JP7601534B2 - Monoblock engine - Google Patents

Description

This invention relates to a monoblock engine in which the cylinder head and cylinder block are integrated into the main body block, and is particularly characterized by the manner in which the cooling water flows.

In reciprocating engines such as gasoline and diesel engines, a cooling water jacket is formed around the cylinder to cool the cylinder and piston, and a cooling water jacket is also formed inside the cylinder head.

There are several different cooling methods for engines, but in the case of a typical engine in which the cylinder block and cylinder head are manufactured as separate components, a communication hole is drilled in the gasket between the cylinder head and the cylinder block, and water is often passed from the cylinder block's cooling water jacket to the cylinder head's cooling water jacket through this communication hole and a communication hole (water leg) formed in the cylinder head.

On the other hand, as a cooling method for a monoblock engine, Patent Document 1 discloses that when a block-side cooling water jacket is provided on the cylinder block and a head-side cooling water jacket is provided on the cylinder head 2, multiple communication holes are formed in the cylinder head in a circumferential line to allow cooling water to be sprayed from the block-side cooling water jacket to the head-side cooling water jacket.

Microfilm of Utility Model Publication No. 63-171644

Patent Document 1 can be said to apply the water passage structure of the separated block system directly to a monoblock, but because the cooling water flows into the head side cooling water jacket while circling the block side cooling water jacket, there are problems with increased flow resistance and overcooling of the cylinders. In addition, when casting the main body block, the communication holes are made of sand cores, but the cores become thin bridge-like at the communication holes, increasing the risk of breakage or damage, which may increase the manufacturing effort and reduce the yield.

The present invention was made against this background, and aims to disclose technology for a monoblock engine that can accurately cool the cylinder block and cylinder head without causing manufacturing problems.

The monoblock engine of the present invention is
"A cylinder block integrated with a cylinder head is formed with a group of cylinder bores opening downward and a block-side cooling water jacket surrounding the group of cylinder bores,
The cylinder head is formed with a head-side cooling water jacket that is in direct communication with the block-side cooling water jacket.
This is the basic configuration.

In the above basic configuration,
"A cooling water inlet that is long in the cylinder row direction is provided at the upper end of the block-side cooling water jacket near one end of the cylinder row, or at the lower end of the head-side cooling water jacket near one end of the cylinder row, straddling the first and second cylinders as seen from one end of the cylinder row,
Furthermore, a first notch that is located on the center line of the cylinder row and opens downward, and a second notch that is located circumferentially away from the first notch and opens downward are formed on one end side and the other end side of the cylinder row of the block-side cooling water jacket.
It has the following characteristics:

The present invention can be developed in various ways. For example, in claim 2,
" A third notch that opens upward and is symmetrical to the first notch is formed on each of the ends of the cylinder row of the head-side cooling water jacket. "
The structure is as follows.

The present invention also includes a state in which the cooling water inlet straddles both the upper end of the block-side cooling water jacket and the lower end of the head-side cooling water jacket. In addition , in the present invention, the cooling water inlet can be disposed on either the intake side or the exhaust side, but is preferably disposed on the intake side.

In the present invention, the cooling water inlet is provided at the upper end of the block side cooling water jacket or the lower end of the head side cooling water jacket, so that the cylinders can be prevented from being overcooled. Also, since the cooling water inlet is long in the cylinder row direction, even if the cooling water inlet is provided at the upper end of the block side cooling water jacket or the lower end of the head side cooling water jacket, the cooling water can be reliably sent to the upper part of the block side cooling water jacket, and the upper part of the cylinder can be reliably cooled. Therefore, the knocking prevention function is excellent.

In addition, because the cooling water inlet is located near one end of the cylinder row, the cooling water tends to flow vertically through the block-side cooling water jacket and the head-side cooling water jacket from one end of the cylinder row to the other, which makes the flow of cooling water smoother.

