ENGINE INTAKE DEVICE

Abstract

Engine intake device, comprising: several inlet pipes (23, 24, 25) arranged parallel to each other; and an additional gas supply pipe (30) that introduces an additional gas into air flowing through the inlet pipes (23, 24, 25), wherein a flange connected to an engine block (1A) is located at a downstream end of the multiple inlet pipes (23, 24, 25), wherein the additional gas supply pipe (30) contains: an additional gas inlet (38) which receives an additional gas; a first pipe section (31) extending from the additional gas inlet (38) in a cylinder-row direction; a second pipe section (32) extending from an upstream end of the first pipe section (31) in a direction transverse to the cylinder row direction; and a first branch pipe section (34) and a second branch pipe section (35), which extend on opposite sides from a downstream end of the second pipe section (32) in a cylinder-series direction, wherein the respective inner channels (31A, 32A) of the first pipe part (31) and the second pipe part (32) are formed in a straight line, and the first pipe part (31) and the second pipe part (32) are joined together in such a way that the inner channels (31A, 32A) of the first pipe part (31) and of the second pipe part (32) are bent at right angles, characterized in that, which include several inlet pipes (23, 24, 25): a first inlet pipe (23) with a first distance from the additional gas inlet (38) in the cylinder row direction; a second inlet pipe (24) with a second distance from the auxiliary gas inlet (38) following the first inlet pipe (23); and a third inlet pipe (25) with a third distance from the auxiliary gas inlet (38) following the second inlet pipe (24), wherein the first distance is the shortest from the first, the second and the third distance, the second distance is the next shortest with respect to the first distance, and the third distance is the next shortest to the second distance, the additional gas supply pipe (30) contains: a third pipe section (33), connected to a downstream end of the second branch pipe section (35); and a third branch pipe section (36) and a fourth branch pipe section (37), which extend on opposite sides from a downstream end of the third branch pipe section (33), a first connecting opening (34B) that communicates with the first inlet pipe (23), provided at a downstream end of the first branch pipe section (34), a second connecting opening (36B) that communicates with the second inlet pipe (24), arranged at a downstream end of the third branch pipe section (36); a third connecting opening (37B) which communicates with the third inlet pipe (25), arranged at a downstream end of the fourth branch pipe section (37), wherein the second branch pipe part (35) and the fourth branch pipe part (37) extend in the same direction as one direction of the first branch pipe part (31), the fourth branch pipe section (37) is longer than the third branch pipe section (36), and the shortest distance along an additional gas channel from the additional gas inlet (38) to the first connecting opening (34B) is a distance to the second connecting opening (36B), followed by a distance to the third connecting opening (37B).

Description

Technical area

[0001] The present invention relates to an engine intake device according to the preamble of claim 1. [Technical background]

[0002] A conventional engine intake device is known from JP 2018-251 123 A. This engine intake device is equipped with an EGR device that recirculates a portion of an exhaust gas into an intake path. The EGR device includes a branch passage branching from an EGR passage and introducing an exhaust gas into an intake pipe of an intake manifold. This engine intake device provides a bending angle of a bent portion of the branch passage as the apex angle to suppress inertia of an EGR gas and distribute the EGR gas evenly among all cylinders.

[0003] JP 2019-60 283 A shows an engine intake device according to the preamble of claim 1. In this engine intake device, however, the distribution of the additional gas can be improved in order to reduce, in particular, the influences of inertia during the inflow of the additional gas. [Patent literature] [Patent Document 1] JP2018-251 123 A [Patent Document 2] JP 2019-60 283 A [Disclosure of the invention][Technical problem]

[0004] However, since the engine intake device according to JP 2018-251123 A sets the bending angle of the branch passage at an acute angle, the pressure loss in the bending portion increases, and thus, a maximum flow rate for an exhaust path passing through the bending portion is limited. This leads to a problem in that the distributed exhaust gas amount is unbalanced for all exhaust gas paths due to the presence or absence of the bent portion in the exhaust gas path. In particular, a three-cylinder engine with an odd number of cylinders cannot be configured to have two groups of exhaust paths for every two cylinders, as is the case with, for example, a four-cylinder engine with an even number of cylinders. Thus, it is not easy to ensure uniform distribution of the exhaust gas to all cylinders.

