Automotive engine intake manifold

Abstract

To prevent the adhesion of condensed water to a negative pressure takeout port, in an intake manifold having the negative pressure takeout port for a brake booster.SOLUTION: An intake manifold has a first shell-shaped member 1 and a second shell-shaped member 2 overlapped on the first shell-shaped member. A main step part 34a is formed at a point of a depth-part front corner part 33 of a surge tank 6 out of the first shell-shaped member 1, and a first semi-closed space 36 surrounded by a first bulkhead 35 is formed at the main step part 34a. A second bulkhead 42 and a second semi-closed space 43 are formed at even the second shell-shaped member 2. A curved part 39a expanded toward the inside of the surge tank 6 is formed at a side face 39 of the main step part 34, and a step-down concave 40 is formed at a point of the curved part 39a. Condensed water flows down into the convex 40 is stagnated therein, sucked into the surge tank 6 by a suction action which is generated by a flow of intake air intake, atomized, and discharged into a cylinder.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an intake manifold having a negative pressure outlet port for a brake booster, for use in an automobile engine equipped with a brake booster that operates using intake negative pressure. [Background technology]

[0002] In automobiles, the force applied to the brake pedal is amplified by a brake booster, and in passenger cars and small and medium-sized trucks, the brake booster often uses the intake negative pressure. Specifically, a negative pressure output port for the brake booster is provided in the surge tank of the intake manifold, and the negative pressure output port is connected to the brake booster with a hose.

[0003] The problem here is that the intake air, blow-by gas, and EGR gas that flow into the surge tank contain moisture. If this moisture condenses and freezes in the negative pressure extraction port in a low temperature environment, it can cause the brake booster to not work.

[0004] Therefore, measures have been taken to prevent moisture from entering the negative pressure outlet port. For example, Patent Document 1 discloses a method in which a recessed step is formed on the outside of the surge tank, and the negative pressure outlet port is opened in this step.

[0005] Furthermore, in recent years, intake manifolds are often constructed with a hollow structure by joining multiple synthetic resin shell-like members, but Patent Documents 2 and 3 disclose that a partition is provided on the inner surface of one of the multiple shell-like members that make up the intake manifold, which has a negative pressure extraction port, so as to surround the negative pressure extraction port.

[0006] Furthermore, Patent Document 4 discloses a technology in which a raised portion is formed on the inner surface of a shell-shaped member and a negative pressure outlet port is opened on the side of the raised portion, thereby preventing water droplets that run down the inner surface of the shell-shaped member from entering the negative pressure outlet port. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2020-037918 A [Patent Document 2] JP 2010-084641 A [Patent Document 3] JP 2013-133723 A [Patent Document 4] JP 2007-40142 A Summary of the Invention [Problem to be solved by the invention]

[0008] In each of the patent documents, it is said that the negative pressure extraction port is protected by a step portion or a partition wall, etc., and therefore it is possible to prevent moisture from entering the negative pressure extraction port. However, since the negative pressure extraction port opens directly into the inside of the surge tank, it is thought that this does not adequately prevent water droplets contained in the intake air or blow-by gas from entering the negative pressure extraction port.

[0009] The present invention has been made to improve this current situation. [Means for solving the problem]

[0010] The intake manifold of the present invention comprises: In claim 1, "A surge tank with one intake inlet and one brake booster negative pressure extraction port, and a plurality of intake outlet passages branching from the surge tank, The surge tank has two openings facing each other. Shell-shaped member ConnectThey are combined to form a hollow structure. And, A partition wall is provided at the edge of the surge tank so as to protrude from the two shell-shaped members so as to face each other, thereby forming a semi-closed space separated from a main chamber to which the intake outlet passage is opened via a gap, The negative pressure outlet port is formed in one of the two overlapping shell-like members so as to open into the semi-closed space. 」 In this basic configuration, " With the axial direction of the camshaft being the front-rear direction, the intake inlet opens at one end of the front-rear ends of the surge tank, the semi-closed space is formed at the other end of the front-rear ends of the surge tank, and the partition wall constituting the semi-closed space faces the intake inlet side. " It has the following characteristics:

[0011] request In claim 2 In the same basic configuration as claim 1, "The two partitions constituting the semi-closed space are arranged in a generally vertical direction, and a recess (water collection area) where water droplets that run down from the partition or its vicinity can collect is formed at the base or periphery of the lower partition so as to be exposed to the main chamber." The structure is as follows.

