JPH0139896Y2 - - Google Patents

Description

[Detailed description of the invention] A. Purpose of the invention: Industrial application field: Mainly used in direct injection multi-cylinder diesel engines for automobiles.

Conventional technology: In direct-injection multi-cylinder diesel engines, the intake manifold is designed to ensure that an equal amount of air is distributed to each cylinder in order to prevent output deviation (variations in output) between cylinders. care is taken on the side of the cylinder head to ensure that a swirl of equal intensity is produced in each cylinder. Factors to consider for the intake manifold include the distance from the air inlet to the intake port and the cross-sectional area of the flow path, and factors to consider for the cylinder head include the shape and orientation of the intake port. In conventional engines, the intake manifold and cylinder head are designed with the above consideration in mind, but in reality, the above output deviation exists.

Problem to be solved by the invention: Since the occurrence of the above output deviation is related to the velocity distribution of the air flowing into the intake port from the intake manifold, the velocity distribution of the air at the entrance of the intake port is as shown in Figure 2. If the velocity distribution is as shown in FIG. 3, it is difficult for an intake port designed to generate the desired swirl in the cylinder, which causes an output deviation. Third
In the figure, O-O is the center line of the inlet of the intake port, V is the flow rate of intake air, V _nax is the maximum value of V, and D is the amount of deviation of the position of V _nax . The offset amount D is particularly noticeable at the intake ports of the front and rear end cylinders, which are located a large distance from the air inlet in the intake manifold. The purpose of this invention is to minimize the deviation amount D of the speed distribution, which is one of the causes of output deviation, and thereby improve the performance of the engine.

B. Means for solving the structural problems of the device: The device according to the present invention has a rectangular cross-sectional flow path section that sends air to the intake port which has a large distance from the air inlet. It is characterized by having a corner portion shaped to give a turning motion to the corner portion.

Effect: The "unbalanced amount D" that was pointed out in relation to Figure 3 in the "Problem to be solved" column is
The above-mentioned flow path section is reduced by the swirl it imparts to the airflow passing through it. FIG. 2 shows an ideal state where D=0. The shape of the corner of the flow path section is determined taking into consideration the length of the section, and subsequent modifications are made while considering the measurement results of the output deviation.

Embodiment: FIG. 1 shows an example of an intake manifold according to the present invention. In this figure, reference numeral 1 indicates an intake port having a large distance from an air introduction port 2 of the intake manifold, and reference numeral 3 indicates a flow path portion with a rectangular cross section that feeds air into the intake port 1. The cross-sectional shape of the channel portion 3 is gradually changed. The large radius of curvature given to the corners of the channel section 3 is designated by R, and the small radius of curvature is designated by r. Corner A, which had been given a large radius of curvature R in the cross section of , gradually decreases its radius of curvature in the direction of air flow, and now has a small radius of curvature r in the cross section of . Corner B, which had been given r, gradually increases its radius of curvature in the traveling direction of the airflow, and now has a large radius of curvature R in its cross section. Also, the corner C, which was given a small radius of curvature r in the cross section of and, gradually increases its radius of curvature and comes to have a large radius of curvature R in the process of being transferred to a cross section from that of. In the flow path portion in which the radius of curvature of the corner portion is changed as described above, the flow path resistance changes at the cross-sectional position where the angular phase is changed by 90 degrees, and therefore exerts a swirling effect on the air flow passing through it. The swirling effect increases as the difference R-r in the radius of curvature increases.

C. Effect of the invention This invention solves the problem that the intake port is unable to generate a swirl of the desired strength due to the unevenness of the velocity distribution at the entrance of the intake port, which causes output deviation between the cylinders. This is to improve the situation. In other words, the intake manifold according to the present invention has the function of improving the velocity distribution of intake air flowing into the intake ports, in addition to its original function of distributing an equal amount of intake air to each cylinder. This reduces output deviation.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an intake manifold according to the present invention, and FIGS. 2 and 3 are drawings showing cases where the flow velocity distribution of intake air at the entrance of the intake port is not biased and when it is biased. 1...Intake port having a large distance from the intake inlet 2, 3...Flow path portion.

Claims (1)

[Scope of utility model registration request] In a type in which air is introduced into a large number of intake ports provided in the cylinder head through an intake flow path with a rectangular cross section, the flow path that sends air to the intake ports that are located at a greater distance from the air introduction port. An intake manifold for a direct injection diesel engine, characterized in that the corners of the parts have a cross-sectional shape that gives a turning shape that reduces output deviation between cylinders.