Engine intake structure

Abstract

To provide an intake structure of an engine capable of more reliably suppressing vibration of an intake passage.SOLUTION: A throttle valve body is connected to an upper end of an intake manifold, and when a direction parallel to a horizontal direction and along one side surface of an engine body is a lateral direction, the intake manifold curves and extends from the throttle valve body toward one side in the lateral direction and downward. An EGR passage includes a vertical pipe portion extending in a vertical direction and having an upper end connected to a surface on the other side in the lateral direction in an upper portion of the intake manifold, and a connection portion for connecting a lower end of the vertical pipe portion with a lower exhaust passage.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an intake structure for an engine that includes an engine body, an intake passage connected to an intake port that opens on one side of the engine body and through which intake air introduced into the engine body flows, an exhaust passage through which exhaust gas discharged from the engine body flows, and an EGR passage that connects the intake passage and the exhaust passage and returns EGR gas, which is part of the exhaust gas, to the intake passage. [Background technology]

[0002] As an example of a conventional engine intake structure, Patent Document 1 discloses a structure in which a throttle valve body including a throttle valve capable of changing the intake flow area and a drive device for driving the throttle valve is provided in an intake passage, and the throttle valve body is supported by an EGR tube to suppress vibration of the intake passage around the throttle valve body.

[0003] Specifically, in the structure of Patent Document 1, an intake manifold (the intake manifold in Patent Document 1) is connected to an engine body (the cylinder head in Patent Document 1) so as to extend upward from the engine body, and a throttle valve body is connected to the upstream end of the intake manifold so as to be aligned horizontally with the intake manifold. An EGR tube is connected to the upstream end of the intake manifold, and the EGR tube is fixed to the engine body so as to extend downward from the upstream end of the intake manifold. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-141406 Summary of the Invention [Problem to be solved by the invention]

[0005] In the structure of Patent Document 1, the EGR tube supports most of the weight of the throttle valve body. Therefore, it is necessary to increase the rigidity of the EGR tube to suppress vibration of the throttle valve body and, ultimately, vibration of the intake passage. In other words, in the structure of Patent Document 1, if the rigidity of the EGR tube is not sufficiently high, the effect of suppressing vibration of the intake passage is limited. As such, the structure of Patent Document 1 has room for improvement in terms of more reliably suppressing vibration of the intake passage.

[0006] The present invention has been made in view of the above circumstances, and has an object to provide an intake structure for an engine that can more reliably suppress vibrations in the intake passage. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides an intake structure for an engine including an engine body, an intake passage connected to an intake port opening on one side surface of the engine body and through which intake air introduced into the engine body flows, an exhaust passage through which exhaust gas discharged from the engine body flows, and an EGR passage that connects the intake passage and the exhaust passage and returns EGR gas, which is part of the exhaust, to the intake passage, wherein the intake passage includes an intake manifold that extends upward from an opening of the intake port along one side surface of the engine body and has a downstream end of the EGR passage connected to an upper portion thereof, and a throttle valve and throttle valve that are arranged upstream of the intake manifold and are capable of changing a flow passage area of ​​the intake air. and a throttle valve body including a drive device for driving a throttle valve, the exhaust passage comprising a lower exhaust passage disposed below the intake manifold, the throttle valve body being connected to an upper end of the intake manifold, and when a direction parallel to the horizontal direction and along the one side surface of the engine body is defined as a lateral direction, the intake manifold has a shape that extends while curving downward from the throttle valve body to one side in the lateral direction, and the EGR passage comprises a vertical pipe portion that extends in a vertical direction and has an upper end portion connected to a surface on the other side in the lateral direction at the upper part of the intake manifold, and a connecting portion that connects a lower end portion of the vertical pipe portion to the lower exhaust passage. The vertical pipe portion includes an EGR fixing portion fixed to the engine body. (Claim 1).