[0012] The shape of the recesses can be selected from various types. One example is a depression as in the embodiment, but other shapes such as slit-like grooves, holes, and gutter-like passages surrounded by ribs can also be used. The number and size can be set as desired. In any case, it is preferable that at least a portion of the recesses is exposed to the flow of intake air. It is sufficient for the recesses to have the function of collecting water and dissipating it with the intake air flow, and they do not necessarily need to accumulate water.

[0013] In an intake manifold equipped with a surge tank, the arrangement of the intake inlet varies, but roughly speaking, they can be divided into a type in which the intake inlet opens in a direction intersecting the cam axis, and a type in which the intake inlet opens in the direction of the cam axis. In either case, the position of the recess and the opening direction can be set according to the flow of intake air inside the surge tank.

[0014] As an example of developing claim 2, claim 3 discloses a suitable example applied to a type in which the intake inlet opens in the camshaft direction. That is, the invention of claim 3 is as follows: " The axial direction of the camshaft is the front-to-rear direction, The intake inlet is before Surge tank Before The semi-closed space is open at one end of the rear end of the surge tank. Of the front and rear ends is formed at the other end, The intake air flowing into the surge tank from the intake inlet flows toward the other end where the semi-closed space is formed, and is changed in direction at the other end to flow toward each of the intake outlet passages, Furthermore, in the shell-shaped member in which the recess is formed, a curved portion that bulges toward the main chamber when viewed from the overlapping direction of the two shell-shaped members is formed in a portion exposed to the redirected flow of intake air, and the recess is formed in the curved portion. The structure is as follows. Effect of the Invention

[0015] In the present invention, since the negative pressure outlet port is open to the semi-closed space of the surge tank, even if the intake air, blow-by gas, EGR gas, etc. that flow into the surge tank contain moisture, the partition prevents the moisture from directly entering the negative pressure outlet port. Therefore, it is possible to prevent or significantly suppress the moisture from entering the negative pressure outlet port. As a result, the brake booster can be operated even in a low-temperature environment, improving safety.

[0016] The semi-closed space is formed by protruding partitions from each of the two shell-shaped members that make up the surge tank, so the partitions do not protrude too high, preventing vibrations and noise caused by the partitions. Rather, the partitions reinforce both shell-shaped members, which contributes to increasing the strength of the intake manifold.

[0017] In claim 2, even if condensed water adheres to the partition wall or its surrounding area, the condensed water can be collected in the recess and dispersed by the intake air flow. In other words, the Venturi effect (or ejector effect) allows the intake air flow to suck out the water that has accumulated in the recess. Therefore, it is possible to reliably prevent moisture from entering the negative pressure outlet port.

[0018] Furthermore, by adopting the configuration of claim 3, the recess opens sideways to the flow of intake air, so that the suction action due to the Venturi effect (or ejector effect) acts strongly on the recess, and the suction action (suction action) toward the main chamber can be significantly improved. This ensures that water droplets accumulated in the recess are sucked out and dispersed inside the surge tank. Therefore, the reliability of the effect of preventing moisture from entering the negative pressure outlet port can be improved.

[0019] In this case, the recess is formed in the curved portion, but because the curved portion bulges toward the main chamber of the surge tank, the intake air tends to hit the curved portion strongly and change direction, so the intake air tends to skim the recess and flow, and the Venturi effect (or ejector effect) of the recess becomes prominent. As a result, the reliability of the effect of preventing moisture from entering the negative pressure outlet port can be improved. The moisture that is diffused into the main chamber of the surge tank by the intake air is atomized and discharged to the combustion chamber (cylinder) via each intake outlet passage and intake port.

