Throttle device and intake system of internal combustion engine

Abstract

To provide a throttle device and an intake system of an internal combustion engine, which can simplify a structure, reduce costs, and reduce a passage resistance, and which can increase a flow rate of intake air flowing through an auxiliary intake passage to generate turning flows such as swirl flows or tumble flows in a combustion chamber.SOLUTION: A throttle device applied to an intake system of an internal combustion engine comprises: a body 10 that defines a main passage 12 serving as a part of a main intake passage and an auxiliary passage 17 that branches off from the main passage and serves as a part of an auxiliary intake passage; and a throttle valve 30 that rotates about a predetermined axial line S to open and close the main passage, and closes the main passage upstream of a branch port 17a of the auxiliary passage. The body includes a directional protrusion part 19 that protrudes from an inner wall surface 12a that defines the main passage to direct the intake air flowing through the main passage toward the branch port in a low opening range from a closed state of the throttle valve to a predetermined opening θ.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a throttle device applied to an internal combustion engine mounted on a vehicle, such as a motorcycle, and an intake system of the internal combustion engine.

Background Art

[0002] As an intake system in a conventional internal combustion engine, an intake passage that guides air (intake air) introduced from the outside to a combustion chamber of the internal combustion engine, an intake valve that opens and closes an intake port that forms part of the intake passage, an injector that is disposed near the intake port and injects fuel, a first throttle valve that is disposed in the middle of the intake passage and opens and closes the intake passage, a second throttle valve that is disposed on the downstream side of the first throttle valve and opens and closes the intake passage, and a sub-passage that branches from the intake passage between the first throttle valve and the second throttle valve and joins the downstream side of the injector are known (for example, Patent Document 1).

[0003] In this intake system, at part load, with the downstream second throttle valve closed, only the upstream first throttle valve is opened, and the air introduced from the outside is made to flow into the sub-passage and guided to the downstream passage of the injector, and mixed with the injected fuel, thereby promoting atomization of the fuel.

[0004] However, in the above intake system, since the two throttle valves (the first throttle valve and the second throttle valve) are rotatably provided in a body that defines the intake passage and each is made to perform an opening / closing operation, two throttle valves are required, and also a drive mechanism or the like for opening and closing each throttle valve is required, leading to an increase in the number of parts, higher cost, and complexity of the structure. Further, at full open, since two throttle valves are arranged in the passage, the passage resistance increases compared to the case of a single throttle valve.

[0005] As another intake system, an inlet pipe that defines an intake passage for guiding intake air introduced from the outside into the combustion chamber of an internal combustion engine, an intake valve that opens and closes the intake passage at a position facing the combustion chamber, an injector provided in the inlet pipe for injecting fuel in the middle of the intake passage, a throttle valve provided in the inlet pipe for opening and closing the intake passage, a partition plate that divides the intake passage into an upper intake passage and a lower intake passage on the downstream side of the throttle valve, and an intake distribution valve provided in the inlet pipe at a position downstream of the throttle valve and adjacent to the upstream edge of the partition plate are provided. An intake device is known in which the intake distribution valve is appropriately rotated to change the ratio of air flowing through the upper intake passage and the lower intake passage (for example, Patent Document 2).

[0006] However, in the above intake device, an intake distribution valve is required, and mechanisms for driving the throttle valve and the intake distribution valve are required, leading to increased costs and a more complex structure. Also, when the throttle valve is fully open, the intake distribution valve and the shaft supporting the intake distribution valve obstruct the intake air flow, increasing the passage resistance.

[0007] Furthermore, in order to obtain an intake inertia effect in the low-speed operation region of the engine, a variable intake system is known that includes two intake passages, a high-speed passage with a short passage length and a low-speed passage with a long passage length, and a butterfly-type throttle valve in the branch region of the two intake passages, and switches between the two intake passages (for example, Patent Document 3). In this variable intake system, the inner wall surface of the region where the outer edge of the throttle valve slides is formed in a spherical shape. Therefore, special processing by a dedicated processing machine is required, leading to increased costs such as equipment costs and processing costs. Also, in the opening region where the outer edge of the throttle valve faces the branch port of the low-speed passage, the intake air can flow from the vicinity of the branch port of the low-speed passage to the high-speed passage.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

[0009] The present invention has been made in view of the above circumstances, and its object is to simplify the structure, reduce the cost, reduce the passage resistance, etc., increase the flow rate of the intake air flowing through the sub-intake passage, and generate a swirling flow such as a swirl flow or a tumble flow in the combustion chamber, and to provide a throttle device and an intake system of an internal combustion engine. [Means for Solving the Problems]

[0010] The throttle device of the present invention is a throttle device applied to an intake system of an internal combustion engine including a main intake passage for guiding intake air to a combustion chamber and a sub-intake passage that branches from the middle of the main intake passage and merges into the main intake passage in the vicinity of the combustion chamber. The throttle device includes a body that defines a main passage that forms a part of the main intake passage and a sub-passage that branches from the main passage and forms a part of the sub-intake passage, and a throttle valve that rotates around a predetermined axis to open and close the main passage and closes the main passage upstream of the branch port of the sub-passage. The body includes a directional protrusion that protrudes from the inner wall surface that defines the main passage so as to direct the intake air flowing through the main passage toward the branch port in a low opening region from a state where the throttle valve is closed to a predetermined opening degree.