[0005] The present invention has been made in view of the above circumstances, and an object of the invention is to provide an engine intake device that can suppress an increase in pressure loss in an auxiliary gas supply pipe and distribute a large amount of auxiliary gas evenly to all the intake pipes. [Solution to the problem]

[0006] The present invention provides an engine intake device having the features of claim 1 [Advantageous effects of the invention]

[0007] According to the invention, it is thus possible to provide an engine intake device that can suppress an increase in pressure loss in an auxiliary gas supply pipe and distribute a large amount of auxiliary gas to all the intake pipes. [Brief description of the drawings] Fig. 1 is a left side view of an engine incorporating an intake device according to an embodiment of the invention. Fig. 2 is a plan view of an intake manifold and an auxiliary gas supply pipe of the intake device according to the embodiment of the invention. Fig. 3 is a plan view of a lower part of the intake manifold and the auxiliary gas supply pipe of the intake device according to the embodiment of the invention. [Description of the embodiment]

[0008] An engine intake device according to an embodiment of the invention includes: a plurality of intake pipes arranged in parallel to each other; and an auxiliary gas supply pipe that introduces an auxiliary gas into air flowing through the intake pipes, wherein a flange connected to an engine block is located at a downstream end of the plurality of intake pipes, characterized in that the auxiliary gas supply pipe includes: an auxiliary gas inlet that receives an auxiliary gas; a first pipe part extending from the auxiliary gas inlet in a cylinder row direction; a second pipe part extending from an upstream end of the first pipe part in a direction transverse to the cylinder row direction;and a first branch pipe part and a second branch pipe part extending on opposite sides from a downstream end of the second pipe part in the cylinder row direction, wherein respective internal passages of the first pipe part and the second pipe part are formed in a straight line, and the first pipe part and the second pipe part are joined together such that the internal passages of the first pipe part and the second pipe part are bent at right angles. In this way, the engine intake device according to the embodiment of the invention can suppress an increase in pressure loss in the auxiliary gas supply pipe and can evenly distribute a large amount of auxiliary gas to each intake pipe. [Embodiment]

[0009] An engine intake device according to an embodiment of the invention will be described below with reference to the accompanying drawings. Fig. 1 to Fig. 3 are diagrams illustrating the engine intake device according to the embodiment of the invention. Fig. 1 to 3 mean the up-down, front-back and left-right directions for the height direction, the longitudinal direction and the width direction of the engine when installed in the vehicle, wherein a direction orthogonal to the longitudinal direction is a width direction and a height direction of the engine is an up-down direction.

[0010] First, a structure is described. In Fig. 1, an engine 1 is equipped with an engine block 1A.

[0011] The engine block 1A includes a cylinder block 3, a cylinder head 2 connected to the upper part of the cylinder block 3, a head cover 4 provided above the cylinder head 2, and an oil pan 5 connected to the lower part of the cylinder block 3.

[0012] A plurality of cylinders (three, not shown), each housing a piston (not shown) in an up-and-down manner, are formed in the cylinder block 3. Crankshafts (not shown) that convert the up-and-down motion of the pistons into rotational motion are housed in the cylinder block 3, with the crankshafts extending in the left-right direction. The plurality of cylinders are arranged side by side in the left-right direction (hereinafter also referred to as the "cylinder bank direction") in which the crankshafts extend.

[0013] A plurality of combustion chambers (not shown) are located at a base portion of the cylinder head 2. The combustion chambers are located at the top of each cylinder. In the present embodiment, the cylinder head 2 has three combustion chambers arranged in a row in the left-right direction. An exhaust outlet (not shown in the drawings) is located at the front of the cylinder head 2 and serves to discharge exhaust gas.

