation upper cooling water passage 23b Also flows slowly. At this time, the portions of the holding piece 88 corresponding to the cylinder bores 25a, 25a,... Are constricted along the cylinder bores 25a, 25a,. The cylinder bores 25a are guided by the corresponding portions between the cylinder bores 25a. Therefore, the cooling water flowing through the upper cooling water passage 23b is also used for cooling the cylinder bores 25a, 25a,.

  By the way, the cooling water flowing through the water jacket 23 of the cylinder block 21 may be convected by the flow formed by the water pump 51 or the heat transfer from the combustion chamber 26. Due to this convection, the cooling water in the water jacket 23 of the cylinder block 21 flows into the water jacket 24 of the cylinder head 22 and flows in the water jacket 24, so that the surroundings of the combustion chamber 26 may be cooled. The jacket spacer 80 suppresses such convection due to the cooling water.

  That is, the upper flange portion 82 of the jacket spacer 80 prevents the cooling water flowing through the lower lower cooling water passage 23 a from flowing into the upper cooling water passage 23 b near the combustion chamber 26. Further, the lower flange 83 suppresses the cooling water flowing through the lower cooling water passage 23 a from flowing downward to the spacer main body 81. Accordingly, the cooling water is prevented from flowing into the inside of the spacer body 81, that is, between the spacer body 81 and the cylinders 25, 25,. Therefore, the convection of the cooling water in the water jacket 23 of the cylinder block 21 is suppressed.

  Further, as described above, the cooling water flows while flowing in the upper cooling water passage 23b, and since it is close to the combustion chamber 26, the cooling water may be heated and convection may occur. Here, the heat transfer coefficient due to the natural convection of the liquid in the sealed space is proportional to approximately −1 / 9th power of the ratio of the height to the width of the sealed space (here, the water jacket 23). In other words, the smaller the width, the smaller the width of the heat transfer coefficient, which suppresses natural convection. Therefore, the width of the upper cooling water passage 23b is narrower than that of the water jacket 23 by the holding piece portion 88 that forms the outer periphery of the upper cooling water passage 23b, and the upper cooling water passage 23b is compared with the case where the holding piece portion 88 is not provided. The generated convection is suppressed.

  As described above, the jacket spacer 80 constitutes convection suppressing means that suppresses the cooling water from flowing into the jacket body 24a from the water jacket 23 by the operation of the water pump 51 and flowing into the jacket body 24a. doing.

  The cooling water introduced from the cooling water introduction path 28 flows through the water jacket 23 of the cylinder block 21 as described above, flows into the water jacket 24 of the cylinder head 22, and flows into the outlet path 44.

  As shown in FIG. 1, a first water temperature sensor 70 for detecting the temperature of the cooling water is disposed in the outlet path 44. The lead-out path 44 communicates with the second to fourth cooling water passages 41 to 43.

  A flow control valve 60 that switches a passage through which the cooling water from the lead-out path 44 flows is provided at a communication portion between the lead-out path 44 and the first to fourth cooling water passages 40 to 43. The flow control valve 60 is configured by, for example, a conventionally known flow rate adjustment valve or thermostat, and the internal flow paths thereof are the flow path forming the first cooling water passage 40 and the second to fourth cooling water passages 41 to 43. It is independent of the flow path that constitutes. The operation of the flow control valve 60 is controlled by a flow control valve control unit 7a of an engine control unit (hereinafter referred to as ECU, see FIG. 10) 7.

  As described above, the relatively high-temperature cooling water that has flowed through the water jacket 24 of the cylinder head 22 flows out from the outlet passage 44 to the first to fourth cooling water passages 40 to 43.

  The upstream end portion of the first cooling water passage 40 communicates with the exhaust side jacket 24 b via the flow control valve 60 and the outlet passage 44, while the downstream end portion thereof communicates with the suction side of the water pump 51. In the first cooling water passage 40, a heater core 30 and a second water temperature sensor 71 for detecting the temperature of the cooling water are provided in order from the upstream side. The cooling water flowing through the first cooling water passage 40 exchanges heat with air in the vehicle in the heater core 30 to heat the air, and then flows into the water pump 51.