[0008] According to the present invention, the throttle valve body is connected to the upper end of the intake manifold. This allows the throttle valve body to be stably supported by the intake manifold. The intake manifold has a shape that extends from the throttle valve body while curving downward in one lateral direction, and the EGR passage is connected to the upper part of the intake manifold. This allows the flow path lengths of the EGR gas and intake air to be secured and promotes their mixing without increasing the vertical dimension of the intake manifold, compared to when the intake manifold is shaped to extend straight downward from the throttle valve body.

[0009] Moreover, in the present invention, the EGR passage is connected to a lower exhaust passage provided below the intake manifold at a connecting portion, and has a vertical pipe portion that extends vertically and has an upper end connected to the other horizontal surface of the upper part of the intake manifold. Therefore, vertical vibration of the upper part of the intake manifold can be suppressed. Specifically, in the present invention, the throttle valve body is connected to the upper end of the intake manifold, which has a shape that extends while curving downward on one side of the horizontal direction, making the upper part located on the other horizontal side of the intake manifold prone to vertical displacement. In contrast, the vertical pipe portion restricts displacement of the upper part on the other horizontal side of the intake manifold, thereby suppressing vibration of the upper part.

[0010] As described above, according to the present invention, it is possible to reduce the vertical dimension of the intake manifold, promote the mixing of EGR gas and intake air, and more reliably suppress vibration of the throttle valve body and the intake passage.

[0011] moreover, The vertical pipe portion includes an EGR fixing portion that is fixed to the engine body. do.

[0012] Therefore, according to the present invention The vertical pipe portion is stably supported on the engine body via the EGR fixing portion, which makes it possible to more reliably suppress vibrations of the intake manifold and intake passage supported by the vertical pipe portion.

[0013] In the above-described configuration, the height position of the EGR fixing portion is preferably lower than the height position of the lower end of the intake manifold (see claim 2 ).

[0014] With this configuration, it is possible to effectively suppress vertical displacement of the entire intake manifold, that is, vertical vibration of the entire intake manifold, and ultimately vibration of the intake passage.

[0015] In the above-described configuration, the EGR fixing portion is preferably provided at a position overlapping the throttle valve body in the lateral direction (see claim 3 ).

[0016] According to this configuration, the throttle valve body can be stably supported on the engine body via the vertical pipe portion and the EGR fixing portion.

[0017] In the above-described configuration, preferably, the vertical pipe portion includes an EGR valve body including an EGR valve capable of changing a flow area of ​​the EGR gas and an EGR valve drive device for driving the EGR valve (see claim 4 ).

[0018] According to this configuration, the rigidity of the vertical pipe section is increased, and displacement of the vertical pipe section and therefore displacement of the intake passage can be suppressed, and vibration of the intake passage can be suppressed more reliably.

[0019] In this case, if the intake manifold is made of resin, it is more likely to be displaced than if it is made of metal. Therefore, it is effective to apply the present invention to an intake passage in which the intake manifold is made of resin (claim 5 ).

[0020] The engine body may be a rotary piston engine (claim 6 ). [Effects of the Invention]

[0021] As described above, according to the engine intake structure of the present invention, vibrations in the intake passage can be more reliably suppressed. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a system diagram showing a schematic configuration of an engine according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic side view of the engine as seen from the right. [Figure 3]FIG. 3 is a schematic side view corresponding to FIG. 2 and showing details of components of the intake and exhaust system. [Figure 4] FIG. 2 is a schematic side view of the engine as seen from the rear. DETAILED DESCRIPTION OF THE INVENTION

[0023] (Overall engine configuration) FIG. 1 is a system diagram showing a schematic configuration of an engine to which an intake structure for an engine according to an embodiment of the present invention is applied.

[0024] The engine 1 according to this embodiment is mounted on a vehicle. For example, the engine 1 is mounted on a hybrid vehicle equipped with a motor as a power source for driving, a battery for supplying power to the motor, and a generator for charging the battery, and is used as a device for generating electricity from the generator. The engine 1 includes an engine body 10, an intake passage 3 through which intake air introduced into the engine body 10 flows, an exhaust passage 8 through which exhaust gas discharged from the engine body 10 flows, and an EGR passage 6 which connects the exhaust passage 8 and the intake passage 3 and recirculates EGR gas, which is a part of the exhaust gas, from the exhaust passage 8 to the intake passage 3.