[0020] Claim 1 and In claim 3 , quasi The partition wall that constitutes the closed space can be used to change the direction of the intake air. In this case, the partition wall is always exposed to the strong flow of intake air, so the generation of condensation water can be prevented or significantly suppressed. This contributes to improving the effect of preventing moisture from entering the negative pressure outlet port. In addition, since the gap opens to the main chamber of the surge tank and is exposed to the flow of intake air, when the brake booster is activated, the air in the semi-closed space can be directly sucked in through the gap. This can be said to improve the responsiveness of the brake booster's operation. [Brief description of the drawings]

[0021] [Figure 1] FIG. 2 is a diagram showing the intake manifold of the embodiment as viewed from diagonally above perpendicular to the cam axis. [Diagram 2] FIG. 4 is a view of the first shell-shaped member positioned on the cylinder head side as viewed obliquely from above. [Diagram 3] FIG. 4 is a perspective view of the first shell-shaped member as viewed obliquely from above. [Figure 4] FIG. 4 is an enlarged view of a main part of FIG. [Diagram 5] 11 is a perspective view of a main part of the second shell-shaped member when turned over and viewed from below. FIG. [Figure 6] FIG. 2 is a view of the intake manifold as viewed from the intake air inflow direction. [Figure 7] 2 is a cutaway perspective view of a main portion of the first shell-shaped member and the second shell-shaped member stacked together, as viewed from the direction of intake air flow. FIG. [Figure 8] 4A to 4C are schematic vertical sectional side views showing the positional relationship between two partition walls. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Next, an embodiment of the present invention will be described with reference to the drawings. This embodiment is applied to an intake manifold for a three-cylinder engine for an automobile. The engine is mounted in the engine room in a horizontal position with the crankshaft facing the vehicle width direction. The exhaust side of the engine faces the forward direction of the automobile. Therefore, the engine is a sideways, front exhaust type. The axis of the cylinder bore is inclined slightly forward toward the forward direction of the automobile.

[0023] In the following, terms such as front-rear, outside-inside, and up-down are used to specify directions, but the front-rear direction is the cam axis direction (crank axis direction), the outside-inside direction is the approximately horizontal direction perpendicular to the cam axis direction, and the up-down direction is the vertical direction. Regarding front and rear, the side of the engine where the timing chain is located is the front, and the side where the transmission is located is the rear. Regarding outside and rear, the side closer to the cylinder head is the back, and the side farther from the cylinder head is the outside. Directions are clearly indicated in the drawings as appropriate.

[0024] (1) Basic structure of the intake manifold As shown in Fig. 8, the intake manifold includes three shell-shaped members, a first shell-shaped member 1, a second shell-shaped member 2, and a third shell-shaped member 3, stacked in a substantially vertical direction, and is formed hollow by joining adjacent shell-shaped members by vibration welding, etc. Therefore, each of the shell-shaped members 1 to 3 is an injection-molded product of synthetic resin.

[0025] 2 shows the first shell-shaped member 1 in its entirety. In this embodiment, the shell-shaped members 1 to 3 have approximately the same shape when viewed from diagonally above (in the overlapping direction). The hatched areas in FIG. 2 are exposed parts of the first shell-shaped member 1, and therefore most of FIG. 1 is taken up by the third shell-shaped member 3. The second shell-shaped member 2 is entirely hidden by the third shell-shaped member 3.

[0026] In Fig. 2, only the first shell-shaped member 1 is shown, and the overlapping surface 4 with the second shell-shaped member 2 is shown by hatching (therefore, the hatching in Fig. 2 does not show a cross section. The same applies to Figs. 3 to 5). The second shell-shaped member 2 and the third shell-shaped member 3 also have overlapping surfaces 4 of the same shape as the first shell-shaped member 1, and the overlapping overlapping surfaces 4 are joined by welding such as vibration welding. Therefore, the second shell-shaped member 2 has inner and outer overlapping surfaces 4. In Figs. 2 and 3, the overlapping surface 4 is shown as a simple flat surface, but in reality, an annular groove 5 is formed in the overlapping surface 4, as shown in Figs. 4 and 5.

[0027] As can be seen from Figure 2, the first shell-shaped member 1 opens on the side opposite (outside) the cylinder head (not shown), and a main recess 7 constituting a surge tank 6 is formed to bulge toward the cylinder head. A mounting seat 9 to which a throttle valve (not shown) is fixed is provided in a protruding manner on a rear wall 8 of the first shell-shaped member 1, and an intake inlet 10 opens into the mounting seat 9. Since the intake inlet 10 opens rearward, the intake air is ejected forward from the intake inlet 10.