It is theoretically possible to place the cooling water inlet at one end of the cylinder row, but due to relationships with other components and restrictions on water passage formation, the cooling water inlet must often be located on the side of the intake or exhaust side. In this invention, the cooling water inlet is located near one end of the cylinder row for this reason. However, by placing the cooling water near one end of the cylinder row in this way, it is possible to prevent too much cooling water from flowing in the direction of one end of the block side cooling water jacket and to allow the cooling water to flow evenly through the block side cooling water jacket and the head side cooling water jacket.

The block-side cooling water jacket and the head-side cooling water jacket are not connected by a connecting hole but directly, so there is no need to form a bridge-like portion during casting. Also, the cooling water inlet is long in the direction of the cylinder row, so the core can be easily manufactured, and since the notches open downward, the core for forming the notches is also easy to manufacture. Therefore, while the present invention can optimize the flow of cooling water as described above, it can also easily manufacture (cast) a monoblock-type main body block with high precision and without any particular difficulty.

If notches are formed in the block-side cooling water jacket on both ends of the cylinder row, the flow circulating around the block-side cooling water jacket is interrupted, preventing excessive flow of cooling water into the block-side cooling water jacket and preventing over-cooling of the cylinders. The flow of cooling water can also be optimized by adjusting the number and depth of the notches.
In addition, since the second cutout is also formed, the cooling water is prevented from entering the cooling water jacket on the block side too much, improving the flow straightening function.

FIG. 4 is a bottom view mainly showing the shape of a cooling water jacket in the embodiment. FIG. 2 is a perspective view of a lower-stage head-side cooling water jacket and a block-side cooling water jacket as viewed from above. FIG. 4 is a perspective view mainly showing the block-side cooling water jacket from below. FIG. 4 is a longitudinal sectional front view taken along the line IV-IV in FIG. 1 . FIG. 5 is a schematic cross-sectional view taken along the line V-V in FIG. 4 . FIG. 2 is a side view of the lower-stage head side cooling water jacket and the block side cooling water jacket as viewed from the exhaust side.

Next, an embodiment of the present invention will be described with reference to the drawings. This embodiment is applied to a three-cylinder engine for a vehicle (automobile). In the following, the terms front-rear and left-right are used to specify directions, with the front-rear direction being the crank axis direction and the left-right direction being the direction perpendicular to the crank axis and the cylinder bore axis. With respect to front and rear, the side where the timing chain is located is referred to as the front, and the side where the transmission is located is referred to as the rear.

(1) Description of Structure First, the basic structure of the engine will be described with reference to Figure 4. The engine has, as its basic element, a monoblock-type main body block 3 in which a cylinder block 1 and a cylinder head 2 are integrated, and a crankcase (not shown) is fixed to the underside of the cylinder block 1 by a group of bolts.

The cylinder block 1 is formed with a group of cylinder bores 4 that open downward and a block-side cooling water jacket 5 that surrounds the group of cylinder bores 4, and the space between the cylinder bores 4 and the block-side cooling water jacket 5 forms a cylinder 6. Naturally, the upper end of the cylinder 6 is integrally connected to the cylinder head 2.

The block-side cooling water jacket 5 is roughly shaped like a loop that surrounds the group of cylinder bores 4, with inter-bore spaces 7 between adjacent cylinder bores 4, and the block-side cooling water jacket 5 extends into the inter-bore spaces 7 (see also Figure 5).

The cylinder head 2 is formed with a recess (combustion chamber) 8 that opens toward the cylinder bore 4, and a pair of intake ports 9 and exhaust ports 10 open into the recess 8 from both the left and right sides. The end of the intake port 9 is opened and closed by an intake valve 11, and the beginning of the intake port 9 is opened and closed by an exhaust valve 12. The valves 11 and 12 are biased in the closing direction by a spring 13.