[0025] (Engine body) The engine body 10 of this embodiment is a one-rotor type rotary piston engine (hereinafter referred to as a rotary engine) that has one rotor 11 that rotates around a predetermined rotation axis, an eccentric shaft 12 that extends along the rotation axis of the rotor 11, a rotor housing 13 with an inner circumferential surface that follows a two-node peritrochoid curve, and a pair of side housings 14, 14 that sandwich the rotor housing 13 in the direction along the rotation axis of the rotor 11. The rotor 11 is housed in a rotor housing chamber R that is partitioned by the rotor housing 13 and the two side housings 14, 14, and rotates along the inner circumferential surface of the rotor housing 13 by planetary rotation relative to the eccentric shaft 12.

[0026] The engine body 10 also has a rear holder 20 that is connected to one of the side housings 14 on the opposite side from the rotor housing 13 (in the direction along the rotation axis of the rotor 11) and to which a flywheel 21 is fixed. An oil pan 22 is attached to the bottom of the engine body 10.

[0027] The engine body 10 is mounted on a vehicle with the rotation axis of the rotor 11 and the eccentric shaft 12 extending in a substantially horizontal direction (a direction substantially perpendicular to the up-down direction). Hereinafter, as shown in FIG. 2 and other figures, the direction along the rotation axis of the rotor 11, i.e., the longitudinal direction of the eccentric shaft 12, will be referred to as the "front-rear direction," with the side on which the flywheel 21 is disposed being referred to as the rear and the opposite side being referred to as the front. In the description of the engine 1, the up-down direction when the engine 1 is mounted on a vehicle will be simply referred to as the "up-down direction," and the left-right direction when the engine body 10 is viewed from the rear will be simply referred to as the "left-right direction." Note that FIG. 1 shows a schematic cross-sectional view of the engine body 10 as viewed from the front. In this embodiment, the up-down direction, i.e., the up-down direction when the engine 1 is mounted on a vehicle, corresponds to the "up-down direction" in the claims, and the front-rear direction, i.e., the longitudinal direction of the eccentric shaft 12, corresponds to the "lateral direction" in the claims.

[0028] The engine body 10 is formed with an intake port 15 connected to the intake passage 3 to introduce intake air within the intake passage 3 into the rotor housing chamber R, and an exhaust port 16 connected to the exhaust passage 8 to guide exhaust air from the rotor housing chamber R to the exhaust passage 8. The intake port 15 opens to the upper right side of the rotor housing chamber R, and the exhaust port 16 opens to the lower right side of the rotor housing chamber R. In other words, the engine body 10 is configured so that the rotor 11 rotates clockwise when viewed from the front, and the upper right, upper left, lower left, and lower right regions of the rotor housing chamber R generally serve as regions for the intake stroke, compression stroke, expansion stroke, and exhaust stroke, respectively.

[0029] Two intake ports 15 and two exhaust ports 16 are provided in the engine body 10. The engine body 10 is a side-port rotary engine, and the intake ports 15 and exhaust ports 16 are formed in the side housings 14. That is, one intake port 15 is formed in the upper part of each of the two side housings 14, and each intake port 15 opens at the upper part of the right side surface of each side housing 14. Also, one exhaust port 16 is formed in the lower part of each of the two side housings 14, and each exhaust port 16 opens at the lower part of the right side surface of each side housing 14.

[0030] The engine body 10 is fitted with a fuel injector 17 that injects fuel into the rotor housing R, and an ignition plug 18 that adds fuel to the fuel-air mixture formed in the rotor housing R. In this embodiment, the fuel injector 17 is fitted to face the upper end of the rotor housing R, and the ignition plug 18 is fitted to face the lower left side of the rotor housing R.

[0031] (intake passage) The intake passage 3 is provided with, in this order from the upstream side, an air cleaner 31A that removes foreign matter contained in the intake air, and a throttle valve 41 that can adjust the amount of intake air introduced into the engine body 10 by changing the flow path area of ​​the intake air passing through the intake passage 3.