[0014] After Fig. 1, the engine 1 is equipped with an intake manifold 20. The intake manifold 20 is attached to a side surface rearward of the cylinder head 2 to distribute air that has passed through an air cleaner (not shown) to a plurality of (three in this embodiment) intake ports (not shown) of the cylinder head 2. The engine causes a spark plug (not shown) to ignite and combust the air-fuel mixture consisting of air and fuel taken in from the intake ports, and discharges the exhaust gas after combustion through the exhaust outlet.

[0015] The intake manifold 20 is equipped with a surge tank 21 that temporarily stores air and a manifold part 22 that distributes the air from the surge tank 21 to each intake port of the cylinder head 2.

[0016] The manifold part 22 consists of three inlet pipes 23, 24 and 25, which are arranged parallel to each other.

[0017] The intake manifold 20 is equipped with an auxiliary gas supply pipe 30 that introduces an auxiliary gas (exhaust gas) into the air flowing through the intake pipes 23, 24, and 25. The auxiliary gas supply pipe 30 is located on a top surface of the intake manifold 20 to distribute the auxiliary gas introduced from an exhaust pipe (not shown) to each of the intake pipes 23, 24, and 25 of the intake manifold 20.

[0018] A flange 26 connected to the engine block 1A is located at a downstream end of the plurality of intake pipes 23, 24, and 25. The flange 26 extends in the cylinder row direction. An air inlet 27 for intake of air is located at the upper left end of the surge tank 21. Around the air inlet 27 is a flange 27A to which a throttle body (not shown) is connected.

[0019] In Fig. 2 and Fig. 3, the auxiliary gas supply pipe 30 is structured as a two-way branch: one path to the inlet pipe 23 and another path, with the further path then again branching twice: one path to the inlet pipe 24, the other path to the inlet pipe 25. In this way, the auxiliary gas supply pipe 30 has a structure like a tournament table. Specifically, the auxiliary gas supply pipe 30 includes an auxiliary gas inlet 38 that receives an auxiliary gas, a first pipe part 31 extending from the auxiliary gas inlet 38 in the cylinder row direction, a second pipe part 32 extending from a downstream end of the first pipe part 31 in a direction crossing the cylinder row direction, a first branch pipe part 34 and a second branch pipe part 35 extending on opposite sides from a downstream end of the second pipe part 32 in the cylinder row direction.A flange 38A surrounds the auxiliary gas inlet 38, and an auxiliary gas supply pipe (not shown) is connected to the flange 38A.

[0020] The respective inner channels 31A and 32A of the first pipe part 31 and the second pipe part 32 are formed in the shape of a straight line. The first pipe part 31 and the second pipe part 32 are connected to each other such that the inner channels 31A and 32A bend at right angles. Similarly, the respective inner channels 35A and 33A of the second branch pipe part 35 and the third branch pipe part 33 are formed in a straight line. The second branch pipe part 35 and the third branch pipe part 33 are connected to each other such that their inner channels 35A and 33A bend at right angles. The length of the second pipe part 32 is set to be less than or equal to half the length of the first pipe part 31, and the length of the third pipe part 33 is set to be equal to or less than half the length of the second pipe part 35.This is intended to reduce the length in a direction orthogonal to the cylinder row direction (front-rear direction or longitudinal direction) of the auxiliary gas supply pipe 30 by making the lengths of the second pipe part 32 and the third pipe part 33 relatively shorter. By making the bent or kinked portions immediately in front of the second pipe part 32 and the third pipe part 33 right angles, it is possible to sufficiently suppress the inertia of the auxiliary gas in the cylinder row direction when the gas passes through the straight bent portions, thereby eliminating the need to increase the lengths of the second pipe part 32 and the third pipe part 33. In the present embodiment, the auxiliary gas supply pipe 30 is configured so that their respective upper and lower members form the inner passages 31A and 32A. Fig. 3 shows only the lower element of the auxiliary gas supply pipe 30 in order to visually show the inner channels 31A and 32A and the like.