[0028] The main recess 7 of the first shell-shaped member 1 extends downward and outward beyond the intake inlet 10, and first to third lower outer grooves 14-16 are formed on the lower exterior of the first shell-shaped member 1 to form the inlet portions of the first to third intake outlet passages 11-13.

[0029] On the other hand, a longitudinal flange 17 that overlaps with the intake side of the cylinder head is formed in the upper inner part of the first shell-shaped member 1, located on the opposite side of the lower outer grooves 14-16 across the main recess 7, and three pairs of intake outlet holes 18-20 (first to third pairs) are opened in the flange 17. The intake outlet holes 18-20 are divided into front and rear by partition walls 18a-20a, respectively, which corresponds to the fact that the intake ports of the cylinder head are separated into pairs.

[0030] As shown in FIG. 1, the third shell-shaped member 3 has first to third outer gutter-shaped portions 21 to 23 for forming the first to third air intake outlet passages 11 to 13, which are formed so as to bulge on the side opposite the main recess 7.

[0031] 1 and the dashed line in FIG. 2, the lower part of the second shell-like member 2 is formed with the lower outer grooves 14-16 of the first shell-like member 1 and the first to third lower outer communication holes 24-26 that overlap with the lower parts of the outer gutter-shaped portions 21-23 of the third shell-like member 3. In addition, although not shown, the upper inner part of the second shell-like member 2 is formed with three upper inner communication holes that overlap with the intake outlet holes 18-19 of the first shell-like member 1 and the upper parts of the outer gutter-shaped portions 21-23 of the third shell-like member 3.

[0032] Furthermore, a first inner gutter-shaped portion 27 (see FIG. 5) and second and third inner gutter-shaped portions that cover the outer gutter-shaped portions 21-23 of the third shell-shaped member 3 from the inside are formed between the upper inner portion communicating hole and the lower outer communicating holes 24-26 of the second shell-shaped member 2. FIG. 5 shows a portion of the first inner gutter-shaped portion 27 as viewed from the surge tank 6 side. The second and third inner gutter-shaped portions are not shown.

[0033] As can be seen from the dotted arrows in FIG. 2, the intake outlet passages 11-13 are disposed on the front side of the paper in FIG. 2, and intake air enters the intake outlet passages 11-13 from below and exits from above as viewed from the paper.

[0034] 1 and 2, the first shell-like member 1 is formed with a plurality of flange-like portions 28 for fixing the intake manifold to the cylinder head. In addition, an EGR gas distribution passage 29 is formed on the overlapping surface 4 at the upper part of the first shell-like member 1 and the second shell-like member 2. The EGR gas distribution passage 29 has a main passage 29a extending from the rear to the front, and two branch passages 29b, 29c branching from the main passage 29a. The end of the main passage 29a is connected to the end of the first intake outlet passage 11, the branch passage 29c located at the rear end is connected to the end of the third intake outlet passage 13, and the branch passage 29b located at the midpoint between the front and rear is connected to the end of the second intake outlet passage 12.

[0035] 2 and 3, a PCV return passage 30 for returning blow-by gas is formed in a longitudinal direction on the overlapping surface 4 at the upper inner part of the first shell-shaped member 1 and the second shell-shaped member 2. An outlet 30a of the PCV passage 30 opens downward toward approximately the middle part of the surge tank 6. On the other hand, an inlet 30b of the PCV return passage 30 opens in a portion of the flange 17 of the first shell-shaped member 1 between the first intake outlet hole 18 and the second intake outlet hole 19.

[0036] The inlet 30b of the PCV passage 30 communicates with an end of the PCV intermediate passage formed in the cylinder head. Therefore, the PCV intermediate passage formed in the cylinder head opens to the intake side of the cylinder head where the flange 17 overlaps.

[0037] (2) Negative pressure outlet port 1, a cylindrical negative pressure outlet port 32 for operating the negative pressure brake booster is formed in a forward-protruding manner on the front wall of the second shell-shaped member 2, located on the opposite side of the surge tank 6 from the intake inlet 10. The structure related to this negative pressure outlet port 32 will be described next.