The pair of front and rear intake ports 9 are each opened separately on the intake side (not shown) of the cylinder head 2, and an intake manifold is fixed to the intake side of the cylinder head 2. On the other hand, each pair of exhaust ports 9 communicates with a collecting passage 14 shown in FIG. 6, and the collecting passage 14 opens from one exhaust outlet 15 on the exhaust side of the cylinder head 2. A catalyst case or an exhaust turbocharger is connected to the exhaust outlet 15. The electrode of the spark plug 16 is exposed in the recess 8. It goes without saying that a piston 17 is slidably fitted into the cylinder bore 4.

(2) Cooling structure As shown in Fig. 4, the cylinder head 2 is formed with a lower-stage head-side cooling water jacket 19. As shown in Fig. 6, the cylinder head 2 is also formed with an upper-stage head-side cooling water jacket 20 located above the group of exhaust ports 9 (note that the hatching in Fig. 6 is applied to clarify the shapes of the exhaust passages and the intake ports 8, and is not an indication of a cross section). The lower-stage head-side cooling water jacket 19 has an intake side portion 19a, a center portion (above the bore) 19b, and an exhaust side portion 19c that are connected in series. However, the boundaries between the center portion 19b and the intake side portion 19a and between the center portion 19b and the exhaust side portion 19c are not necessarily clear.

Fig. 2 shows the lower-stage head side cooling water jacket 19. In Fig. 2, a plurality of cylindrical portions 21 protrude from the exhaust side of the lower-stage head side cooling water jacket 19, and these cylindrical portions 21 are connected to the upper-stage head side cooling water jacket 20. That is, the cooling water flows from the lower-stage head side cooling water jacket 19 to the upper-stage head side cooling water jacket 20 through the group of cylindrical portions 21 on the exhaust side, flows vertically from front to back through the upper-stage head side cooling water jacket 20, and is discharged from a cooling water outlet 22 shown in Fig. 6.
Therefore, in this embodiment, the upper stage head side cooling water jacket 20 is disposed only on the exhaust side, but it is possible to form it so that it extends to the intake side as well. The cooling water outlet 22 mainly communicates with the upper stage head side cooling water jacket 20, but also partially overlaps with the lower stage head side cooling water jacket 19. Note that the hatching in Figure 2 is intended to clarify the shape of the intake port 8, and is not an indication of a cross section.

As shown in FIG. 4, the intake side portion of the block side cooling water jacket 5 is integrally connected to the intake side portion 19a of the lower stage head side cooling water jacket 19. On the other hand, the exhaust side portion of the block side cooling water jacket 5 is integrally connected to the exhaust side portion 19c and center portion 19b of the lower stage head side cooling water jacket 19. In FIG. 4, the intake side portion 19a and center portion 19b of the lower stage head side cooling water jacket 19 are separate, but the two are directly connected, for example, at the bore interposition 7.

For example, as shown in FIG. 2, a cooling water inlet 23 is connected to a forward portion of the intake side portion 19a of the head side cooling water jacket 19. The cooling water inlet 23 is formed longitudinally from front to back so as to straddle the first and second cylinders 6 from the front. Cooling water is pumped from a water pump (not shown) to the cooling water inlet 23 via a water supply passage 24. The passage 24 has a stepped crank shape, and cooling water is supplied to the cooling water inlet 23 from the front, but this is due to the positional relationship with the water pump, and a configuration in which cooling water is supplied to the cooling water inlet 23 from directly to the side can also be used.

As shown in Figures 1 and 3, the cooling water inlet 23 has an outward protrusion 23a, but this is formed to facilitate casting and is not related to the flow of cooling water. At the product stage, the protrusion 23a is blocked with a plug.

In this embodiment, the intake side portion 19a of the head side cooling water jacket 19 and the upper end of the block side cooling water jacket 5 are directly connected, but it is also possible to consider the lower end of the cooling water inlet 23 to be hanging on the upper end of the block side cooling water jacket 5. Therefore, in this embodiment, it is also possible to understand that the cooling water inlet 23 is connected to the upper end of the block side cooling water jacket 5. Alternatively, it is also possible to consider that the cooling water inlet 23 is connected across both the lower end of the head side cooling water jacket 19 and the upper end of the block side cooling water jacket 5.