[0021] According to Fig.3, the respective inner passages 34A and 35A of the first branch pipe part 34 and the second branch pipe part 35 are formed in a straight line shape. The first branch pipe part 34 and the second branch pipe part 35 are joined together at an inclined position so that their downstream ends approach the flange 26 more than their upstream ends. In other words, the first branch pipe part 34 and the second branch pipe part 35 are connected to each other by forming a Y-shaped angle with respect to the second pipe part 32. The first branch pipe part 34 and the second branch pipe part 35 are not completely parallel to each other in the cylinder row direction, but are inclined so that their downstream sides approach the flange 26 side (forward) more than their downstream ends.The auxiliary gas supply pipe 30 includes a comb part 30A projecting toward the downstream end of the second pipe part 32, and this comb part 30A is formed from an inner wall of the first branch pipe part 34 and an inner wall of the second branch pipe part 35.

[0022] The distance from the additional gas inlet 38 to the inlet pipe 23 in the cylinder row direction is the shortest, a distance to the inlet pipe 24 is the second shortest, followed by a distance to the inlet pipe 25. In other words, the inlet pipe 23, as the first inlet pipe, has the shortest distance from the additional gas inlet 38 in the cylinder row direction, the inlet pipe 24, as the second inlet pipe, has the next shortest distance following the inlet pipe 23, followed by the inlet pipe 25 as the third inlet pipe next to the inlet pipe 24. The additional gas supply pipe 30 includes the third pipe part 33, which is connected to a downstream end of the second branch pipe part 35, and a third branch pipe part 36 and a fourth branch pipe part 37, which are located on opposite sides from the downstream end of the third pipe part 33 extend.

[0023] A first connecting port 34B, which communicates with the inlet pipe 23, is located at a downstream end of the first branch pipe part 34. A second connecting port 36B, which communicates with the inlet pipe 24, is located at a downstream end of the third branch pipe part 36. A third connecting port 37B, which communicates with the inlet pipe 25, is located at a downstream end of the fourth branch pipe part 37.

[0024] The second branch pipe part 35 and the fourth branch pipe part 37 run in the same direction as the first pipe part 31.

[0025] The fourth branch pipe part 37 is formed longer than the third branch pipe part 36. A distance along the auxiliary gas passage from the auxiliary gas inlet 38 to the first connecting port 34B is set to be the shortest, a distance to the second connecting port 36B is set to be the next shortest distance, followed by a distance to the third connecting port 37B. Note that the third pipe part 33, the third branch pipe part 36, and the fourth branch pipe part 37 are provided with inner passages 33A, 36A, and 37A, respectively.

[0026] As described above, in the present embodiment, the auxiliary gas supply pipe 30 includes the auxiliary gas inlet 38 for receiving the auxiliary gas, the first pipe part 31 extending from the auxiliary gas inlet 38 in the cylinder row direction, the second pipe part 32 extending from the downstream end of the first pipe part 31 in a direction crossing the cylinder row direction, and the first branch pipe part 34 and the second branch pipe part 35 extending on opposite sides from the downstream end of the second pipe part 32 in the cylinder row direction. The respective inner passages 31A and 32A of the first pipe part 31 and the second pipe part 32 are formed in a straight line. The first pipe part 31 and the second pipe part 32 are joined together in such a way that the respective inner channels 31A and 32A of the first pipe part 31 and the second pipe part 32 bend at right angles.

[0027] Since the first pipe part 31 and the second pipe part 32 are connected to each other in this way, so that the respective internal passages of the first pipe part 31 and the second pipe part 32 bend at right angles, it is possible to suppress the inertia of the auxiliary gas when the auxiliary gas flows from the first pipe part 31 into the second pipe part 32 and passes through the bending part where the respective internal passages of the first pipe part 31 and the second pipe part 32 intersect each other at right angles. Therefore, in the auxiliary gas flowing through the second pipe part 32, the momentum of the flow in the extension direction of the first pipe part 31 due to inertia is suppressed, and the auxiliary gas can flow in the extension direction of the second pipe part 32, making it possible to evenly distribute the auxiliary gas from the second pipe part 32 into the first branch pipe part 34 and the second branch pipe part 35.For this reason, the auxiliary gas supplied to the first branch pipe part 34 and the second branch pipe part 35, which extend on opposite sides from the downstream end of the second pipe part 32 in the cylinder row direction, can be supplied uniformly. Since the first pipe part 31 and the second pipe part 32 are connected such that the inner passages 31A and 32A bend at right angles, it is possible to reduce pressure loss compared to the case where the inner passages 31A and 32A bend at an angle smaller than a right angle.