  The second cooling water passage 41 joins the fourth cooling water passage 43 on the downstream side of the radiator 37. The downstream end of the second cooling water passage 41 communicates with the suction side of the water pump 51. An oil cooler 31 is provided on the upstream side of the joining portion of the second cooling water passage 41 with the fourth cooling water passage 43. The relatively high-temperature cooling water flowing through the second cooling water passage 41 is returned to the suction side of the water pump 51 after exchanging heat with oil in the oil cooler 31.

  The third cooling water passage 42 joins the fourth cooling water passage 43 on the downstream side of the radiator 37 and on the upstream side of the joining portion of the second and fourth cooling water passages 41 and 43. The upstream end of the third cooling water passage 42 communicates with the upstream side of the oil cooler 31 in the second cooling water passage 41, that is, between the flow control valve 60 and the oil cooler 31 in the second cooling water passage 41. . The downstream end of the third cooling water passage 42 communicates with the suction side of the water pump 51. An EGR cooler 33, an EGR valve 34, and an ATF warmer 32 are provided in this order from the upstream side of the third cooling water passage 42 at the upstream side of the junction with the fourth cooling water passage 43. The EGR cooler 33 and the EGR valve 34 are provided in parallel in the third cooling water passage 42. The relatively high-temperature coolant flowing through the third coolant passage 42 exchanges heat with the exhaust gas in the EGR cooler 33 to cool the exhaust gas and exchange heat with the EGR valve 34 in the EGR valve 34, and then in the ATF warmer 32. Heat exchange with the ATF is returned to the suction side of the water pump 51.

  The downstream end of the fourth cooling water passage 43 communicates with the suction side of the water pump 51. A radiator 37 is provided in the fourth cooling water passage 43. The relatively high-temperature cooling water flowing through the fourth cooling water passage 43 is cooled by exchanging heat with the outside air in the radiator 37 and then returned to the suction side of the water pump 51.

  The water pump 51 is, for example, a conventionally known centrifugal pump that sends cooling water by the rotation of the impeller, and the shaft of the impeller is driven by the rotation of the crankshaft of the engine body 20.

  As is well known, the ECU 7 includes a CPU, a memory, an I / O interface circuit, a driver circuit and the like, and performs fuel injection control and ignition timing control for each cylinder 25 for operation control of the engine 2. In addition, the operation of the flow control valve 60 is controlled according to the wall temperature of the combustion chamber 26, the heating operation state, and the like.

  That is, as shown in FIG. 10, the ECU 7 inputs at least a signal from a load state sensor 72 (for example, an accelerator opening sensor or an airflow sensor of a vehicle) for detecting the load state of the engine 2. Thus, the load state of the engine 2 is determined, and the compression self-ignition operation of the engine 2 is performed at a low load, while the spark ignition operation of the engine 2 is performed at a high load. Since the convection of the coolant generated in the water jacket 23 of the cylinder block 21 is suppressed by the jacket spacer 80, the wall temperature of the combustion chamber 26 becomes difficult to be cooled, and the early rise in the wall temperature of the combustion chamber 26 is promoted, and early. Compressed self-ignition combustion can be stabilized and maintained. As a result, the compression self-ignition combustion operation region can be expanded, and fuel consumption can be improved.

  The ECU 7 also includes at least a signal from the first water temperature sensor 70 and a heating operation state sensor 73 (for example, a sensor that detects an on / off state of the heating switch) for detecting the state of the heating operation. A signal is input to determine the wall temperature of the combustion chamber 26 and the state of the heating operation, and the operation of the flow control valve 60 is controlled accordingly.

  The overall flow of the cooling water in the engine cooling apparatus 1 configured as described above is schematically shown in FIG. The figure shows the flow when the flow regulating valve 60 closes the first to fourth cooling water passages 40 to 43. At this time, the flow of cooling water hardly occurs in the water jackets 23 and 24 in the engine body 20. And although the convection of cooling water may arise in the water jacket 23 of the cylinder block 21 by combustion in the combustion chamber 26, the convection of the cooling water in the water jacket 23 is suppressed by the jacket spacer 80 as mentioned above. For this reason, the inflow of cooling water from the water jacket 23 of the cylinder block 21 to the jacket main body 24a of the cylinder head 22 is suppressed, and the cooling water hardly flows in the jacket main body 24a. As a result, the periphery of the combustion chamber 26 is hardly cooled.