[0011] In the above throttle device, a configuration may be adopted in which the directional protrusion is formed on the side facing the branch port of the sub-passage.

[0012] In the throttle device described above, the branch port of the sub-passage is formed at a position where the opening area communicating with the main passage upstream of the throttle valve increases according to the opening degree of the throttle valve until the throttle valve reaches a predetermined opening degree, and the directional protrusion is formed at a position facing the branch port on the downstream side of the axis. Such a configuration may be adopted.

[0013] In the throttle device described above, the throttle valve includes a first half-body region and a second half-body region with the axis as a boundary. When the valve is opened, the first half-body region inclines toward the downstream side and faces the branch port side, and the second half-body region inclines toward the upstream side. The directional protrusion is formed on the side facing the branch port of the sub-passage. Such a configuration may be adopted.

[0014] In the throttle device described above, the main passage has a circular cross-section in the region where the throttle valve rotates, and the directional protrusion is formed to protrude from the inner wall surface by a predetermined protrusion amount and curve along the inner wall surface. Such a configuration may be adopted.

[0015] In the throttle device described above, the protrusion amount of the directional protrusion is formed to be smaller than the gap between the outer edge of the second half-body region and the inner wall surface when the throttle valve is positioned at a predetermined opening degree on a plane perpendicular to the axis and including the center line of the main passage. Such a configuration may be adopted.

[0016] In the throttle device described above, the branch port of the sub-passage may be arranged such that its center is located on a plane including the center line of the main passage and the center line of the throttle valve perpendicular to the axis.

[0017] In the throttle device described above, the directional protrusion is formed on the side facing the branch port and includes a planar collision surface against which the intake air flowing through the main passage collides. The collision surface is formed within the range of the intersection region where the virtual passage extending the sub-passage into the main passage intersects the main passage. Such a configuration may be adopted.

[0018] In the throttle device, the sub-passage is formed such that its center line extends perpendicular to the center line of the main passage, and the collision surface of the directional protrusion is formed on the upstream side of the main passage with respect to the center of the intersection region in the extending direction of the main passage. Such a configuration may be adopted.

[0019] In the throttle device, the sub-passage is formed such that its center line extends perpendicular to the center line of the main passage, and the collision surface of the directional protrusion is formed on the upstream side of the main passage with respect to the center of the intersection region in the extending direction of the main passage and is directed so as to expand perpendicular to the center line of the main passage. Such a configuration may be adopted.

[0020] In the throttle device, the sub-passage is formed such that its center line extends downstream at a predetermined inclination angle with respect to the center line of the main passage. Such a configuration may be adopted.

[0021] In the throttle device, the collision surface of the directional protrusion is directed so as to be steeper than the inclination angle of the center line of the sub-passage. Such a configuration may be adopted.

[0022] In the throttle device, the body includes a bypass passage that bypasses the throttle valve, and the branch port of the sub-passage is arranged at a position deviated from the confluence port of the bypass passage. Such a configuration may be adopted.

[0023] In the throttle device, the body includes a detection port that detects the pressure in the main passage downstream of the throttle valve, and the branch port of the sub-passage is arranged at a position deviated from the detection port. Such a configuration may be adopted.

[0024] In the throttle device, the body includes a purge passage that forms a part of a gas passage for guiding fuel evaporation gas to the main intake passage. The introduction port of the purge passage is located upstream of the throttle valve when the throttle valve is closed and is formed to be located immediately downstream of the throttle valve on the way to a predetermined opening degree of the throttle valve. Such a configuration may be adopted.

[0025] The intake system of the internal combustion engine of the present invention includes a main intake pipe that defines a part of the main intake passage for guiding intake air into the combustion chamber of the internal combustion engine, a fuel injection valve that injects fuel into the middle of the main intake passage or into the combustion chamber, a sub-intake pipe that defines a part of the sub-intake passage that branches from the middle of the main intake passage and merges into the main intake passage near the combustion chamber, a gas pipe that defines a part of the gas passage for guiding fuel evaporation gas in the fuel tank into the main intake passage, and a throttle device disposed in the middle of the main intake pipe. As the throttle device, any throttle device having the above configuration is adopted, and the configuration is as described above.

Advantages of the Invention

[0026] According to the throttle device and the intake system having the above configuration, while achieving simplification of the structure, cost reduction, reduction of passage resistance, etc., it is possible to increase the flow rate of the intake air flowing through the sub-intake passage. As a result, it is possible to generate swirling flows such as swirl flow and tumble flow in the combustion chamber, which contributes to the improvement of combustion efficiency.