[0028] As a result, it is possible to suppress an increase in pressure loss in the auxiliary gas supply pipe 30 and to supply a large amount of auxiliary gas evenly to each inlet pipe 23, 24 or 25.

[0029] In the present embodiment, the respective inner channels 34A and 35A of the first branch pipe part 34 and the second branch pipe part 35 are formed in a straight line. The first branch pipe part 34 and the second branch pipe part 35 are connected to each other in an inclined position such that the downstream ends of the first branch pipe part 34 and the second branch pipe part 35 approach the flange 26 more closely than the downstream ends. The crest part 30A, which projects toward the downstream end of the second pipe part 32, is formed from an inner wall of the first branch pipe part 34 and an inner wall of the second branch pipe part 35.

[0030] This makes it possible to evenly distribute the auxiliary gas flowing from the second pipe part 32 into the first branch pipe part 34 and the second branch pipe part 35 due to the comb part 30A. This, in turn, enables even distribution of the auxiliary gas to the first branch pipe part 34 and the second branch pipe part 35, compared to the case where the first branch pipe part 34 and the second branch pipe part 35 are connected in a coaxially and linearly extending position.

[0031] The plurality of intake pipes 23, 24, and 25 constituting the manifold portion 22 of the intake manifold 20 in this embodiment are composed of the intake pipe 23 as the first intake pipe having the shortest distance from the auxiliary gas inlet 38 in the cylinder row direction, the intake pipe 24 as the second intake pipe having the next shortest distance following the intake pipe 23, and the intake pipe 25 as the third intake pipe following the intake pipe 24. The auxiliary gas supply pipe 30 includes the third pipe portion 33 connected to the downstream end of the second branch pipe portion 35, and the third branch pipe portion 36 and the fourth branch pipe portion 37 extending on opposite sides from the downstream end of the third pipe portion 33.

[0032] The first connecting port 34B communicating with the inlet pipe 23 is located at the downstream end of the first branch pipe part 34, the second connecting port 36B communicating with the inlet pipe 24 is provided at the downstream end of the third branch pipe part 36, and the third connecting port 37B communicating with the inlet pipe 25 is located at the downstream end of the fourth branch pipe part 37.

[0033] Furthermore, the second branch pipe part 35 and the fourth branch pipe part 37 extend in the same direction as the first pipe part 31. The fourth branch pipe part 37 is longer than the third branch pipe part 36. The distance along the auxiliary gas channel within the auxiliary gas supply pipe 30 from the auxiliary gas inlet 38 to the first connection opening 34B is set to be the shortest. The distance to the second connection opening 36B is set to be the second shortest distance, followed by the distance to the third connection opening 37B.

[0034] Here, in the case of the engine 1 in the form of a three-cylinder engine, it is possible to adopt a shape in which two pairs of branch parts are symmetrically arranged so that the auxiliary gas supply pipe 30 is used in a manner like a four-cylinder engine, but it has not been easy to distribute the auxiliary gas uniformly due to the shape limitation of the manifold part 22. Even if the right-angled bending or turning part is provided in the auxiliary gas supply pipe 30, as explained above, slight influences of the inertia of the auxiliary gas remain, so that the remaining inertia must be taken into consideration.

[0035] In view of the difficulty in the flow of the auxiliary gas caused by inertia, the length and extension directions of the respective parts of the auxiliary gas supply pipe 30 are configured in the present embodiment to shorten the length of a path through which the auxiliary gas does not flow easily due to inertia, in order to reduce pressure loss and eliminate the influence of inertia. Thus, the auxiliary gas supply pipe 30 can evenly distribute the auxiliary gas to the inlet pipes 23, 24, and 25.