[0032] Specifically, the intake passage 3 includes, in order from the upstream side, a first intake passage 31, a second intake passage 32, a throttle valve body 40, and an intake manifold 50. The air cleaner 31A is provided in the first intake passage 31, and the throttle valve 41 is provided in the throttle valve body 40. In addition to the throttle valve 41, the throttle valve body 40 includes a throttle valve case 42 that surrounds the throttle valve 41 and defines a passage through which intake air passes, and an actuator 43 that drives the throttle valve 41. The throttle valve 41 is driven by the actuator 43 to open and close the passage defined by the throttle valve case 42. In this embodiment, the actuator 43 that drives the throttle valve 41 is a motor, and hereinafter this actuator 43 will be referred to as a throttle valve motor 43. The throttle valve motor 43 corresponds to the "drive device" in the claims.

[0033] An air flow meter sensor SN1 that detects the flow rate of intake air passing through a portion downstream of the air cleaner 31A in the first intake passage 31 is provided. An intake air temperature sensor SN2 that detects the intake air temperature, which is the temperature of gas passing through the intake manifold 50, is provided in the intake manifold 50.

[0034] The downstream end of the intake manifold 50 is connected to each intake port 15, 15, and the intake air (air) flowing into the first intake passage 31 passes through the air cleaner 31A, the second intake passage 32, the throttle valve case 42, the intake manifold 50, and each intake port 15, 15, and is introduced into the rotor accommodating chamber R.

[0035] (exhaust passage) A purification device 81 for purifying exhaust gas is provided in the exhaust passage 8. The exhaust passage 8 has an exhaust manifold 82 that communicates with each of the exhaust ports 16, 16, and the purification device 81 is disposed downstream of the exhaust manifold 82.

[0036] (EGR passage) The EGR passage 6 communicates with the exhaust manifold 82 and the intake manifold 50. The EGR passage 6 is provided with an EGR cooler 62 that cools the EGR gas, and an EGR valve 71 that can adjust the amount of EGR gas introduced into the intake passage 3 by changing the flow area of ​​the EGR gas passing through the EGR passage 6.

[0037] Specifically, the EGR passage 6 includes, in order from the exhaust passage 8 side, a first EGR passage 61, an EGR cooler 62, a second EGR passage 63, an EGR valve body 70, and a third EGR passage 64. The EGR valve 71 is provided in the EGR valve body 70. The upstream end (in terms of the flow direction of EGR gas) of the first EGR passage 61 is connected to the exhaust manifold 82, and the downstream end (in terms of the flow direction of EGR gas) of the third EGR passage 64 is connected to the intake manifold 50.

[0038] In addition to the EGR valve 71, the EGR valve body 70 has an EGR valve case 72 that surrounds the EGR valve 71 and defines a passage through which EGR gas passes, and an actuator 73 that drives the EGR valve 71. The EGR valve 71 is driven by the actuator 73 to open and close the passage defined by the EGR valve case 72. In this embodiment, the actuator 73 that drives the EGR valve 71 is a motor, and hereinafter, this actuator 73 will be referred to as an EGR valve motor 73. The EGR valve motor 73 corresponds to an "EGR valve drive device" in the claims.

[0039] (Detailed structure) 2 and 3 are schematic side views of the engine 1 as seen from the right. In Fig. 2, the housings of the engine body 10 are shown with chain lines, while bolts and other components are omitted. In Fig. 3, the housings of the engine body 10 are omitted, while bolts and other components are shown. Fig. 4 is a schematic side view of the engine 1 as seen from the rear.

[0040] As described above, each intake port 15 opens to the upper part of the right side surface of each side housing 14, i.e., to the upper part of the right side surface 10A of the engine body 10, and each exhaust port 16 opens to the lower part of the right side surface of each side housing 14, i.e., to the lower part of the right side surface 10A of the engine body 10. The right side surface 10A of the engine body 10, on which each intake port 15 opens and on which these openings are formed, corresponds to "one side surface of the engine body" in the claims.