Brief Description of the Drawings

[0027]

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Mode for Carrying Out the Invention

[0028] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. A throttle device M according to an embodiment is incorporated, for example, in an intake system of an internal combustion engine mounted on a motorcycle. As shown in FIG. 1, the motorcycle includes an internal combustion engine E, a fuel tank T, and other components (not shown).

[0029] The internal combustion engine E includes a cylinder block 1, a piston 2, a cylinder head 3, an intake valve 4a, an exhaust valve 4b, an exhaust pipe 5, an intake system IS, and the like. The cylinder head 3 cooperates with the upper surface of the piston 2 to define the combustion chamber C, and has an intake port 3a that forms part of the main intake passage, a sub-port 3b that forms part of the sub-intake passage, and an exhaust port 3c. It also houses a drive mechanism (not shown) for opening and closing the intake valve 4a and the exhaust valve 4b, a spark plug (not shown), etc.

[0030] The sub-port 3b is formed so as to merge into the intake port 3a on the immediate upstream side of the intake valve 4a. That is, the sub-intake passage (sub-port 3b) has a confluence port 3b1 that merges into the main intake passage (intake port 3a) on the upstream side of the intake valve 4a. The confluence port 3b1 of the sub-port 3b is oriented in a direction that generates a swirl flow (lateral vortex) in the combustion chamber C. Specifically, the confluence port 3b1 of the sub-port 3b merges into the intake port 3a from an oblique direction, and is formed such that the intake air flows into the combustion chamber C in the tangential direction of the inner wall surface.

[0031] The intake system IS includes the intake port 3a and the sub-port 3b of the cylinder head 3, an air cleaner Ac for sucking in outside air, a main intake pipe Ip, a sub-intake pipe Sp, a fuel injection valve Iv disposed in the middle of the main intake pipe Ip, a throttle device M disposed in the middle of the main intake pipe Ip on the upstream side of the fuel injection valve Iv, a gas pipe Gp connecting the fuel tank T and the throttle device M, and a charcoal canister Cc disposed in the middle of the gas pipe.

[0032] The main intake pipe Ip is formed of a metal, resin material, etc., and defines a main intake passage Ip1 having a substantially circular cross-section for passing the intake air sucked in by the air cleaner Ac. It is disposed so as to be interposed between the air cleaner Ac and the intake port 3a of the cylinder head 3. The sub-intake pipe Sp is formed of a metal, resin, or rubber material, etc., and defines a sub-intake passage Sp1 having a circular cross-section for passing the intake air. Its upstream end is connected to a connector 17b that defines part of a sub-passage 17 provided in the throttle device M, and its downstream end is connected to a connector (not shown) that leads to the sub-port 3b of the cylinder head 3. The fuel injection valve Iv is arranged in the main intake pipe Ip and injects fuel into the main intake passage Ip1 near the intake port 3a side.

[0033] The gas pipe Gp defines a gas passage Gp1, connects the fuel tank T and the charcoal canister Cc, and is arranged to connect the charcoal canister Cc and a connector 18b that defines a part of the purge passage provided in the throttle device M. The charcoal canister Cc houses activated carbon that temporarily adsorbs fuel evaporation gas led from the fuel tank T, guides the stored fuel evaporation gas to the gas passage Gp1, and takes in outside air according to the internal pressure.

[0034] As shown in FIGS. 2 to 6, the throttle device M includes a body 10, a rotating shaft 20 centered on an axis S, a throttle valve 30, a drive unit 40 that drives the throttle valve 30 to open and close, an adjustment valve 50, and a sensor unit U. Here, the sensor unit U includes an angular position sensor 60, a pressure sensor 70, a temperature sensor 80, and a circuit board (not shown). In addition, when the throttle device M is applied to the intake system IS, as shown in FIGS. 2 and 3, the connector 18b that defines the purge passage 18 is assembled so as to be arranged on the upper side in the vertical direction.

[0035] The body 10 is formed of a metal material such as aluminum or a resin material, and includes an upstream connection portion 11a, a downstream connection portion 11b, a main passage 12, a shaft hole 13 through which the rotating shaft 20 passes, a bypass passage 14, a housing portion 15 that houses the adjustment valve 50, an inspection port 16, a sub-passage 17, a purge passage 18, and a directional protrusion 19.

[0036] The upstream connection portion 11a is connected to the upstream main intake pipe Ip connected to the air cleaner Ac, and the downstream connection portion 11b is connected to the downstream main intake pipe Ip connected to the peripheral region of the intake port 3a of the cylinder head 3 of the internal combustion engine E. 1, the lower connection part 11b is shown connected to a relatively long downstream main intake pipe Ip, but the lower connection part 11b in the form shown in Fig. 3 may be connected to a main intake pipe Ip that is located a short distance from the cylinder head 3, or may be directly joined to the joint surface of the cylinder head 3. In this case, an auxiliary intake pipe Sp that is shorter than the one shown in Fig. 1 is also used as the auxiliary intake pipe Sp.

