JP4396266B2 - Engine cooling system - Google Patents

Description

  The present invention relates to a cooling device used in a water-cooled engine, and more particularly to an engine cooling device in which cooling water discharged from a water pump is directly supplied to a water jacket in a cylinder head.

  The water-cooled engine cooling device supplies the cooling water discharged by the water hump to each water jacket of the cylinder block and cylinder head that constitutes the engine body, and while the temperature of the cooling water after circulating through each part of the water jacket is low Open the short circuit and return the cooling water from the short circuit directly to the suction path of the water pump to promote warm-up, and when the cooling water temperature rises, open the main circuit with the radiator and let the cooling water flow to cool it. And a cooling water circulation system for returning the cooled cooling water to the suction path of the water pump.

  In such a cooling water circulation system, the cooling water circulation system is determined in consideration of the cooling characteristics of the cylinder block and the cylinder head, in addition to the differences in the auxiliary equipment such as the water pump, thermostat, and radiator of the cooling water circulation system. Has been. In other words, it is desirable that the cylinder head be sufficiently cooled because the overlapping wall facing the cylinder block side faces the combustion chamber and the exhaust port and the temperature rises easily. It is necessary to keep the reciprocating piston at an appropriate clearance and to keep the lubricating oil at an appropriate temperature, and to ensure an appropriate temperature.

  Therefore, the basic circulation type engine in which the cooling water after passing through the water jacket in the cylinder block flows into the water jacket in the cylinder head from each opening provided dispersed over the entire upper wall of the cylinder block and returns the cooling water to the water pump. There is a cooling device, and in this case, the flow of cooling water is a smooth flow that generally goes upward from below the engine body, but the cooling efficiency of the cylinder head is relatively low.

  On the contrary, in the engine cooling system of the cylinder head advance cooling system, the water pump cooling water is flowed to the water jacket in the cylinder head, the cooling water after passing through the water jacket is flowed to the water jacket in the cylinder block, and the cooling water is returned to the water pump. Although the cooling efficiency of the cylinder head is relatively high, the temperature of the cooling water flowing into the cylinder block side after passing through the cylinder head varies depending on the operating region, so that the control for keeping the cylinder block side at an appropriate temperature becomes unstable.

Alternatively, in the cooling water branch type engine cooling device that branches the cooling water discharged from the water pump, flows the branching flow to the cylinder block and the cylinder head, and then joins them back to the water pump, the cylinder head and the cylinder block are at the appropriate temperature. Can be kept cool.
A cooling system in which cooling water is divided and supplied to a cylinder head and a cylinder block is disclosed in Japanese Patent Laid-Open No. 2003-172140 (Patent Document 1).

Japanese Patent Application Laid-Open No. 2003-172140.

  By the way, in the cooling water branch type engine cooling device, the cylinder head and the cylinder block can be cooled and held at an appropriate temperature, but in order to do this, the cooling water of the water pump does not pass around the water jacket of the cylinder block, and the longitudinal direction of the cylinder head engine One introduction hole is formed in the vicinity of one end side of this, and cooling water is directly introduced into the introduction hole, and the inflowing cooling water flows toward the cooling water outlet provided on the other end side.

  In such a case, in Patent Document 1, the discharge path of the water pump is divided into two inside the engine main body and is divided into the cylinder head side and the cylinder block side.

  When considering engine compaction, it is preferable that the introduction hole of the cylinder head is provided on one end portion side of the overlapping wall with the cylinder block of the cylinder head and is formed as close to the inside of the cylinder head as possible.

However, the combustion chamber facing wall, the intake / exhaust port, the head bolt boss with the head bolt inserted, the oil flow pipe, etc. are in close proximity and concentrated around the introduction hole on the one end side in the water jacket. Yes, it is difficult to form a cooling water passage.
The present invention has been made on the basis of the above problems, and is to provide an engine cooling device that effectively utilizes a cylinder head bolt boss.