[0041] The exhaust manifold 82, which communicates with each of the exhaust ports 16, 16, is disposed on the right side of the engine body 10. The exhaust manifold 82 has a shape that extends in the front-to-rear direction. The exhaust manifold 82 is fixed to the lower part of the right side surface 10A of the engine body 10 via an exhaust manifold fixing part 120, in a state in which the exhaust manifold 82 communicates with the two exhaust ports 16, 16. The exhaust manifold 82 corresponds to the "lower exhaust passage" in the claims.

[0042] The portion of the intake passage 3 downstream from the throttle valve body 40 is disposed to the right of the engine body 10. The intake manifold 50 extends upward along the right side surface 10A of the engine body 10 from the openings of the intake ports 15, 15 on the right side surface 10A of the engine body 10. The intake manifold 50 extends to a position above the engine body 10. The lower portion of the intake manifold 50 has a shape that extends in the front-to-rear direction and is in communication with the two intake ports 15, 15.

[0043] The intake manifold 50 has a shape that curves forward (to one side in the front-to-rear direction) and extends downward from its upper end so as to convex forward. The intake manifold 50 also has a shape in which its upper end is shifted rearward relative to its lower end. In this embodiment, the intake manifold 50 is made of resin.

[0044] An intake manifold fixed portion 110 is provided at the bottom of the intake manifold 50 and is fixed to the right side surface 10A of the engine body 10. The intake manifold 50 is fixed to the engine body 10 by fixing the intake manifold fixed portion 110 to the right side surface 10A of the engine body 10 with bolts 112.

[0045] Specifically, one intake manifold fixed portion 110 is provided at each of the four corners of the lower part of the intake manifold 50. As shown in Fig. 4, the upper right side of the engine body 10 is inclined so that the lower part is positioned further right, and the right side surface 10A of the engine body 10 is composed of an inclined surface 210A that forms the upper part and is inclined so that the lower part is positioned further right, and a vertical surface 220A that extends almost straight downward from the lower edge of this inclined surface 210A. Each of the four intake manifold fixed portions 110 has a plate shape that follows the inclined surface 210A, and is fixed to the inclined surface 210A with a bolt 112.

[0046] The throttle valve body 40 is connected to the upper end of an intake manifold 50 at a position above the engine main body 10 .

[0047] Specifically, the throttle valve case 42 has a generally cylindrical shape extending in a predetermined direction. The throttle valve motor 43 has a generally cylindrical outer shape extending in a predetermined direction and is fixed to the outer surface of the throttle valve case 42. The throttle valve body 40 is connected to the upper end of the intake manifold 50 with the throttle valve case 42 extending upward from the upper end of the intake manifold 50 and the throttle valve motor 43 extending in the left-right direction behind the throttle valve case 42. As shown in FIG. 4 , the throttle valve body 40 is connected to the upper end of the intake manifold 50 with the throttle valve motor 43 protruding leftward beyond the left edge of the throttle valve case 42 in a rear view. In this embodiment, the throttle valve case 42 is made of metal.

[0048] The EGR passage 6 is disposed to the right of the engine body 10. The EGR passage 6 is broadly divided into a vertical pipe section 65 extending downward from the rear surface of the upper part of the intake manifold 50 and a connecting section 66 extending forward from the lower end of the vertical pipe section 65 and connected to the exhaust manifold 82. The vertical pipe section 65 is disposed rearward of the intake manifold 50, and the connecting section 66 is disposed between the intake manifold 50 and the exhaust manifold 82. The EGR passage 6 as a whole extends from the rear surface of the upper part of the intake manifold 50, through the area rearward of the intake manifold 50 and between the intake manifold 50 and the exhaust manifold 82, to the upper surface of the front part of the exhaust manifold 82. The vertical pipe section 65 includes the third EGR passage 64, the EGR valve body 70, and the second EGR passage 63, and the connecting section 66 includes the EGR cooler 62 and the first EGR passage 61.