[0037] The main passage 12 functions as a part of the main intake passage that guides the intake air to the combustion chamber C, and is formed into a cylindrical shape that has a circular cross section centered on a center line L1 perpendicular to the axis S and extends in the direction of the center line L1. As shown in Fig. 7, the main passage 12 is formed into a conical surface shape in which the passage area increases from a predetermined region where the throttle valve 30 is rotatably disposed toward the upstream connection part 11a and the downstream connection part 11b. Here, the predetermined region where the throttle valve 30 is rotatably disposed is bored from the upstream side by a processing machine so as to form a cylindrical inner wall surface 12a. 5, the shaft hole 13 is formed as a circular hole so that the rotating shaft 20 can be passed through freely rotatably around the axis S, and an annular recess 13a into which a lip-type seal Rs is fitted is formed on the outer side in the direction of the axis S. Note that the shaft hole 13 may be provided with a bush as a bearing that rotatably supports the rotating shaft 20.

[0038] As shown in FIGS. 5 and 8, the bypass passage 14 is made up of an upstream passage 14a branching off from the main passage 12 upstream of the throttle valve 30, a downstream passage 14b joining the main passage 12 downstream of the throttle valve 30, and a communication passage 14c interposed between the upstream passage 14a and the downstream passage 14b and whose passage area is adjusted by an adjustment valve 50. That is, the bypass passage 14 branches off from the main passage 12 at a branch port 14a1 located upstream of the throttle valve 30 to introduce intake air, and then bypasses the throttle valve 30 and discharges the intake air into the main passage 12 at a junction port 14b1 located downstream of the throttle valve 30.

[0039] As shown in FIGS. 5 and 8, the accommodation portion 15 is an area that reciprocally accommodates the valve body 51 of the regulating valve 50, and also functions as a communication passage that connects the upstream passage 14a and the downstream passage 14b. As shown in FIGS. 5 and 6, the detection port 16 opens into the main passage 12 on the downstream side of the throttle valve 30, and is formed such that the pressure sensor 70 provided in the sensor unit U is exposed to the intake air in the main passage 12.

[0040] The sub-passage 17 forms a part of the sub-intake passage. As shown in FIGS. 4 and 7, it has a circular cross-section, branches from the main passage 12 on the downstream side of the throttle valve 30, and extends from the branch port 17a, which is the starting point of the sub-passage 17, over a predetermined length in a direction in which its center line L2 forms a predetermined angle (here, a perpendicular direction) with respect to the center line L1 of the main passage 12. Further, the sub-passage 17 is also defined in an L-shaped connector 17b in which its downstream region is fitted to the body 10 and the sub-intake pipe Sp is connected.

[0041] As shown in FIG. 9, the branch port 17a of the sub-passage 17 is arranged in the main passage 12 to be located downstream by a distance ΔL from the axis S of the rotation shaft 20, and its center (center line L2) is arranged to be located on a plane including the center line L3 of the throttle valve 30 perpendicular to the center line L1 of the main passage 12 and the axis S of the rotation shaft 20, as shown in FIGS. 4 and 8. In this way, since the branch port 17a is arranged at the center of the main passage 12 and the throttle valve 30 in the axial direction of the axis S, the intake air can be efficiently guided toward the sub-passage 17. Also, as shown in FIG. 3, the branch port 17a of the sub-passage 17 is arranged at a position deviated from the confluence port 14b1 of the bypass passage 14, and as shown in FIG. 7, it is arranged at a position deviated from the detection port 16. In this way, since the branch port 17a is arranged at a position deviated from the confluence port 14b1 and the detection port 16, the influence between them can be prevented, and each function can be achieved.

[0042] Furthermore, as shown in FIG. 9, the branch port 17a of the auxiliary passage 17 is located on the downstream side of the throttle valve 30 in the fully closed state where the throttle valve 30 is closed, that is, it is blocked from the main passage 12 upstream of the throttle valve 30 in the fully closed state, and until the throttle valve 30 reaches a predetermined opening degree θ, an opening area A communicating with the main passage 12 upstream of the throttle valve 30 is formed at a position where it increases according to the opening degree of the throttle valve 30. Specifically, in FIG. 7, when the throttle valve 30 rotates clockwise from the fully closed position, the opening area A of the branch port 17a communicating with the main passage 12 upstream of the first half body region 30a of the throttle valve 30 gradually increases as the throttle valve 30 rotates, and when it rotates to the predetermined opening degree θ, the opening area A of the branch port 17a becomes maximum.