An engine cooling device according to a first aspect of the present invention includes a lower wall of a cylinder head that overlaps with a cylinder block, an annular outer peripheral vertical wall extending from an outer edge of the lower wall, and an inner wall of the outer peripheral vertical wall. The water jacket is surrounded by an intermediate wall integrally joined to the section, and the water jacket has a central flow path for flowing cooling water in the longitudinal direction of the engine along the central area of the combustion chamber facing wall of each cylinder and each cylinder. An engine cooling device comprising both end detours bypassing each lower region of the intake / exhaust port forming wall, wherein the cooling water from the water pump is disposed near the one side end in the engine longitudinal direction of the water jacket. An introduction chamber is formed through an introduction hole formed in the outer circumferential vertical wall, and the introduction chamber has a side facing portion along the engine longitudinal direction of the outer peripheral vertical wall and a one end facing portion in the engine longitudinal direction. A part of the cooling water introduced into the introduction chamber is surrounded by a port forming wall near one end and a head bolt boss into which a head bolt for fixing the cylinder head to the cylinder block is inserted. Branching into a flow toward the end detour on one side as a flow, and further, a flow toward the central flow path after flowing as an inner flow between the head bolt boss and the intake port, and the head bolt boss The flow is divided into a flow toward an end detour on the other side after flowing as an outer flow between one end side facing portion of the outer peripheral vertical wall .

Engine cooling system according to claim 2 of the present invention, in an engine cooling system according to claim 1, wherein the cross-sectional area of the second flow path for flowing the outer flow than the cross-sectional area of the first flow path to flow the inner side flow It is characterized by being set large.

According to the first aspect of the present invention, the head bolt boss is used as a flow dividing member, and the cooling water flow immediately after flowing from the introduction hole is divided into the inner flow and the outer flow from the introduction chamber, and these are divided into the central flow path and the end detour. Pour into. For this reason, the central flow path into which the inner flow flows can surely flow into the central region of the water jacket and flow toward the other end side of the cylinder head. In addition, the cooling water in the end bypass circuit through which the outer flow flows can cool the port forming wall sequentially and flow to the other end side of the cylinder head, and the cooling efficiency of the portion having a relatively large amount of heat generation can be ensured satisfactorily. Furthermore, the flow path shape of the inner flow and the outer flow can be adjusted without providing a separate flow regulating member, and the cooling efficiency can be improved while suppressing an increase in cost.
According to claim 2 of the present invention, the stagnation of the cooling water in the introduction chamber can be prevented by making the cross-sectional area of the second flow path larger than the cross-sectional area of the first flow path.

  FIG. 1 shows an engine cooling apparatus as one embodiment of the present invention. This cooling device is mounted on a four-cycle gasoline engine (hereinafter simply referred to as engine 1) having a four-valve type intake / exhaust system, and the cooling water is circulated along a cooling water circulation system R installed inside and outside the engine. Perform water cooling.

  In the engine 1, the cylinder head 3 and the head cover 4 are sequentially integrally connected to the upper side of the cylinder block 2, and an oil pan 5 that closes the lower side is integrally connected to the lower skirt portion 2 s of the cylinder block 2. A crank chamber is formed in the lower part. The oil pan 5 is provided with a chain case 6 at one end thereof and integrally coupled to each other to form an engine body. As shown in FIGS. 1 and 2, a plurality of cylinders S are provided in the cylinder block 2 and the cylinder head 3, and the intake and exhaust gases sucked into and discharged from the combustion chamber C (see FIG. 4) are controlled. And a crankshaft 7 that rotates in response to output energy received by a piston (not shown) in the combustion chamber C. FIG. 2 shows only the intake port 8 and the exhaust port 9 of the intake / exhaust system.

  The cooling device in such an engine body includes a thermostat 12 and a water pump 13, and a radiator 11 is provided in the vicinity thereof. The radiator 11 is connected and disposed near the other end side (right side in FIG. 1) of the cylinder block 2 using upper and lower pipes 14 and 15, and the thermostat 12 and the water pump 13 are connected to the cylinder block 2 (front side in FIG. 1, front side in FIG. 2). It is attached to the outer walls 16b and 16g on the lower side.