On the other hand, when the flow regulating valve 60 closes the second to fourth cooling water passages 41 to 43 and opens the first cooling water passage 40, it is formed from the water pump 51 to the cylinder block 21 as shown in FIG. The cooling water sent to the cooled cooling water introduction path 28 passes from the water jacket 23 of the cylinder block 21 to the jacket main body 24a of the cylinder head 22 through the second communication passage 29c of the gasket 29 without passing through the first communication hole 29b. Passes through the front end of the engine and flows into the exhaust side jacket 24b as it is. Therefore, the cooling water flows into the exhaust-side jacket 24b with almost no flow through the water jacket 23 of the cylinder block 21 and the jacket body 24a of the cylinder head 21. In addition, there is a possibility that the cooling water in the water jacket 23 of the cylinder block 21 is convected by being pulled (induced) by the flow of the cooling water, but this cooling water is provided by the jacket spacer 80 disposed in the water jacket 23. Convection is suppressed. Thereafter, the cooling water flows through the exhaust side jacket 24 b, passes through the outlet passage 44, flows through the first cooling water passage 40, and is returned to the suction side of the water pump 51. At this time, the cooling water exchanges heat with the heater core 30.

When the flow control valve 60 opens the second and third cooling water passages 41 and 42 and closes the fourth cooling water passage 43, the cooling formed from the water pump 51 to the cylinder block 21 as shown in FIG. The cooling water sent to the water introduction path 28 flows from the water jacket 23 of the cylinder block 21 through the first communication path 29b and the second communication path 29c of the gasket 29 to the jacket main body 24a of the cylinder head 22. Also at this time, the convection of the cooling water in the water jacket 23 of the cylinder block 21 is suppressed by the jacket spacer 80. Thereafter, the cooling water flows from the jacket body 24 a through the exhaust side jacket 24 b, then passes through the outlet passage 44, flows through the second and third cooling water passages 41, 42, and is returned to the suction side of the water pump 51. At this time, the cooling water flows between the oil cooler 31, the EGR cooler 33, the EGR valve 34, and the ATF warmer 32, while the cooling water does not flow between the radiator 37. Further, when the flow control valve 60 opens the first cooling water passage 40, the cooling water exchanges heat with the heater core 30 as described above.

  Further, when the flow regulating valve 60 opens the second to fourth cooling water passages 41 to 43, it is sent from the water pump 51 to the cooling water introduction passage 28 formed in the cylinder block 21, as shown in FIG. The cooling water flows into the water jacket 24 of the cylinder head 22 in the same manner as described above, flows through the second to fourth cooling water passages 41 to 43, and then returns to the suction side of the water pump 51. At this time, the cooling water flows between the oil cooler 31, the EGR cooler 33, the EGR valve 34, the ATF warmer 32, and the radiator 37. Further, when the flow control valve 60 opens the first cooling water passage 40, the cooling water exchanges heat with the heater core 30 as described above.

  As described above, the flow control valve 60 opens in the order of the second and third cooling water passages 41 and 42 and the fourth cooling water passage 43 in accordance with the temperature rise of the cooling water.

-Flow control operation control-
Next, the operation control of the engine 2 and the flow control valve 60 by the ECU 7 after the engine is started will be described.

  When the engine is cold (when the engine is warming up) and the cooling water temperature is lower than the first target water temperature (for example, 80 ° C.) and the heating operation is stopped (when there is no heating request), spark ignition of the engine 2 occurs. While operating, the flow control valve 60 is operated so as to close the first to fourth cooling water passages 40 to 43. Thus, the circulation of the cooling water in the water jackets 23 and 24 in the engine main body 20, in particular, the convection of the cooling water in the water jacket 23 of the cylinder block 21 is suppressed by the jacket spacer 80, and the wall temperature of the combustion chamber 26 is cooled. It becomes difficult to be done. As a result, an early rise in the wall temperature of the combustion chamber 26 is promoted.