[0049] Specifically, an EGR passage connection portion 59 that protrudes rearward is provided on the rear surface of the upper end portion of the intake manifold 50. The downstream end of the third EGR passage 64, i.e., the downstream end of the EGR passage 6, is connected to this EGR passage connection portion 59, i.e., the rear surface of the upper portion of the intake manifold 50 (the side opposite the convex side of the intake manifold in the front-to-rear direction). The third EGR passage 64 extends downward from the EGR passage connection portion 59. More specifically, the upper portion of the third EGR passage 64 curves from the rear surface of the EGR passage connection portion 59 downward from the EGR passage connection portion 59 so as to convex rearward. The lower portion of the third EGR passage 64 extends substantially straight downward from the lower end of the upper portion of the third EGR passage 64 below the EGR passage connection portion 59.

[0050] The EGR valve body 70 is disposed to the right of the third EGR passage 64. The EGR valve case 72 has a generally cylindrical shape extending in a predetermined direction. The EGR valve motor 73 has a generally cylindrical outer shape extending in a predetermined direction and is fixed to the outer surface of the EGR valve case 72. The EGR valve body 70 is disposed to the right of the third EGR passage 64 in an orientation in which the EGR valve case 72 extends in the vertical direction and the EGR valve motor 73 extends upward from the upper end of the EGR valve case 72. The third EGR passage 64 is connected to the left side surface of the EGR valve case 72 and extends upward from the left side surface of the EGR valve case 72, passing between the EGR valve motor 73 and the right side surface 10A of the engine body 10.

[0051] The second EGR passage 63 is connected to the lower surface of the EGR valve case 72. The second EGR passage 63 extends from the lower surface of the EGR valve case 72 diagonally downward and forward.

[0052] A flange portion 140 is formed integrally with the second EGR passage 63. The flange portion 140 has a generally triangular plate shape (when viewed from the right) extending downward from the second EGR passage 63. An EGR fixing portion 141 for fixing the second EGR passage 63, and therefore the EGR passage 6, to the right side surface 10A of the engine body 10 is provided at the lower end of the flange portion 140.

[0053] The EGR fixing portion 141 is fixed to the right side surface 10A of the engine body 10 by a bolt 142. The EGR fixing portion 141 is fixed to an upper portion of a vertical surface 220A of the right side surface 10A of the engine body 10. That is, in this embodiment, the vertical pipe portion 65 has the EGR fixing portion 141 at its lower end portion, and the vertical pipe portion 65 and the EGR passage 6 are fixed to the engine body 10 via this EGR fixing portion 141.

[0054] The lower ends of the second EGR passage 63 and the flange portion 140 are located below the lower end of the intake manifold 50, and the height (vertical position) of the EGR fixing portion 141 is lower than the height (vertical position) of the lower end of the intake manifold 50. As shown in FIG. 3 , the EGR fixing portion 141 is located directly below the throttle valve body 40 in a side view (viewed from the right), and is disposed at a position overlapping with the throttle valve body 40 in the front-to-rear direction. That is, the EGR fixing portion 141 is provided in a region from the front end position to the rear end position of the throttle valve body 40 in the front-to-rear direction. The chain line L1 in FIG. 3 is a vertical line passing through the center of gravity of the throttle valve body 40. In this embodiment, as shown in FIG. 3 , the EGR fixing portion 141 is provided on a vertical line passing through the center of gravity of the throttle valve body 40 in a side view (viewed from the right). 4, the EGR fixing portion 141 is located directly below the throttle valve body 40 in a rear view (as seen from behind), and is also arranged in a position overlapping with the throttle valve body 40 in the left-right direction. That is, in the present embodiment, the EGR fixing portion 141 is arranged in a position overlapping with the throttle valve body 40 in a top view (as seen from above).

[0055] The EGR cooler 62 has a substantially rectangular parallelepiped shape. The EGR cooler 62 extends forward from the front end of the second EGR passage 63 and is disposed below the intake manifold 50 and above the exhaust manifold 82. More specifically, the EGR cooler 62 is disposed between the intake manifold 50 and the exhaust manifold 82 and is inclined so that the EGR cooler 62 is positioned lower toward the front. The EGR cooler 62 is fixed to the right side surface 10A of the engine body 10 via an EGR cooler fixing portion 130 that extends downward from the underside of the EGR cooler 62. The EGR cooler 62 cools the EGR gas with a coolant, and pipes 62A and 62B are connected to the EGR cooler 62 for introducing and discharging the coolant that flows through it.