  The cylinder block 2 is provided with a plurality of vertical (vertical Z) cylinders S at predetermined intervals in the longitudinal direction X of the engine, and continuously covers the periphery of the cylinders S with a block-side water jacket 17 and further on the outside. Are continuously covered by the front and rear, left and right vertical outer walls 16 (including 16b), and the upper and lower ends of the four cylinders S and the front, rear, left and right vertical outer walls 16 are connected by the overlapping wall portion 18 and the connecting wall 19. Thus, the block-side water jacket 17 is formed in a closed space.

  An opening m, which will be described later, is formed in the inner part of the outer wall 16 at the upper end of the block-side water jacket 17 so that cooling water from an extending path 37, which will be described later, is introduced. Further, the block-side water jacket 17 is formed with a communication path 54 in the overlapping wall portion 38 that overlaps with the other upper part of the other end side. Formed to flow into

One end side (lower side in FIG. 3) of the cylinder block 2 is formed as an end inner wall 16f, and an extending portion 16g projects from the left and right ends of the end inner wall 16f, and the flange portion of the extending end is a chain case 6 It overlaps with the connecting flange 601 on the side, and is fastened and joined to each other with a bolt (not shown).
The water pump 13 and the thermostat 12 of the cooling water circulation system R are disposed close to each other at a portion where the end inner wall 16f and the rear outer wall 16b of the cylinder block 2 overlap (on the lower right side in FIG. 3).

  As shown in FIG. 3, the thermostat 12 is formed by protruding a cylindrical base portion 21 covering the thermostat 12 from the rear outer wall 16b, and a lid-like joint portion 22 is integrally joined to the annular tip portion to form an outer shell portion. The first and second inflow chambers 23 and 24 and the outflow chamber 25 therebetween are defined in the outer shell. In addition, the first and second inflow chambers 23 and 24 are opened and closed in conjunction with each other, and first and second valve bodies 27 and 28 are integrally coupled to each other with the temperature sensing portion 26 interposed therebetween. The temperature sensing unit 26 can switch and move so as to selectively guide the cooling water in the first and second inflow chambers 23 and 24 to the outflow chamber 25 by sensing the cooling water temperature.

As shown in FIGS. 1 and 3, the first inflow chamber 23 is connected to the branch pipe portion 291 of the outflow pipe 29 of the cylinder head 3 via a short circuit 31. Similarly, the second inflow chamber 24 is connected to the protruding end of the outflow pipe 29 via a cooling path 32 including the upper pipe 14, the radiator 11, and the lower pipe 15.
As shown in FIG. 3, the outflow chamber 25 communicates with a suction passage 34 that passes through a protruding wall portion 33 that projects from one end of the rear outer wall 16 b and communicates with a pump chamber 131 described later.
The protruding wall 33 has a base end side overlapping the rear outer wall 16b and one extending portion 16g and protruding in the cylinder lateral width direction Y. In particular, one end facing surface F facing one end side (downward in FIG. 3) extends left and right. A surface continuous with the portion 16g is formed, and the case joining surface fc of the chain case 6 is formed so as to be able to come into close contact with the one end facing surface F.

The chain case 6 has a connection flange 601 and a front wall 602 that are substantially continuous in the vertical direction, has a concave cross section in plan view, and forms the chain housing chamber 30 when joined to the one end facing surface F. In addition, a thick bulging portion 36 is integrally formed continuously at a portion facing the protruding wall portion 33, and the water pump 13 is disposed at this portion.
The water pump 13 is recessed in the case joint surface fc of the thick bulging portion 36, and a pump chamber 131 communicating with the suction passage 34, an impeller (not shown) accommodated in the chamber 131, and a rotating shaft of the impeller are connected. The pump drive part (not shown) arrange | positioned by the outer wall side of the thick bulging part 36, and the case side discharge path 132 extended from the upper end side of the pump chamber 131 are provided. The water pump 13 receives a driving force from a drive unit (not shown) and circulates and supplies cooling water to the cooling water circulation system R.

The tip of the case side discharge path 132 is formed so as to project and communicate with an extension path 37 formed on the wall 33 side.
As shown in FIGS. 1 and 3, the extension path 37 protrudes and is separated from the block-side water jacket 17 in the wall-shaped portion 371 formed in the base end portion of the wall portion 33 and subsequently in the thick portion of the rear outer wall 16 b. And a vertically oriented portion 372 formed as described above. The upper end of the vertically oriented portion 372 is formed as a communication port 372m that opens to the overlapping wall portion 18 that is the upper wall of the rear outer wall 16b.