  On the other hand, when the engine is cold and the cooling water temperature is lower than the first target water temperature and the heating operation is performed (when there is a heating request), the spark ignition operation of the engine 2 is performed as shown in FIG. The flow control valve 60 is operated so as to open the first cooling water passage 40 and close the second to fourth cooling water passages 41 to 43. As a result, the cooling water flows through the water jackets 23 and 24 of the cylinder block 21 and the cylinder head 22. At this time, cooling water is uniformly supplied to the cylinder bores 25a, 25a,... By the jacket spacer 80, and the cylinder bores 25a, 25a,. Furthermore, the convection of the cooling water in the water jacket 23 of the cylinder block 21 is suppressed by the jacket spacer 80, and the flow of the cooling water in the jacket body 24a of the cylinder head 22 is suppressed. As a result, an early rise in the wall temperature of the combustion chamber 26 is promoted. And cooling water distribute | circulates between the heater cores 30, and the inside of a vehicle is heated.

During the heating operation, the flow regulating valve 6 is operated so as to limit the flow rate of the coolant as the rotational speed of the engine 2 increases. Then, when the engine speed increases during the heating operation, the amount of heat held per unit flow rate of the cooling water flowing through the first cooling water passage 40 increases, and part of the heat is not exchanged, and the first cooling is performed. wasteful work in war Tapo amplifier driving force becomes the only circulating the water passage 40 is generated. Therefore, even if the flow rate of the cooling water flowing through the first cooling water passage 40 is reduced, the amount of heat that satisfies the heating requirement can be supplied to the heater core 30. As a result, heater performance can be ensured. Therefore, even if the flow rate of the cooling water flowing through the first cooling water passage 40 is limited as the rotational speed of the engine 2 increases during the heating operation, the heater performance can be ensured. Therefore, a water pump that circulates the cooling water while ensuring the heater performance by restricting the flow rate of the cooling water flowing through the first cooling water passage 40 by the flow regulating valve 60 as the rotational speed of the engine 2 increases during the heating operation. The amount of work 51 is reduced, and the driving load of the engine 2 that drives the water pump 51 can be reduced.

  Further, when the engine is cold and the cooling water temperature becomes equal to or higher than the first target water temperature, the wall temperature of the combustion chamber 26 is assumed to be equal to or higher than the target wall temperature (predetermined temperature), as shown in FIG. The operation state of the engine 2 is switched from the spark ignition operation to the compression self-ignition operation, and the flow control valve 60 is operated so as to open the second and third cooling water passages 41 and 42 and close the fourth cooling water passage 43. Let If it carries out like this, cooling water will distribute | circulate in the water jackets 23 and 24 in the engine main-body part 20. FIG. Further, cooling water flows between the EGR cooler 33, the EGR valve 34, and the ATF warmer 32, heat is exchanged with the exhaust gas in the EGR cooler 33 to cool the exhaust gas, and heat exchange with the EGR valve 34 is performed in the EGR valve 34. Later, the ATF warmer 32 exchanges heat with the ATF. In addition, during the heating operation, the cooling water flows between the heater core 30 and the interior of the vehicle is heated.

  Further, after the completion of warming up of the engine 2 and when the cooling water temperature becomes equal to or higher than the second target water temperature higher than the first target temperature, it is assumed that there is a heat release request from the engine 2 as shown in FIG. The flow control valve 60 is operated so as to open the second to fourth cooling water passages 41 to 43. If it carries out like this, a cooling water will distribute | circulate in the water jackets 23 and 24 in the engine main-body part 20 similarly to the above-mentioned. Further, the cooling water flows between the EGR cooler 33, the EGR valve 34, and the ATF warmer 32 in the same manner as described above. In addition, the cooling water flows between the radiator 37 and the radiator 37 is cooled by exchanging heat with the outside air. In addition, during the heating operation, the cooling water flows between the heater core 30 as described above.