[0036] Although one embodiment of the invention has been disclosed, it will be apparent to those skilled in the art that modifications may be added without departing from the spirit and scope of the invention. All such modifications and equivalents are covered by the appended claims. [List of reference symbols]

[0037] 1 ... engine, 1A ... engine block, 23 ... inlet pipe (first inlet pipe), 24 ... inlet pipe (second inlet pipe), 25 ... inlet pipe (third inlet pipe), 26 ... flange, 27 ... air inlet, 30 ... auxiliary gas supply pipe, 30A ... comb part, 31 ... first pipe part, 31A ... inner duct, 32 ... second pipe part, 33 ... third pipe part, 34 ... first branch pipe part, 34A ... inner duct, 34B ... first connecting port, 35 ... second branch pipe part, 36 ... third branch pipe part, 36B ... second connecting port, 37 ... fourth branch pipe part, 37B ... third connecting port, 38 ... auxiliary gas inlet

Claims

[1] Engine intake device comprising: a plurality of inlet pipes (23, 24, 25) arranged parallel to each other; and an additional gas supply pipe (30) which introduces an additional gas into air flowing through the inlet pipes (23, 24, 25), wherein a flange connected to an engine block (1A) is located at a downstream end of the plurality of inlet pipes (23, 24, 25), wherein the additional gas supply pipe (30) contains: an additional gas inlet (38) receiving an additional gas; a first pipe part (31) extending from the additional gas inlet (38) in a cylinder row direction; a second pipe part (32) extending from an upstream end of the first pipe part (31) in a direction transverse to the cylinder row direction; and a first branch pipe part (34) and a second branch pipe part (35) extending on opposite sides from a downstream end of the second pipe part (32) in the cylinder row direction, wherein respective inner channels (31A, 32A) of the first tube part (31) and the second tube part (32) are formed in a straight line, and the first pipe part (31) and the second pipe part (32) are joined together in such a way that the inner channels (31A, 32A) of the first pipe part (31) and the second pipe part (32) are bent at right angles, characterized by , that, the plurality of inlet pipes (23, 24, 25) contain: a first inlet pipe (23) having a first distance from the additional gas inlet (38) in the cylinder row direction; a second inlet pipe (24) having a second distance from the additional gas inlet (38) subsequent to the first inlet pipe (23); and a third inlet pipe (25) having a third distance from the additional gas inlet (38) following the second inlet pipe (24), the first distance being the shortest of the first, second and third distances, the second distance being the next shorter with respect to the first distance, and the third distance being the next shorter to the second distance, the additional gas supply pipe (30) contains: a third pipe part (33) connected to a downstream end of the second branch pipe part (35); and a third branch pipe part (36) and a fourth branch pipe part (37) extending on opposite sides from a downstream end of the third branch pipe part (33), a first connecting opening (34B) communicating with the first inlet pipe (23), provided at a downstream end of the first branch pipe part (34), a second connection opening (36B) communicating with the second inlet pipe (24), arranged at a downstream end of the third branch pipe part (36); a third connecting opening (37B) communicating with the third inlet pipe (25), arranged at a downstream end of the fourth branch pipe part (37), wherein the second branch pipe part (35) and the fourth branch pipe part (37) extend in the same direction as a direction of the first branch pipe part (31), the fourth branch pipe part (37) is longer than the third branch pipe part (36), and a distance along an additional gas channel from the additional gas inlet (38) to the first connection opening (34B) is the shortest, a distance to the second connection opening (36B) is the second shortest, following a distance to the third connection opening (37B) [2] An engine intake device according to claim 1, wherein respective inner channels (34A, 35A) of the first branch pipe part (34) and the second branch pipe part (35) are each formed in a straight line, the first branch pipe part (34) and the second branch pipe part (35) are connected in an inclined position such that downstream ends of the first branch pipe part (34) and the second branch pipe part (35) approach the flange part (34) compared to upstream ends of the first branch pipe part (34) and the second branch pipe part (35), and on an inner wall of the first branch pipe part (34) and an inner wall of the second branch pipe part (35) a comb part (30A) is formed, which protrudes towards the downstream end of the second pipe part (32).

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