[0038] As shown in Figures 2 and 3, the surge tank 6 (and the main recess 7 that constitutes it) has a rectangular shape with the front and rear elongated when viewed from the overlapping direction of the shell-shaped members 1 to 3 (roughly diagonally upward and to the side). Therefore, the surge tank 6 has four corners when viewed from the overlapping direction of the shell-shaped members 1 to 3, and as shown in Figures 2 and 3, the negative pressure extraction port 32 is arranged so as to communicate from the front toward the vicinity of the rear front corner portion 33 of the surge tank 6.

[0039] In the first shell-shaped member 1 constituting the surge tank 6, a main step 34a and an auxiliary step 34b rising diagonally upward and outward from the main step 34a toward the second shell-shaped member 2 are formed at a rear front corner portion 33 of the surge tank 6, and a substantially U-shaped first partition wall 35 protruding toward the second shell-shaped member 2 is integrally formed with the auxiliary step portion 34b. Therefore, the surge tank 6 has a first quasi-closed space 36 surrounded by the first partition wall 35.

[0040] The first partition 35 is disposed so as to surround the outlet of the negative pressure outlet port 32 in a side view. The first partition 35 is also set so as to be at approximately the same height as the overlapping surface 4 of the first shell-shaped member 1. The first partition 35 does not reach the inner surface 37 of the front wall of the first shell-shaped member 1. Therefore, a gap 38 through which intake air passes is provided between the first partition 35 and the inner surface 37 of the front wall.

[0041] The main step 34a is formed in such a manner that the rear front corner of the main recess 7 is cut at an angle. Therefore, the intake air that is ejected from the intake inlet 10 and flows forward is guided by the side surface 39 of the main step 34a and changes direction so as to flow downward to the outside, but the side surface 39 of the main step 34a forms a curved portion 39a that bulges generally toward the diagonal direction of the main recess 7 in a side view. Therefore, the intake air hits the curved portion 39a strongly.

[0042] A recess (step-shaped recess) 40 that opens diagonally and upwardly from the main recess 7 is formed in a portion of the main step 34a corresponding to the curved portion 39a, as an example of a recess as defined in the claims. The recess 40 reaches the base of the first partition wall 35. As shown in FIG. 4, the first partition wall 35 protrudes in an oblique direction intersecting with the vertical line (up-down direction). Therefore, water droplets 41 adhering to the outer surface of the first partition wall 35 can be collected in the recess 40. As shown in FIG. 4, the recess 40 has an upper step 40a. Therefore, the recess 40 has two steps.

[0043] As mentioned above, the engine is placed in the engine room in an inclined position so that the exhaust side is tilted forward, and the intake side of the cylinder head to which the flange 17 of the intake manifold is fixed is inclined so that it approaches the cylinder bore as it goes up. For this reason, Figures 2 and 3 are seen from diagonally above, and Figure 4 is a perspective view seen from a direction close to a side view.

[0044] As shown in Fig. 5, a second partition wall 42 is formed in the second shell-shaped member 2 at the rear front corner portion 33 of the surge tank 6, thereby forming a second semi-closed space 43. The second partition wall 42 is connected to two intersecting inner surfaces 44a, 44b of the second shell-shaped member 2. Therefore, the second semi-closed space 43 is open only substantially downward (toward the first semi-closed space 36). The negative pressure output port 32 opens into the second semi-closed space 43, but as shown in Fig. 5, the opening edge of the negative pressure output port 32 is surrounded by a tunnel-shaped enclosure 32a protruding from the inner surface 44a of the side wall.

[0045] In this embodiment, the second partition 42 is disposed offset toward the inside of the surge tank 6 from the first partition 35, and as can be seen from Figs. 6 and 7, the first partition 35 is covered from the inside by the second partition 42. Therefore, a labyrinth shape is formed as shown in Fig. 8(A). As shown in Fig. 7, a gap 45 through which intake air passes is formed between the two partitions 35 and 42. The first semi-closed space 36 and the second semi-closed space 43 form the semi-closed space described in the claims. The surge tank 6 except for the semi-closed spaces 36 and 43 forms the main chamber. Therefore, it can be said that the main recess 7 forms almost the main chamber.