Even after the warm-up of the engine 2 is completed, the cooling water of the water jacket 23 of the cylinder block 21 passes through the openings 81a, 81a,... Of the jacket spacer 80 and contacts the cylinder bores 25a, 25a,. It flows into the jacket body 24a of the cylinder head 22 through the one communication hole 29b, 29b,. Therefore, the cylinder bores 25, 25,... Can be cooled even after the warm-up is completed.
(Other embodiments)
In the above embodiment, the holding piece portion 88 of the jacket spacer 80 is formed over substantially the entire circumference of the upper flange portion 82, but is not limited to this, for example, like a jacket spacer 180 shown in FIG. .. May be formed only at the corresponding portions between the cylinder bores 25a, 25a,. Specifically, the holding piece portions 188, 188,... Are formed at a location corresponding to the upstream side of the cylinder bore 25 a in the upper flange portion 182 so as to be curved along the outer peripheral end of the upper flange portion 182. Yes. When the coolant flowing through the upper coolant passage 23b approaches the cylinder bores 25a, 25a,..., The coolant is guided to the cylinder bores 25a, 25a,. Then, the guided cooling water comes into contact with the cylinder bores 25a, 25a,... And flows into the jacket body 24a of the cylinder head 22 through the upper first communication passages 29b, 29b,.

  Further, in the above embodiment, the guide protrusion 87 is formed only on the intake side portion of the outer peripheral surface of the spacer main body 81, but is not limited to this, for example, cooling water that flows on the outer periphery of the spacer main body 81. It may also be formed on the engine rear side portion of the outer peripheral surface of the spacer main body 81 where the flowing direction changes greatly.

  As described above, the cooling structure for a multi-cylinder engine according to the present invention can be applied to an application for uniformly cooling a plurality of cylinder bores.

2 engine (multi-cylinder engine)
25 Cylinder 25 b Cylinder bore 21 Cylinder head 22 Cylinder block 23 Cylinder block water jacket 24 Cylinder head water jacket 27 Cylinder block outer peripheral wall 28 Coolant introduction path (coolant introduction part)
29b 1st communicating path 29c 2nd communicating path 80 Jacket spacer 81 Spacer main-body part 81a Opening part 82 Upper collar part (saddle part)
85 Notch 87 Guide protrusion 88 Holding piece

Claims (3)

Coolant formed on the outer peripheral wall of the cylinder block, which is provided with a jacket spacer on the water jacket formed around the plurality of cylinder bores of the water jacket of the cylinder block constituting the in-line multi-cylinder engine, and forms the outer periphery of the water jacket A cooling structure for a multi-cylinder engine that circulates coolant from an introduction portion to the water jacket,
The jacket spacer is disposed in the lower portion of the water jacket of the cylinder block has a spacer main body part which surrounds the lower the entire circumference of the plurality of cylinder bores,
The coolant introduction part introduces the coolant toward the outer peripheral surface side of the spacer body part,
While an opening for introducing the coolant from the outer peripheral surface side to the inner peripheral surface side of the spacer main body portion is formed in the corresponding portion between the cylinder bores at the upper end portion of the spacer main body portion ,
The coolant introduced from the coolant introduction part and flowing around the outer periphery of the spacer body part at least at a position far from the coolant introduction part on the outer peripheral surface of the spacer body part is transferred to the coolant liquid in the opening part. A cooling structure for a multi-cylinder engine, characterized in that a guide protrusion is provided for guiding to an opening formed at a position far from the introduction portion. The multi-cylinder engine cooling structure according to claim 1,
The jacket spacer has a flange that projects outward from the upper end of the spacer main body and divides the water jacket of the cylinder block up and down.
The hook part is formed with a holding piece that extends upward and has a tip close to the ceiling surface of the water jacket of the cylinder block.
The cooling structure for a multi-cylinder engine, wherein the holding piece part guides the coolant flowing on the upper side of the flange part between the cylinder bores. The cooling structure for a multi-cylinder engine according to claim 1 or 2,
Above each of the openings, a first communication path is formed to communicate the water jacket of the cylinder block and the water jacket of the cylinder head.
The coolant introduction part is formed at one end of the cylinder block outer peripheral wall in the cylinder row direction,
A notch is formed at one end in the cylinder row direction of the flange that projects outward from the upper end of the spacer body and divides the water jacket of the cylinder block in the vertical direction. A second communication passage is formed to communicate the water jacket of the cylinder block and the water jacket of the cylinder head ;
The cooling structure for a multi-cylinder engine, wherein the first communication path and the second communication path are formed in a gasket disposed on a lower surface of the cylinder head .

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