JPH0210277Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to the cylinder head structure of a diesel engine, and particularly to measures for increasing the rigidity of the intermediate portion of the middle deck.

(Prior Art) Conventionally, as a cylinder head structure of this type of diesel engine, as disclosed in, for example, Japanese Utility Model Application Publication No. 57-48, etc., one end of the cylinder head opens into the combustion chamber of the engine (lower surface of the cylinder head). The so-called same-flow type is well known, in which the other ends of the exhaust ports are both opened on one side of the cylinder head.

(Problem to be solved by the invention) By the way, in an in-line multi-cylinder diesel engine in which a plurality of combustion chambers (cylinders) are arranged in series, if the cylinder head structure is the above-mentioned same flow type, each combustion chamber Because the intake and exhaust ports of the cylinder head open on one side of the cylinder head, the glow plug boss and injector boss, which form the mounting holes for attaching the glow plug and fuel injection nozzle (injector), are necessarily located on the cylinder above the combustion chamber. It is arranged on the other side of the head. Therefore, one side of the middle deck, which serves as the upper and lower middle walls of the cylinder head, is covered by the intake and exhaust port walls, and the other side is covered by the glow plug boss and injector boss, which serve as the lower wall of the cylinder head. The middle part, which is located almost directly above the combustion chamber, has low rigidity because it is not connected to the lower deck. the result,
For the entire cylinder head, the bending rigidity in the width direction is lower than the bending rigidity in the cylinder row direction (cylinder head length direction). There was a problem in that the middle deck was easily deformed in a curved manner up and down using both end portions fixed to the cylinder block as fulcrums, and cracks were generated in that portion due to deformation of the middle portion of the low-rigidity middle deck.

The present invention has been developed in view of the above, and its purpose is to improve the cylinder head structure of the above-mentioned same flow type in-line multi-cylinder diesel engine by connecting the walls of the intake and exhaust ports and the glow plug boss or injector boss. By reinforcing the intermediate portion of the middle deck between the two, the deformation of the intermediate portion of the middle deck during engine operation is suppressed, thereby preventing the occurrence of cracks.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, as described above, each of the cylinders is installed in the cylinder head of an in-line multi-cylinder diesel engine in which a plurality of cylinders are arranged in series. One intake and exhaust port and one glow plug boss or injector boss are formed for each cylinder, one end of the intake and exhaust port of each cylinder is opened on one side of the cylinder head, and the other ends are adjacent to each other and are opened at one side of the cylinder head. The opening is offset to one side of the cylinder head relative to the center of the combustion chamber of the cylinder, while the glow plug boss or injector boss is located offset to the other side of the cylinder head relative to the center of each combustion chamber. The target is a cylinder head structure in which the distance between the glow plug boss or injector boss of each cylinder and the intake or exhaust port is longer than the distance between the intake and exhaust ports.

Then, intake and exhaust valve guide bosses are respectively formed above the openings of the intake and exhaust ports of each cylinder to the combustion chamber, and between the valve guide bosses and the glow plug boss or injector boss, the lower surface of the middle deck is connected to the upper wall. A cooling water passage is provided, and a rib connecting both bosses is integrally protruded on the lower surface of the middle deck between the intake valve guide boss and the glow plug or injector boss, and between the exhaust valve guide boss and the glow plug boss or injector boss. The configuration is as follows.

(Function) With the above configuration, in the present invention, ribs are provided protruding from the lower surface of the middle deck between the intake and exhaust valve guide bosses of each cylinder and the glow plug boss or injector boss of each cylinder in the cylinder head. This increases the rigidity of the intermediate portion of the middle deck, and reduces the difference in rigidity between the middle deck and both sides, which are maintained at high rigidity by the walls of the intake and exhaust ports and the glow plug boss or injector boss. Therefore, even if the cylinder head is subjected to gas pressure or heat load in the combustion chamber of the engine, it is difficult to bend or deform the cylinder head at the middle part of the middle deck, thereby preventing the occurrence of cracks at the middle part of the middle deck.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

FIGS. 1 and 2 show the main parts of a swirl chamber type four-cylinder diesel engine according to an embodiment of the present invention. This engine has a cylinder head 1 assembled on a cylinder block 3. Four cylinders 4, 4, . . . (cylinders) each forming a combustion chamber 5 are arranged in series.