In particular, the opening is recessed toward the head-side water jacket 42 side, and this portion overlaps with the overlapping wall portion (low wall) 38 of the cylinder head 3 to form a branch path r, and its end is on the block side It is formed as an opening m facing the water jacket 17.
Thus, the vertical portion 372 that is formed in the thick portion of the rear outer wall 16b and flows the cooling water upwards reaches the head side water jacket 42 through the communication port 372m and the opening m that reaches the block side water jacket 17. And divert cooling water.

  The overlapping wall portion 38 which is the lower wall of the cylinder head 3 is overlapped with the overlapping wall portion 18 (upper wall) of the cylinder block 2 via a gasket (not shown). In the cylinder head 3, an annular outer peripheral vertical wall 39 extending vertically from the outer edge of the overlapping wall portion 38 is continuously formed, and the intermediate wall is irregularly integrally joined to the inner wall portion of the outer peripheral vertical wall 39. 41 (see FIG. 4), and a head-side water jacket 42 is formed between the upper and lower sides of the intermediate wall 41 and the overlapping wall portion 38. In addition, the code | symbol e in FIG. 2 shows the sealing cap of the mold attachment / detachment hole formed in the outer peripheral vertical wall 39 at the time of casting.

The head-side water jacket 42 is formed in a space portion not interfering with a valve system and an ignition system member (not shown). As shown in FIG. 4, the overlapping wall portion 38 of the cylinder head 3 is formed with a combustion chamber facing wall 381 at a portion facing each cylinder S, and the combustion chamber facing wall 381 has a port p1 of an intake / exhaust valve (not shown). A mounting hole p2 for the spark plug 43 is formed.
The head-side water jacket 42 forms a cooling water passage continuous in the engine longitudinal direction X. A concentrated introduction hole 44 (see FIGS. 1 and 2) is formed on one end side of the overlapping wall portion 38, and An outlet boss 521 having an outlet 52 is formed on the outer peripheral vertical wall 39, and the outlet pipe 29 is integrally coupled to the outlet boss 521.
The concentrated introduction hole 44 communicates with the communication port 372 m at the time of polymerization with the polymerization wall portion 18 on the cylinder block 2 side, and introduces cooling water discharged from the water pump 13 through the extension path 37.

  As shown in FIGS. 2 and 5, the cooling water that has passed through the concentrated introduction hole 44 flows into the introduction chamber 44 </ b> A, and the introduction chamber 44 </ b> A has an intermediate wall 41 whose height h (see FIGS. 4 and 5). The periphery is surrounded by the rear facing portion 39b and the one end facing portion 39r of the outer peripheral vertical wall 39, the intake port forming wall 45 of the intake port p1, and the head bolt boss 46 to which a head bolt (not shown) is fitted. It is. The head bolt boss 46 constitutes a flow diverting member, and an inner passage 47 (first flow passage) through which the inner flow s1 flows between the intake port forming walls 45, and an outer flow s2 flows between the head bolt boss 46 and the one end side facing portion 39r. An outer passage 48 (second flow path) is formed. The introduction chamber 44A divides the cooling water into an inner flow s1, an outer flow s2, and an intake port downward flow f3 that flows directly into the lower portion of the intake port forming wall 45.

The inner passage 47 passes a part of the cooling water flow from the introduction chamber 44A to the combustion chamber facing wall 381 (see FIG. 4), which is a portion facing the combustion chamber C of the cylinder S located on one end side (left end side in FIG. 4). An inner flow s1 that flows close to is generated. The outer passage 48 flows from the introduction chamber 44A to another part of the cooling water flow toward the exhaust port forming wall 53 of the exhaust port p1 along the one end side facing portion 39r which is the outer peripheral wall on one end side (left end side in FIG. 2). An outer flow s2 is generated. As described above, the head bolt boss 46 functions as a diversion member in which one side of the peripheral wall and the other side divert the cooling water flow into the inner flow s1 and the outer flow s2.
The head bolt boss 46 forms a passage (inner passage 47, outer passage 48) with a predetermined width by the outer wall, the outer peripheral vertical wall 39 and the intake port forming wall 45, so that the inner flow s1 and the outer flow s2 are rectified. It also functions as a rectifying member.