[0056] The first EGR passage 61 extends forward from the front end of the EGR cooler 62. Specifically, the first EGR passage 61 is inclined so that it is positioned lower toward the front. The front end of the first EGR passage 61 curves downward and is connected to the upper surface of the front end portion of the exhaust manifold 82. In other words, the first EGR passage 61 extends obliquely upward and rearward from the upper surface of the front end portion of the exhaust manifold 82.

[0057] In this embodiment, the first EGR passage 61, the EGR cooler 62, the second EGR passage 63, the EGR valve case 72, and the third EGR passage 64 are all made of metal.

[0058] (action, etc.) As described above, in the above embodiment, the throttle valve body 40 including the throttle valve motor 43 is connected to the upper end of the intake manifold 50. Therefore, the throttle valve body 40 can be stably supported by the intake manifold 50.

[0059] Here, if the intake manifold 50 were to be shaped to extend straight in the vertical direction and its flow path length were ensured, and the throttle valve body 40 were simply disposed above the intake manifold 50, the vertical dimension of the area of ​​the intake passage 3 occupied by these would be excessively large. In contrast, in the above embodiment, the intake manifold 50 has a shape that extends while curving forward and downward from its upper end, i.e., from the throttle valve body 40. Therefore, the above configuration in which the throttle valve body 40 is disposed above the intake manifold 50 can be realized while preventing the vertical dimension of the area occupied by the intake manifold 50 and the throttle valve body 40 from becoming excessively large, and the flow path length of the intake manifold 50 can be ensured. In the above embodiment, the EGR passage 6 is connected to the upper part of the intake manifold 50, and the flow path length of the intake manifold 50 is ensured, so that the EGR gas introduced into the upper part of the intake manifold 50 can be sufficiently mixed with the intake air before reaching the engine body 10.

[0060] However, as described above, because the intake manifold 50 has a shape that curves forward and downward and the throttle valve body 40 is connected to the upper end of the intake manifold 50, the upper part of the intake manifold 50, more specifically, the portion of the intake manifold 50 located in the upper rear region, is prone to displacement in the vertical direction as shown by arrow Y1 in Figure 3. In particular, in the above embodiment, the intake manifold 50 is made of resin and is therefore prone to displacement.

[0061] In contrast, in the above embodiment, the EGR passage 6 is connected to the exhaust manifold 82 provided below the intake manifold 50. The downstream end of the EGR passage 6 is connected to the rear surface of the upper part of the intake manifold 50, and the EGR passage 6 extends downward from this connection. Specifically, the upper end of the vertical pipe portion 65 of the EGR passage 6, which is made up of the third EGR passage 64, the EGR valve body 70, and the second EGR passage 63, is connected to an EGR passage connection portion 59 provided on the rear surface of the upper part of the intake manifold 50 and extends downward from the EGR passage connection portion 59. In other words, the EGR passage 6, whose displacement is restricted by the exhaust manifold 82, is disposed so as to extend downward from the rear surface of the upper part of the intake manifold 50. Therefore, the EGR passage 6 can restrict vertical displacement of the upper part of the intake manifold 50, i.e., the portion located in the upper rear region of the intake manifold 50. Therefore, according to the above embodiment, the vertical vibration of the intake manifold 50, and hence the vibration of the intake passage 3, can be more reliably suppressed while obtaining the above-mentioned effects.

[0062] In particular, in the above embodiment, the second EGR passage 63 and the vertical pipe portion 65 including it are supported by the engine body 10 via the EGR fixing portion 141 in addition to the exhaust manifold 82. Therefore, the vertical pipe portion 65 can be stably supported by the engine body 10. Therefore, vibration of the intake manifold 50 and the intake passage 3 supported by the vertical pipe portion 65 can be suppressed more reliably.