[0043] The purge passage 18 forms a part of a gas passage that guides fuel vapor gas to the main intake passage, and as shown in FIGS. 4 and 7, it is provided with an inlet 18a for introducing fuel vapor gas into the main passage 12. Further, in the connector 18b where the upstream region of the purge passage 18 is fitted to the body 10 and the gas pipe Gp is connected, the upstream region of the purge passage 18 is also defined. Also, as shown in FIG. 9, the inlet 18a of the purge passage 18 is located upstream of the throttle valve 30 in the state where the throttle valve 30 is closed, and is formed so as to be located immediately downstream of the throttle valve 30 during the process when the throttle valve 30 reaches the predetermined opening degree θ. By arranging the inlet 18a at such a position, when the throttle valve 30 is in the low opening degree region, as the flow velocity of the intake air in the main passage 12 increases, the fuel vapor gas is actively sucked out from the inlet 18a and is guided to the auxiliary passage 17.

[0044] The directional protrusion 19 is integrally formed when the body 10 is molded by a mold, and as shown in FIGS. 4, 7, and 9, it protrudes from the inner wall surface 12a on the side facing the branch port 17a of the auxiliary passage 17 on the inner wall surface 12a defining the main passage 12 on the downstream side of the axis S, and is formed to include a planar collision surface 19a against which the intake air flowing through the main passage 12 collides. Then, the guiding protrusion 19 is configured to direct the intake air flowing through the main passage 12 toward the branch port 17a of the sub-passage 17 in a low opening region from the state where the throttle valve 30 is closed to a predetermined opening θ.

[0045] Further, as shown in FIGS. 4 and 8, the guiding protrusion 19 protrudes from the inner wall surface 12a of the main passage 12 toward the center line L1 by a predetermined protrusion amount and is formed to curve along the inner wall surface 12a. Here, as shown in FIG. 9, the protrusion amount H of the guiding protrusion 19 is formed to be smaller than the gap C between the outer edge of the second half body region 30b of the throttle valve 30 and the inner wall surface 12a on a plane perpendicular to the axis S and including the center line L1 of the main passage 12 when the throttle valve 30 is positioned at the predetermined opening θ. Here, the protrusion amount H is preferably formed to be equivalent to the gap Cm when the throttle valve 30 is positioned at a low opening θm (here, in the vicinity of about 20 degrees) smaller than the predetermined opening θ.

[0046] Also, as shown in FIG. 10, the collision surface 19a of the guiding protrusion 19 is formed within the range of the intersection region Ca where the virtual passage Vp extending the sub-passage 17 into the main passage 12 intersects the main passage 12. Here, the guiding protrusion 19 is formed on the upstream side of the main passage 12 from the center (center line L2 of the sub-passage 17) of the intersection region Ca in the extending direction (center line L1 direction) of the main passage 12. Furthermore, the collision surface 19a of the guiding protrusion 19 is oriented to be steeper than the inclination angle when the throttle valve 30 is positioned in the low opening region. Specifically, it is oriented to expand perpendicular to the center line L1 of the main passage 12. Note that the collision surface 19a may be simultaneously machined by a machining machine (machining tool) for boring to be a vertical plane during the boring process of the main passage 12.

[0047] According to the directional protrusion 19 having the above-described configuration, in the low opening region where the throttle valve 30 reaches a predetermined opening degree θ from the closed state, the intake air flowing through the main passage 12 can be collided with the collision surface 19a to change the direction and directed toward the branch port 17a of the sub-passage 17. Further, since the directional protrusion 19 is formed so as to integrally protrude from the inner wall surface 12a when the body 10 is molded by a mold, dedicated machining or the like is not required, which contributes to cost reduction.

[0048] The rotary shaft 20 is formed of a metal material or the like to have a circular cross section and extend in the axial direction S. As shown in FIGS. 4 and 5, a slit 21 for fitting the throttle valve 30, two screw holes 22, a connecting portion 23 for connecting the drive unit 40 at one end side, and a bottomed cylindrical portion 24 are provided in the central region. Further, a double-width portion 21a is formed on the outer periphery of the region of the slit 21 in order to reduce the passage resistance in the main passage 12. The connecting portion 23 is provided with a double-width portion so as to be fitted to integrally rotate the drum 41 of the drive unit 40. The bottomed cylindrical portion 24 is provided with a permanent magnet 24a on the inner peripheral surface and is formed so as to non-contactingly accommodate the columnar angular position sensor 60 of the sensor unit U inside.

[0049] Then, with the rotary shaft 20 passed through the shaft hole 13 of the body 10, the throttle valve 30 fitted into the slit 21 is fastened by the screw b, thereby holding the throttle valve 30 so as to be freely opened and closed. Further, the outer peripheral surface of the rotary shaft 20 is sealed by a lip type seal Rs outside the shaft hole 13 in the axial direction S.