[0046] The relationship between the first partition 35 and the second partition 42 can be such that the second partition 42 and the first partition 36 face each other as shown in Fig. 8(B), or the first partition 35 can be moved closer to the center of the surge tank 6 than the second partition 42 as shown in Fig. 8(C). When the two partitions 35, 42 are shifted as shown in Fig. 8(A) and (C), in either case, one partition can cover the other as shown in (A), or they can be set to the same height as shown in (C).

[0047] As described above, each of the shell-like members 1 to 3 is an injection-molded product, and the partition walls 35, 42 protrude in the die-pulling direction of the shell-like members 1, 2. Therefore, there are no particular problems in manufacturing them.

[0048] (3) Summary As shown by the arrow 46 in Fig. 3, the main flow of intake air flows from the rear to the front inside the surge tank 6, but since the main step 34a and the partitions 35, 42 are arranged at the rear front corner 33 in such a manner as to cut the rear front corner 33 obliquely, the intake air is redirected by the main step 34a and the partitions 35, 42 and flows toward the inlets of the intake outlet passages 11-12. Also, part of the intake air branches off from the main flow 46 and flows toward the inlets of the second intake outlet passage 12 and the third intake outlet passage 13, as shown by the dotted arrow 47 in Fig. 3.

[0049] Furthermore, the negative pressure extraction port 32, which is connected to the brake booster, opens into semi-closed spaces 36, 43 separated by partitions 35, 42, so even if moisture is contained in the intake air or blow-by gas, the moisture will not directly enter the negative pressure extraction port 32.

[0050] In this case, the second semi-closed space 43 to which the negative pressure outlet port 32 is directly open is open only downward and is located above the first semi-closed space 36, so even if moisture-containing intake air enters the first semi-closed space 36, it is difficult for the moisture to enter the second semi-closed space 43. Therefore, it is possible to prevent or significantly suppress moisture from flying into the negative pressure outlet port 32 and turning into water droplets.

[0051] Furthermore, when operating in a low-temperature environment, for example as shown in FIG. 4, moisture contained in the intake air or blow-by gas may condense on the side surface of the first partition 36 and grow into water droplets 41. In this case, the water droplets 41 flow down into the recesses 40 and accumulate therein.

[0052] The intake air hits the side surface 39 of the step portion 33 of the first shell-shaped member 1, changes direction, and flows outward, but because the strong flow of intake air passes through the opening edge of the recess 40, a suction force acts on the recess 40 due to the Venturi effect (or ejector effect), and the accumulated water is sucked out. The sucked out water is atomized by collision with the inner surface of the surge tank 6, and is sent to the cylinder via the intake outlet passages 11-13 and the intake port. This prevents water from entering the negative pressure output port 32, and prevents the brake booster from operating imperfectly due to the negative pressure output port 32 being blocked by freezing.

[0053] In particular, since a curved portion 39a is formed on the side surface 39 of the main step portion 34a and a recess 40 is formed at this curved portion 39a, the intake air hits the curved portion 39a strongly, and the suction effect on the recess 40 is also increased. As a result, the water suction effect is improved, and the effect of preventing water from splashing on the negative pressure extraction port 32 is significantly improved.

[0054] When the brake booster is in operation, as shown by the arrow in Figure 8, air is sucked out from the negative pressure outlet port 32, but the intake air also passes through the gap 45 between the partitions 35 and 42, providing a high sucking effect on the negative pressure outlet port 32. This also results in excellent responsiveness of the brake booster.

[0055] When the outlet 30a of the PCV return passage 30 is located in the middle between the front and rear of the surge tank 6 as in this embodiment, the blow-by gas rides on the main intake flow 46 and collides with the side surface 39 of the main step portion 34a and the partition walls 35, 42, which has the advantage of improving the dispersion of the blow-by gas in the intake air.

[0056] As shown by the dashed line in Fig. 4, a slit 34c may be provided in the main step 34a below the first partition wall 35 as an example of a recess as described in the claims. In this case, water droplets 41 can be collected in the slit 34c and sucked out by the flow of intake air. The slit 34c may be formed instead of the depression 40, or the depression 40 and the slit 34c may be provided together.