The cylinder head 1 includes upper, middle, and lower decks 1a, 1b, and 1c formed at predetermined intervals in the vertical direction.
A cooling water passage 2 (water jacket) through which cooling water flows is formed between the lower deck 1c and the lower deck 1c. The cylinder head 1 also has four intake ports 6, 6, . Four exhaust ports 7, 7, ... for discharging to the outside are provided in each wall portion 6.
The middle deck 1b and the lower deck 1c are integrally connected to each other by holes 7a and 7a. The upstream end of each intake port 6 and the downstream end of the exhaust port 7 are both opened on one side of the cylinder head 1 (the right side in FIG. 1), and the downstream end of each intake port 6 and the upstream end of the exhaust port 7 are The edge is
The cylinder heads 1 are of the same-flow type, and are opened adjacent to each other at positions that are biased towards one side of the cylinder head 1 from the center of the combustion chamber 5 (cylinder center) on the lower surface of the cylinder head 1 facing the combustion chamber 5. It is composed of

In addition, an intake valve guide boss 11 having a valve hole 10 for fitting a valve guide 9 for the intake valve 8 is provided on the wall portion 6a located above the opening of each intake port 6 to the combustion chamber 5. It is formed. Similarly, the wall 7a above the opening of each exhaust port 7 to the combustion chamber 5 is provided with a valve hole 12 for fitting a valve guide (not shown) for the exhaust valve. A guide boss 13 is formed.

On the other hand, the cylinder head 1 facing each combustion chamber 5 is
A recess 15 constituting an auxiliary combustion chamber 14 communicating with the combustion chamber 5 is formed in the lower half of the lower surface corresponding to the other side of the cylinder head. a glow plug boss 17 equipped with a glow plug mounting hole 16 for mounting a glow plug (not shown) facing the inside);
An injector boss 19 having an injector mounting hole 18 for attaching a fuel injection nozzle (not shown) for injecting fuel into the sub-combustion chamber 14 is continuously formed on the outside thereof, and these bosses 17, 1
9 is disposed at a position offset from the center of the combustion chamber 5 to the other side of the cylinder head 1 (to the left in FIG. 1). Further, as shown in FIG. 2, the distance between the glow plug boss 17 or injector boss 9 of each cylinder 4 and the intake or exhaust ports 6, 7 is longer than the distance between the intake or exhaust ports 6, 7.

Further, as a feature of the present invention, a cooling water passage 2 whose upper wall is the lower surface of the middle deck 16 is provided between each of the valve guide bosses 11 and 13 and the corresponding glow plug boss 17 as described above. . Further, a rib 20 extending into the cooling water passage 2 is provided on the lower surface of the middle deck 16 between the intake valve guide boss 11 and the glow plug boss 17, and a rib 20 extending into the cooling water passage 2 is provided on the lower surface of the middle deck 16 between the intake valve guide boss 11 and the glow plug boss 17.
There is a similar rib 2 on the lower surface of the middle deck 16 between
1 are integrally provided so as to connect between both bosses 11, 13, and 17, respectively.

In FIG. 1, 22 is a valve spring that biases the intake valve 8 to close, and 23 is a cylinder head 1.
The insert member 23 is fitted into the recess 15 on the lower surface, and the insert member 23 is formed with a nozzle 24 that communicates the combustion chamber 5 and the sub-combustion chamber 14 .
Further, in FIG. 2, 25, 25, . . . are head bolt holes through which head bolts for joining the cylinder head 1 to the cylinder block 3 are inserted, and the head bolt holes 25, 25, . . . are open at both ends of the cylinder head 1. has been done.