The configurations of the block-side cooling water jacket 5 and the lower-stage head-side cooling water jacket 17 are clearly shown in Figures 1 to 3 and Figures 5 and 6. As described above, the block-side cooling water jacket 5 is basically in the form of a loop surrounding the row of cylinders, but as clearly shown in Figures 1 and 3, its front end (one end) located at the location of the vertically elongated center line that divides the row of cylinders in half when viewed in the axial direction of the cylinder bore is divided in the circumferential direction by a front first notch 25, and its rear end (the other end) is divided by a rear first notch 26.

2 and 3, the center portion 19b of the lower-stage head-side cooling water jacket 19 also has third upward notches 25a, 26a formed symmetrically to the notches 25, 26 of the block-side cooling water jacket 5. Therefore, the center portion 19b of the lower-stage head-side cooling water jacket 19 is thin at the locations of the notches 25, 26 (the wall thickness is thicker).

In FIG. 1, the hatching slanting downwards to the right indicates the block side cooling water jacket 5 and the cooling water inlet 23, and the hatching slanting upwards to the right indicates the lower head side cooling water jacket 19. Also, the hatching in FIG. 3 is intended to clearly show the shape of the intake port 9, and is not a representation of a cross section.

1 and 3, the block-side cooling water jacket 5 surrounding the first cylinder 6 from the front has a front second notch 27 at a position slightly moved from the front end toward the exhaust side, while the block-side cooling water jacket 5 surrounding the third cylinder 6 has a rear second notch 28 at a position slightly moved from the rear end toward the intake side. As can be seen from FIG. 3, the front first notch 25 and the front second notch 27 are covered by the center portion 19b of the lower-stage head-side cooling water jacket 19. The same is true for the rear first notch 26 and the rear second notch 28. Note that each of the notches 25 to 28 is a solid portion, and therefore these can also be called a boss portion that divides the block-side cooling water jacket 5.

These notches 25-28 run the entire height of the block side cooling water jacket 5, but it is also possible to cut out only the upper end. In other words, the block side cooling water jacket 5 can be formed so that only its upper end is connected in a loop. In addition, reference numeral 29 in FIG. 1 indicates the ignition hole placement portion, and reference numeral 30 indicates the valve placement portion. Reference numeral 31 in FIGS. 1 and 2 is a portion for an oil drop hole.

(3) Summary In the above configuration, cooling water flows into the lower head side cooling water jacket 19 and the block side cooling water jacket 5 from the cooling water inlet 23. However, since the cooling water inlet 20 is connected to the lower end of the lower head side cooling water jacket 19 (or the upper end of the block side cooling water jacket 5), excessive cooling of the cylinder 6 is prevented and this contributes to early heating of the main body block 3 and the cooling water (it also contributes to reducing the sliding resistance of the piston by early heating of the oil).

On the other hand, the cooling water flows firmly into the upper end of the block-side cooling water jacket 5, cooling the upper part of the cylinder 6 and preventing excessive temperature rise. This makes it possible to prevent or significantly suppress knocking caused by a rise in intake air temperature.

In addition, because the cooling water inlet 23 is positioned toward the front end of the cylinder head 2, the cooling water flows horizontally from the intake side to the exhaust side in the lower-stage head-side cooling water jacket 19, while also flowing vertically from front to back, and is smoothly guided to the cooling water outlet 22. In this case, because the cooling water inlet 23 is long in the front-to-rear direction so as to straddle the first and second cylinders 6 on the intake side, the cooling water is sent to the lower-stage head-side cooling water jacket 19 so as to be diffused over a wide area. This ensures that the cooling water flows horizontally across the lower-stage head-side cooling water jacket 19.