[0050] The throttle valve 30 is formed of a metal material or the like into a substantially disc shape, and as shown in FIGS. 4 and 5, is provided with a circular hole 31 through which the screw b passes. After the rotary shaft 20 is passed through the shaft hole 13, it is passed through the slit 21 and fixed to the rotary shaft 20 by the screw b, and is arranged to open and close the main passage 12. That is, the throttle valve 30 is fixed to the rotary shaft 20 and forms a flat butterfly valve including a first half body region 30a and a second half body region 30b with the axis S of the rotary shaft 20 as a boundary. Further, when the throttle valve 30 is driven by the drive unit 40 to open the valve, that is, when moving from the fully closed position to the fully open position, as shown in FIG. 9, the first half body region 30a inclines toward the downstream side of the main passage 12 and faces the branch port 17a of the sub passage 17 while becoming parallel to the center line L1, and the second half body region 30b changes its posture so as to be parallel to the center line L1 while inclining toward the upstream side of the main passage 12.

[0051] And, in the low opening region where the throttle valve 30 reaches a predetermined opening θ from the closed state, as shown in FIG. 11, the intake air flowing into the main passage 12 upstream of the throttle valve 30 is guided by the first half body region 30a that inclines toward the downstream side, directed toward the branch port 17a, and flows into the sub passage 17. At the same time, the intake air flowing into the back side of the first half body region 30b that inclines toward the upstream side is directed toward the branch port 17a by the directing protrusion 19 (collision surface 19a) and flows into the sub passage 17.

[0052] As shown in FIGS. 2, 3, and 5, the drive unit 40 rotationally drives the rotary shaft 20 around the axis S, and includes a drum 41 connected and fixed to the connecting portion 23 of the rotary shaft 20, and a coil spring 42 disposed between the drum 41 and the body 10 around the rotary shaft 20. The drum 41 includes a locking hole 41a to which a wire connected to the throttle grip is locked, and a contact lever 41b that also serves as a locking portion for locking the coil spring 42. As shown in FIG. 3, one end portion 42a of the coil spring 42 is locked to the locking portion 41b of the drum 41, and the other end portion (not shown) is locked to a locking portion (not shown) of the body 10, and exerts a rotational biasing force in the direction in which the throttle valve 30 closes. The contact lever 41b comes into contact with an adjustment screw (not shown) provided on the body 10 by the rotational biasing force of the coil spring 42. Therefore, by appropriately adjusting the feed amount of the adjustment screw, the valve opening degree of the throttle valve 30 at the stop position can be set to a desired position.

[0053] As shown in FIGS. 2 and 8, the regulating valve 50 includes a valve body 51, an electromagnetic actuator 52 having a lead screw for driving the valve body 51 to reciprocate in a direction parallel to the axis S, and a pressing member 53 for fixing the electromagnetic actuator 52 to the body 10. And the regulating valve 50 is configured to adjust the flow rate of the intake air flowing through the bypass passage 14 by increasing or decreasing the passage area of the bypass passage 14 (communication passage) in the engine idle operation region.

[0054] As shown in FIG. 5, the angular position sensor 60 is provided in the sensor unit U, formed in a cylindrical shape with a Hall element embedded therein, and cooperates with a permanent magnet 24a disposed in a bottomed cylindrical portion 24 coupled to the rotary shaft 20 to detect the rotation angle of the rotary shaft 20.

[0055] As shown in FIG. 6, the pressure sensor 70 is provided in the sensor unit U, and includes a pressure receiving portion such as a diaphragm having, for example, a semiconductor strain gauge, a protective cover, etc. And the pressure sensor 70 detects the pressure of the intake air through a detection port 16 communicating with the main passage 12. Here, since the detection port 16 is formed at a position away from the branch port 17a of the sub-passage 17 in the direction of the center line L2 and in the circumferential direction around the center line L1, the pressure of the intake air can be detected without being affected by the intake air flow in the vicinity of the branch port 17a.

[0056] The temperature sensor 80 is for detecting the temperature of the intake air flowing through the main passage 12. As shown in FIG. 6, it is provided in the sensor unit U and is a lead type sensor including a temperature sensing element 81 such as a thermistor. And the temperature sensor 80 is housed in a cylindrical portion 82 protruding from the main body of the sensor unit U and is arranged to protrude into the main passage 12 upstream of the throttle valve 30 to detect the temperature of the intake air.

[0057] In the throttle device M having the above configuration, the function and effect of the directional protrusion 19 will be described below with reference to FIGS. 12 to 14 in comparison with the case where the directional protrusion 19 is not provided (comparative example). FIG. 12 shows the result of simulating the flow rate of the intake air flowing through the sub-passage 17. According to this result, in the low opening region where the throttle valve 30 opens from the fully closed position where it is closed and reaches a predetermined opening θ (here, about 37 degrees), the flow rate in the throttle device M of the present invention increases compared to the comparative example. That is, by providing the directional protrusion 19, the flow rate of the intake air flowing through the sub-passage 17 can be increased.