Here, the inner passage 47 (first flow path) of the inner flow s1 and the outer passage 48 (second flow path) of the outer flow s2 extend the length of the head bolt boss 46 so that the respective flow passage areas can be increased as much as possible. It is formed so as to ensure a relatively large dimension in the direction (vertical direction in FIG. 5), thereby enlarging the flow path area relatively easily and ensuring an increase in flow rate. Further, if the flow passage area of the outer passage 48 is set larger than the flow passage area of the inner passage 47, the stagnation of the cooling water in the introduction chamber 44A can be prevented.
Although the peripheral wall of the head bolt boss 46 is formed as a cylindrical outer peripheral surface, it may be formed as a peripheral wall a having a streamlined curved surface as shown by a two-dot chain line in FIG. The effect is further improved.

  The head-side water jacket 42 has a central flow path F1 in which cooling water flows in the engine longitudinal direction X along a central region that sequentially faces the combustion chamber facing wall 381 of each cylinder in the water jacket 42, and intake and exhaust of each cylinder. End detours F2 and F3 that detour the respective lower regions of the port forming walls 45 and 53 are formed.

The operation of the engine cooling apparatus having such a configuration will be described.
When the water pump drive unit (not shown) drives the water pump 13, the cooling water sucked from the suction passage 34 is branched after passing through the case-side discharge passage 132 and the extension passage 37, and passes through the opening m to the block-side water jacket 17. The cooling water after passing through each water jacket reaches the outflow pipe 29 and is returned to the water pump 13 through the communication port 372m and the concentrated introduction hole 44. In this case, when the cooling water temperature is relatively low, for example, when the thermostat 12 opens the short circuit 31 and closes the cooling path 32, the cooling water from the outflow pipe 29 is not radiated and the water pump 13 is dissipated. Returned to When the temperature of the cooling water is relatively high, the thermostat 12 closes the short circuit 31 and opens the cooling path 32, so that the cooling water from the outflow pipe 29 is radiated by the radiator 11 and then the water pump. Return to 13.

  In such an engine cooling device, a part of the inner flow s1 and the outer flow s2 divided into the head bolt boss 46 in the cooling water flowing into the head side water jacket 42 from the concentrated introduction hole 44 is mainly the central flow path. It flows into F1 and sequentially cools the vicinity of the flaming surface facing portion of the ignition system on the intake / exhaust port forming walls 45 and 53 and the combustion chamber facing wall 381 in the vicinity of each combustion chamber C and heads toward the outflow pipe 29.

  Further, a part of the outer flow s2 divided into the head bolt boss 46 flows toward the end bypass F3, and the exhaust port forming wall 53 in the vicinity of each combustion chamber C is sequentially cooled. Head for. Similarly, the intake port downward flow f3 from the concentrated introduction hole 44 flows into the end bypass F2, and the intake port forming wall 45 in the vicinity of each combustion chamber C is sequentially cooled, and is directed from the outlet 52 to the outlet pipe 29. .

  As described above, the engine cooling device has the concentrated introduction hole 44 formed in the overlapping wall portion 38 of the cylinder head 3 so that the cooling water from the case side discharge passage 132 of the water hump 13 is supplied into the rear facing portion 39b of the cylinder block 2. Then, the water is branched to the block-side water jacket 17, supplied to the concentrated introduction hole 44, and supplied to the head-side water jacket 42. For this reason, the cooling water introduction pipe is not provided in the vicinity of the outside of the engine body, and it is not necessary to secure a space for arranging the external cooling water introduction pipe, and the engine cooling device of the present invention can ensure the ease of mounting.