[0057] In this embodiment, a gap 38 is provided between the first partition 35 and the inner surface 37 of the front wall, and providing the gap 38 in this manner has the advantage that water droplets 41 generated in the first semi-closed space 36 can be dropped through the gap 38. In other words, there is an advantage that the gap 38 can be used as a water droplet suction space.

[0058] Although the embodiment of the present invention has been described above, the present invention can be embodied in various other ways. For example, the embodiment is a three-part system, but a two-part system is also possible. Also, in the case of the embodiment, it is possible to form the negative pressure outlet port in the first shell-shaped member.

[0059] As an example of a recess, for example, a rib parallel to the inner surface 37 of the front wall can be formed in the portion below the first partition 35 of the main step 34a shown in Figure 4, and a gutter-shaped passage between the rib and the inner surface 37 can be formed as a recess for collecting water. [Industrial Applicability]

[0060] The present invention can be embodied in an intake manifold for an automobile engine, and is therefore industrially applicable. [Explanation of symbols]

[0061] 1 First shell-shaped member 2. Second shell-like member 3. Third shell-like member 4. Layer 6. Surge Tank 7 Main recess 8 Back Wall 9 Throttle body mounting seat 10 Air intake 11~13 Intake outlet passage (branch passage) 21-23 Outer gutter portion forming the intake outlet passage 29 EGR gas distribution passage 30 PCV reflux passage 32 Negative pressure outlet port 33 Back front corner 34a Main section 34b Auxiliary step 35 1st bulkhead 36 First quasi-closed space 39 Side of stepped part 39a Curved section 40 An example of a recess is a depression 42 Second bulkhead 43 Second quasi-closed space 45 Gaps in claims

Claims

1. The system includes a surge tank having one intake inlet and one brake booster negative pressure output port, and a plurality of intake outlet passages branching from the surge tank. The surge tank is formed into a hollow structure by joining two shell-shaped members each having an opening facing each other, A partition wall is provided at an edge of the surge tank so as to protrude from the two shell-shaped members so as to face each other, thereby forming a semi-closed space separated from a main chamber to which the intake outlet passage is opened via a gap, an intake manifold, the negative pressure outlet port being formed in one of the two overlapping shell-like members so as to open into the semi-closed space, With the axial direction of the camshaft being the front-rear direction, the intake inlet opens at one end of the front-rear ends of the surge tank, the semi-closed space is formed at the other end of the front-rear ends of the surge tank, and the partition wall constituting the semi-closed space faces the intake inlet side. An intake manifold for an automobile engine.

2. . The system includes a surge tank having one intake inlet and one brake booster negative pressure output port, and a plurality of intake outlet passages branching from the surge tank. The surge tank is formed into a hollow structure by joining two shell-shaped members each having an opening facing each other, A partition wall is provided at an edge of the surge tank so as to protrude from the two shell-shaped members so as to face each other, thereby forming a semi-closed space separated from a main chamber to which the intake outlet passage is opened via a gap, an intake manifold, the negative pressure outlet port being formed in one of the two overlapping shell-like members so as to open into the semi-closed space, The two partition walls constituting the semi-closed space are arranged in a generally vertical direction, and a recess in which water droplets that have flowed down from the partition wall or its vicinity can collect is formed at the base or periphery of the lower partition wall so as to be exposed to the main chamber. An intake manifold for an automobile engine.

3. With the axial direction of the camshaft being the front-rear direction, the intake inlet opens at one end of the front-rear end of the surge tank, and the semi-closed space is formed at the other end of the front-rear end of the surge tank, The intake air flowing into the surge tank from the intake inlet flows toward the other end where the semi-closed space is formed, and is changed in direction at the other end to flow toward each of the intake outlet passages, Furthermore, a curved portion that bulges toward the main chamber when viewed from the overlapping direction of the two shell-shaped members is formed in a portion of the shell-shaped member in which the recess is formed and that is exposed to the redirected flow of intake air, and the recess is formed in the curved portion.

3. An intake manifold for an automobile engine according to claim 2.

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