[0058] Further, FIG. 13 shows the result of simulating the ratio of the flow rate of the intake air flowing through the sub-passage 17 to the total passage (main passage 12 and sub-passage 17) in the low opening region. According to this result, by providing the directional protrusion 19, the flow rate ratio of the intake air flowing through the sub-passage 17 increases compared to the comparative example where the directional protrusion 19 is not provided. Specifically, in the region where the opening degree of the throttle valve 30 is 5 degrees to 15 degrees, it increases by about 50% to 10% compared to the comparative example. Thus, by providing the directional protrusion 19, a larger amount of intake air can be made to flow toward the sub-passage 17.

[0059] Furthermore, FIG. 14 shows the result of simulating the total flow rate of the intake air flowing through the total passage (main passage 12 and sub-passage 17) when the throttle valve 30 rotates from the fully closed state to the fully open state. According to this result, only a slight decrease in the flow rate occurs in the vicinity where the throttle valve 30 reaches the fully open region. That is, in the practical rotation region of the internal combustion engine, the influence of the directional protrusion 19 on the total flow rate is almost negligible. In other words, the directional protrusion 19 functions to direct the intake air toward the branch port 17a of the sub-passage 17 with almost no passage resistance generated, and can increase the flow rate of the intake air flowing through the sub-intake passage 17.

[0060] Next, the operation of the internal combustion engine E equipped with the intake system IS will be described. First, when the internal combustion engine E is in the idle operation region, the throttle valve 30 is in a closed valve state closing the main passage 12, and the intake air sucked from the air cleaner Ac flows through the main intake passage Ip1, the main passage (main intake passage) 12, bypasses the throttle valve 30 and flows through the bypass passage 14, then flows back into the downstream main passage (main intake passage) 12, and together with the fuel injected by the fuel injection valve Iv in the main intake passage Ip1, enters the combustion chamber C as an air-fuel mixture through the main intake passage Ip1 and the intake port (main intake passage) 3a. In this state, the adjustment valve 50 adjusts the passage area of the bypass passage 14 (communication passage) to maintain the idle operation of the internal combustion engine E in a stable state.

[0061] On the other hand, when the internal combustion engine E is in an operation region other than the idle operation region (low load to medium load to high load), the throttle valve 30 opens to open the main passage 12. Therefore, the intake air flowing through the main passage 12 is sucked into the combustion chamber C by flowing through the main passage 12 or the sub-passage 17 without passing through the bypass passage 14.

[0062] That is, in the low load to medium load operation region where the throttle valve 30 opens from the fully closed position to a predetermined opening degree θ, the opening area A of the branch port 17a communicating with the main passage 12 upstream of the first half body region 30a of the throttle valve 30 gradually increases as the throttle valve 30 rotates. Therefore, the intake air flowing from the main passage 12 upstream of the throttle valve 30 is guided to the first half body region 30b inclined toward the downstream side of the throttle valve 30 and directed to the branch port 17a and flows into the sub-passage 17, and the intake air flowing behind the second half body region 30b inclined toward the upstream side of the throttle valve 30 is directed toward the branch port 17a by the collision surface 19a of the pointing protrusion 19 and flows into the sub-passage 17. As a result, most of the intake air flowing from upstream of the throttle valve 30 flows into the sub-intake passage (sub-passage 17, sub-intake passage Sp1, sub-port 3b), and a swirl flow (lateral vortex) is generated in the air-fuel mixture flowing into the combustion chamber C. This swirl flow promotes the atomization of the fuel and the homogenization of the air-fuel mixture, improving the combustion efficiency.

[0063] And in a high-load operation region where the throttle valve 30 rotates from a predetermined opening degree θ to a fully open position, the opening area of the branch port 17 does not change, and the throttle valve 30 becomes parallel to the center line L1 of the main passage 12. Therefore, the intake air flowing through the main passage 12 is hardly directed toward the sub-passage 17 by the throttle valve 30, and flows downstream in the main passage 12. As a result, in the high-load operation region, the intake air amount flowing through the main intake passage (main intake passage Ip1, main passage 12, main intake passage Ip1, intake port 3a) increases, the combustion speed increases, and efficient combustion is promoted.

[0064] That is, as shown in FIG. 13, when the throttle valve 30 opens from the fully closed position toward the fully open position, in a low-load to medium-load operation region (a low opening degree region where the opening degree of the throttle valve 30 ranges from 0 degree to a predetermined opening degree θ), the ratio of the intake air flowing through the sub-intake passage (sub-passage 17, sub-intake passage Sp1, sub-port 3b) increases. Also, in a medium-load to high-load operation region (an opening degree region where the throttle valve 30 exceeds the predetermined opening degree θ), the ratio of the intake air flowing through the sub-intake passage (sub-passage 17, sub-intake passage Sp1, sub-port 3b) decreases, and the ratio of the intake air amount flowing through the main intake passage (main intake passage Ip1, main passage 12, main intake passage Ip1, intake port 3a) increases. Therefore, in a low-load to medium-load operation region, a swirl flow can be generated in the combustion chamber C to improve the combustion efficiency. Also, in a high-load operation region, the high-speed intake air flow mainly flowing through the main passage 12 increases, the combustion speed increases, and efficient combustion is promoted.