In addition, since the cooling water inlet 23 discharges toward the bore-to-bore section 7 between the first and second cylinders 6, the bore-to-bore section 7 functions as a buffer section, ensuring that the cooling water flows not only backward but also forward. Therefore, the front end of the first cylinder 6 is also cooled appropriately. In addition, if the cooling water inlet 23 is long in the front-to-rear direction, the robustness of the casting core is increased, which is advantageous in terms of manufacturing.

If the block-side cooling water jacket 5 had a simple loop structure, there is a possibility that the cooling water would flow over the entire height, but by forming the front first notch 25 and the rear first notch 26 as in this embodiment, the flow of the cooling water is blocked by the solid parts of these notches 25, 26, so that the flow of the cooling water is formed only at the upper end of the block-side cooling water jacket 5, and the flow of the cooling water can be eliminated in the portion of the block-side cooling water jacket 5 excluding the upper end. This enhances the heat retention effect of the cooling water and prevents excessive cooling of the cylinders 6.

In addition, the first and third cylinders 6 have improved strength because the outer and inner parts of the block-side cooling water jacket 5 are integrated by the notches 25-28. Also, each cylinder 6 is in the same state as if it had bore-to-bore sections 7 at both the front and rear ends, which helps to suppress distortion.

By forming the second notches 27, 28 at the front and rear ends of the block side cooling water jacket 5 as in the embodiment, the cooling water can be prevented from entering the block side cooling water jacket 5 too much, improving the flow straightening function.

Now, when the cylinder 6 and the cylinder head 2 are integrated, heat is transferred when there is a temperature difference between the cylinder head 2 and the cylinder 6. In this case, the cylinder head 2 becomes hot on the exhaust side, so a temperature difference is also likely to occur between the exhaust side and the intake side of the cylinder 6.

In this regard, in this embodiment, on the intake side, the communication area between the intake side portion 19a of the lower head side cooling water jacket 19 and the bore upper portion 19b is reduced to suppress cooling of the cylinder 6, while on the exhaust side, the center portion 19b and exhaust side portion 19c of the lower head side cooling water jacket 19 are connected to the block side cooling water jacket 5 to improve the cooling performance of the upper portion of the cylinder 6 and the vicinity of the exhaust port 9. Therefore, the temperature difference between the intake side and exhaust side in the upper portion of the cylinder 6 is minimized, and the occurrence of distortion due to heat can be suppressed.

In this embodiment , the flow of cooling water can be optimized by adjusting the number and depth of the notches 25 to 28.

The above describes an embodiment of the present invention, but the present invention can be embodied in many other ways.

The present invention can be embodied in a monoblock engine. Therefore, it can be used industrially.

REFERENCE SIGNS LIST 1 Cylinder block 2 Cylinder head 3 Body block 5 Block side cooling water jacket 6 Cylinder 19 Lower head side cooling water jacket 19a Intake side portion 19b Center portion 20 Upper head side cooling water jacket 22 Cooling water outlet 23 Cooling water inlet 24 Passage 25 Front first notch
25a, 25b third notch
26 Rear first notch 27, 28 Second notch

Claims (2)

A cylinder block is integrated with a cylinder head and has a group of cylinder bores that open downward and a block-side cooling water jacket that surrounds the group of cylinder bores.
The cylinder head is formed with a head-side cooling water jacket that is directly connected to the block-side cooling water jacket,
a cooling water inlet that is long in the cylinder row direction is provided at an upper end of the block side cooling water jacket near one end of the cylinder row, or at a lower end of the head side cooling water jacket near one end of the cylinder row, so as to straddle a first cylinder and a second cylinder as viewed from one end of the cylinder row,
Furthermore, a first notch that is located on the center line of the cylinder row and opens downward, and a second notch that is located circumferentially away from the first notch and opens downward are formed on one end side and the other end side of the cylinder row of the block-side cooling water jacket, respectively .
Monoblock engine. a third notch that is open upward and symmetrical to the first notch is formed on each of the first and second ends of the cylinder row of the head side cooling water jacket;
2. A monoblock engine according to claim 1.

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