Further, the head bolt boss 46 serves as a diverting member, and the cooling water flow immediately after flowing from the concentrated introduction hole 44 is diverted from the introduction chamber 44A into the inner flow s1 and the outer flow s2, and these are divided into the central flow path F1 and the end detour F2. , Pour into F3. For this reason, the central flow path F1 into which the inner flow s1 flows can surely flow into the central region of the head-side water jacket 42 and flow to the outlet 52 on the other end side of the cylinder head. In addition, the cooling water in the end detour F3 into which the outer flow s2 flows can cool the exhaust port forming wall 53 sequentially and flow to the outlet 52, so that the cooling efficiency of the portion having a relatively large calorific value can be ensured satisfactorily. .
Furthermore, the flow path shape (for example, the peripheral wall a) of the inner flow s1 and the outer flow s2 can be adjusted without providing a separate flow regulating member, and the cooling efficiency can be improved while suppressing an increase in cost.

In addition, since the cooling water flowing into the central flow path F1 and the end detour F3 is divided into the inner flow s1 and the outer flow s2, the flow passage area of the outer passage 48 through which the outer flow s2 flows can be made relatively small, and the cylinder head The protrusion to the chain accommodation chamber 30 side that is the outside of the one end side facing portion 39r that is the outer peripheral wall of the outer circumference wall can be eliminated or suppressed, and the space utility of the chain accommodation chamber 30 is improved.
In the above, the engine of FIG. 1 provided a 4-valve type intake / exhaust system, but the present invention can be similarly applied to a 2-valve type engine. In this case as well, the engine cooling device of FIG. The effect is obtained.

  In the above description, the engine cooling device of the present invention is applied to a gasoline engine. However, the present invention can be similarly applied to other engines such as diesel engines.

1 is a schematic side view of an engine to which an engine cooling device according to an embodiment of the present invention is applied. FIG. 2 is an enlarged plan sectional view of a cylinder head of the engine of FIG. 1. It is a principal part notched top view of the cylinder block of the engine of FIG. It is an expanded sectional side view of the cylinder head of the engine of FIG. FIG. 2 is an enlarged cutaway cross-sectional view in the vicinity of a head bolt boss in the cylinder head of the engine of FIG. 1. It is a disassembled perspective view of the cylinder block and cylinder head of the engine of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder block 3 Cylinder head 13 Water hump 133 Discharge path 16 Outer wall 16b Rear outer wall 17 Block side water jacket 18 Polymerization wall part 30 Chain accommodating chamber 33 Projecting wall part 372m Connection port 38 Polymerization wall part 37 Extension path 42 Head side water Jacket 44 Concentrated introduction hole (introduction hole)
44A Introduction chamber 46 Head bolt boss 47 Inner passage (first flow path)
48 Outer passage (second flow path)
s1 Inner flow s2 Outer flow R Cooling water circulation system X Engine longitudinal direction Y Engine lateral width direction

Claims (2)

Surrounded by a low wall of the cylinder head that overlaps with the cylinder block, an annular outer peripheral vertical wall extending from the outer edge of the lower wall, and an intermediate wall integrally joined to the inner wall of the outer peripheral vertical wall A water jacket, wherein the water jacket bypasses the central flow path for flowing cooling water in the longitudinal direction of the engine along the central area of the combustion chamber facing wall of each cylinder and the lower areas of the intake / exhaust port forming wall of each cylinder An engine cooling device having an end detour of
An introduction chamber into which cooling water from a water pump is introduced through an introduction hole formed in the low wall is formed near one side end of the water jacket in the longitudinal direction of the engine.
The introduction chamber includes a side facing portion along the engine longitudinal direction of the outer peripheral vertical wall, a one end facing portion in the engine longitudinal direction, a port forming wall near the one end, and a head bolt for fixing the cylinder head to the cylinder block. Is surrounded by the head bolt boss inserted,
A part of the cooling water introduced into the introduction chamber branches into the flow toward the end detour on the one side as the intake port downward flow, and further, the inner flow between the head bolt boss and the intake port. The flow toward the central flow path after flow and the flow between the head bolt boss and the one end side facing portion of the outer peripheral vertical wall as an outer flow and then flow to the other end detour after flow An engine cooling device characterized by. An engine cooling system according to claim 1, the engine cooling system, characterized in that the cross-sectional area of the second flow path for flowing the outer flow is set larger than the sectional area of the first flow path to flow the inner side flow .

Images