[0063] In addition, in the above embodiment, the height position of the EGR fixing portion 141 is set lower than the height position of the lower end of the intake manifold 50. Therefore, the vertical pipe portion 65 can effectively suppress vertical displacement and vibration of the entire intake manifold 50, and therefore vibration of the intake passage.

[0064] In the above embodiment, the EGR fixing portion 141 is provided at a position overlapping with the throttle valve body 40 in the front-rear direction. Therefore, the throttle valve body 40 can be stably supported by the engine main body 10 via the vertical pipe portion 65 and the EGR fixing portion 141.

[0065] Furthermore, in the above embodiment, the EGR valve body 70, which includes the EGR valve 71 and the EGR valve motor 73, constitutes part of the vertical pipe section 65. In other words, the EGR valve body 70 is provided in the vertical pipe section 65. This increases the rigidity of the vertical pipe section 65, and further reliably suppresses displacement of the vertical pipe section 65, and consequently displacement and vibration of the intake manifold 50 and the intake passage 3.

[0066] (Variation) In the above embodiment, the engine body 10 is a rotary piston engine, but the type of the engine body 10 is not limited to this.

[0067] In the above embodiment, the intake manifold 50 is made of resin, but the material of the intake manifold 50 is not limited to this. [Explanation of symbols]

[0068] 3 Intake passage 6 EGR passage 8 Exhaust passage 10 Engine body 15 Intake port 16 Exhaust port 40 Throttle valve body 41 Throttle valve 42 Throttle valve case 43 Throttle valve motor (drive unit) 50 intake manifold 65 Vertical pipe section 66 Connecting part 70 EGR valve body 71 EGR valve 73 EGR valve motor (EGR valve drive unit) 82 Exhaust manifold (lower exhaust passage) 141 EGR fixing part

Claims

1. An intake structure for an engine includes an engine body, an intake passage connected to an intake port opening on one side of the engine body and through which intake air introduced into the engine body flows, an exhaust passage through which exhaust gas discharged from the engine body flows, and an EGR passage that connects the intake passage and the exhaust passage and recirculates EGR gas, which is a part of the exhaust gas, to the intake passage, the intake passage includes an intake manifold extending upward from an opening of the intake port along one side surface of the engine body and having an upper portion connected to a downstream end of the EGR passage; and a throttle valve body disposed upstream of the intake manifold and including a throttle valve capable of changing a flow path area of ​​the intake air and a drive device for driving the throttle valve, the exhaust passage includes a lower exhaust passage disposed below the intake manifold, the throttle valve body is connected to an upper end of the intake manifold, when a direction parallel to a horizontal direction and along the one side surface of the engine body is defined as a lateral direction, the intake manifold has a shape that extends while curving downward from the throttle valve body toward one side in the lateral direction, the EGR passage includes a vertical pipe portion that extends in the up-down direction and has an upper end portion connected to the other side surface of the upper portion of the intake manifold in the lateral direction, and a connecting portion that connects a lower end portion of the vertical pipe portion to the lower exhaust passage, An intake structure for an engine, characterized in that the vertical pipe portion has an EGR fixing portion fixed to the engine body.

2. The engine intake structure according to claim 1, An intake structure for an engine, wherein a height position of the EGR fixing portion is lower than a height position of a lower end of the intake manifold.

3. The engine intake structure according to claim 1 or 2, 11. An intake structure for an engine, wherein the EGR fixing portion is provided at a position overlapping with the throttle valve body in the lateral direction.

4. The engine intake structure according to any one of claims 1 to 3, The vertical pipe portion is provided with an EGR valve body including an EGR valve capable of changing a flow path area of ​​the EGR gas and an EGR valve drive device that drives the EGR valve.

5. The engine intake structure according to any one of claims 1 to 4, 1. An engine intake structure, wherein the intake manifold is made of resin.

6. The engine intake structure according to any one of claims 1 to 5, 1. An intake structure for an engine, wherein the engine body is a rotary piston engine.

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