Therefore, in the above embodiment, each valve guide boss 11, 13 in the cylinder head 1
Both bosses 1 are provided on the lower surface of the middle deck 16 between the glow plug bosses 17 corresponding to the bosses 11 and 13.
Since the ribs 20, 21 connecting the bosses 1, 13, 17 are integrally protruded, both the bosses 11, 13,
The middle deck 1 is connected to the lower deck 1c by the walls 6a and 7a of the intake and exhaust ports 6 and 7.
b The difference in rigidity from one side (the right side in FIG. 1) and the other side (the left side in FIG. 1) connected to the glow plug boss 17 and injector boss 19 becomes smaller. As a result, during engine operation, when the cylinder head 1 as a whole tries to bend upward and downward using its both ends (positions of the head bolt holes 25, 25, etc.) as fulcrums due to the gas pressure and heat load in the combustion chamber 5, , middle deck 1b between the two bosses 11, 13, 17
By suppressing the deformation of the cylinder head 1, it is possible to prevent the occurrence of cracks at the intermediate portion of the middle deck 1b of the cylinder head 1.

Also, the rib 2 between the bosses 11, 13, 17 is
0 and 21 protrude into the cooling water passage 2 and the cooling water passage 2 is narrowed, so the flow velocity of the cooling water above the combustion chamber 5 increases accordingly, thereby increasing the cooling effect on the combustion chamber 5. Can be done.

In the above embodiment, each valve guide boss 1
1, 13 and the glow plug boss 17 adjacent to it
Ribs 20, 21 are placed on the bottom surface of the middle deck 1a between the
However, the present invention can also be applied to a cylinder head in which the glow plug boss is formed outside the cylinder head relative to the injector boss, that is, the injector boss is located close to each valve guide boss. In that case, ribs may be provided on the lower surface of the middle deck between the valve guide boss and the injector boss which are close to each other so as to connect both bosses, and the same effects as in the above embodiment can be achieved.

Further, in the above embodiment, an example was explained in which the present invention was applied to a swirl chamber type diesel engine, but it goes without saying that the present invention can also be applied to a diesel engine having other types of combustion chambers.

(Effects of the invention) As described above, according to the invention, in the cylinder head structure of a same-flow type in-line multi-cylinder diesel engine, the gap between the intake/exhaust valve guide boss and the glow plug boss or injector boss of each cylinder is Since ribs are provided protruding from the lower surface of each middle deck, the rigidity of the middle part of the middle deck of the cylinder head is increased by the ribs.
Deformation of the middle deck of the cylinder head due to combustion pressure and heat load in the combustion chamber is effectively suppressed, and therefore cracks can be effectively prevented from occurring at the middle of the cylinder head. Further, since the cooling water passage above the combustion chamber is partially constricted by the ribs on the lower surface of the middle deck, the flow rate of the cooling water in that part is increased, and the cooling effect can be increased.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which FIG. 1 is a longitudinal sectional view of a cylinder head, and FIG. 2 is a sectional view taken along the line -- in FIG. 1... Cylinder head, 1b... Middle deck, 2... Cooling water passage, 5... Combustion chamber, 6... Intake port, 7... Exhaust port, 11, 13... Valve guide boss, 14... Sub-combustion Chamber, 17...Glow plug boss, 19...Injector boss, 2
0,21...rib.

Claims (1)

[Scope of Claim for Utility Model Registration] A cylinder head of an in-line multi-cylinder diesel engine in which a plurality of cylinders are arranged in series, one intake and one exhaust port for each cylinder, and a glow plug boss or injector boss. One end of the intake and exhaust ports of each cylinder is opened to one side of the cylinder head, and the other ends are adjacent to each other and are offset to one side of the cylinder head with respect to the center of the combustion chamber in the cylinder. On the other hand, the glow plug boss or injector boss is formed at a position offset to the other side of the cylinder head with respect to the center of each combustion chamber, and is connected to the glow plug boss or injector boss of each cylinder and the intake or injector boss. The distance to the exhaust port is longer than the distance between the intake and exhaust ports, and intake and exhaust valve guide bosses are formed above the openings of the intake and exhaust ports of each cylinder to the combustion chamber, respectively, and the valve guide bosses are formed above the openings of the intake and exhaust ports of each cylinder to the combustion chamber. A cooling water passage with the lower surface of the middle deck as the upper wall is provided between the intake valve guide boss and the glow plug boss or injector boss, and between the exhaust valve guide boss and the glow plug boss or injector boss. A cylinder head structure for a diesel engine characterized by ribs protruding from the lower surface of the middle deck between the two bosses, each of which connects the two bosses.