[0065] FIG. 15 shows another embodiment of the throttle device M of the present invention, which has the same configuration as the foregoing embodiment except that a sub-passage 117 and a direction projecting portion 119 are adopted instead of the sub-passage 17 and the direction projecting portion 19 in the foregoing embodiment. In this embodiment, the sub-passage 117 is formed such that its center line L2 forms a predetermined inclination angle β (for example, about 60 degrees) with respect to the center line L1 of the main passage 12 and extends obliquely downstream. Therefore, the branch port 117a of the sub-passage 117 opens so as to form an ellipse with respect to the main passage 12.

[0066] As shown in FIG. 15, the direction - projecting portion 119 projects from the inner wall surface 12a on the side facing the branch port 117a of the sub - passage 117 on the inner wall surface 12a that defines the main passage 12 on the downstream side of the axis S, and is formed to include a planar collision surface 119a against which the intake air flowing through the main passage 12 collides. And the direction - projecting portion 119 is configured to direct the intake air flowing through the main passage 12 toward the branch port 117a of the sub - passage 117 in a low - opening region from the state where the throttle valve 30 is closed to a predetermined opening θ. Also, similar to the aforementioned direction - projecting portion 19, the direction - projecting portion 119 projects from the inner wall surface 12a of the main passage 12 toward the center line L1 by a predetermined protruding amount and is formed to curve along the inner wall surface 12a. Also, as shown in FIG. 15, the collision surface 119a of the direction - projecting portion 119 is formed within the range of the intersection region Ca where the virtual passage Vp extending the sub - passage 117 into the main passage 12 intersects the main passage 12. Furthermore, the collision surface 19a of the direction - projecting portion 19 is formed to be directed and spread so as to be steeper than the inclination angle β of the center line L2 of the sub - passage 117.

[0067] FIGS. 16 to 20 show the results of simulating the intake air flow at each opening (5 degrees, 10 degrees, 15 degrees, 45 degrees, 85 degrees) from the state where the throttle valve 30 is closed to the fully - open position in this embodiment. According to this result, in the low - opening region (5 degrees to 15 degrees), the intake air actively flows into the sub - passage 17, and in the mid - opening and high - opening regions where the intake air flow into the sub - passage 17 is not required, the intake air flows through the main passage 12. According to this, in the low-load to medium-load operation range where the throttle valve 30 opens from the fully closed position to a predetermined opening θ, the flow rate of the intake air flowing through the sub-intake passage (sub-passage 17 and sub-intake passage Sp1) can be increased. As a result, a swirling flow such as a swirl flow can be generated in the combustion chamber C.

[0068] Also in this embodiment, similar to the previous embodiment, while achieving simplification of the structure, cost reduction, reduction of passage resistance, etc., the flow rate of the intake air flowing through the sub-intake passage can be increased. In particular, while reducing the passage resistance when flowing from the main passage 12 to the sub-passage 117, the intake air flowing through the main passage 12 can be efficiently guided to the sub-passage 117. As a result, a swirling flow such as a swirl flow can be generated in the combustion chamber C, contributing to the improvement of combustion efficiency.

[0069] In the intake system IS provided with the throttle device M according to the above embodiment, the confluence port 3b1 of the sub-intake passage (sub-port 3b) is shown to be oriented in a direction to generate a swirl flow in the combustion chamber C on the upstream side of the intake valve 4a. However, as shown in FIG. 21, the fuel injection valve Iv is arranged to directly inject fuel into the combustion chamber C, and the confluence port 113b1 of the sub-intake passage (sub-port 113b) may adopt a configuration that is oriented in a direction to generate a tumble flow (longitudinal vortex) in the combustion chamber C on the upstream side of the intake valve 4a.

[0070] As described above, according to the throttle device M of the present invention, a body 10 that defines a main passage 12 forming a part of the main intake passage and sub-passages 17 and 117 that branch from the main passage 12 and form a part of the sub-intake passage, and a throttle valve 30 that rotates around a predetermined axis S to open and close the main passage 12 and closes the main passage 12 on the upstream side of the branch ports 17a and 117a of the sub-passages 17 and 117. The body 10 includes directional protrusions 19 and 119 that protrude from the inner wall surface 12a that defines the main passage 12 so as to direct the intake air flowing through the main passage 12 toward the branch ports 17a and 117a in the low opening region from the state where the throttle valve 30 is closed to a predetermined opening θ. According to this, while achieving simplification of the structure, cost reduction, reduction of passage resistance, etc., in the low-load to medium-load operation region corresponding until reaching the predetermined opening θ, the flow rate of the intake air flowing through the sub-intake passages (17, Sp1, 3b) can be increased, and a swirling flow (swirl flow or tumble flow) can be actively generated in the combustion chamber C. As a result, the combustion efficiency of the internal combustion engine E can be improved.

[0071] In the above embodiment, as shown in FIG. 7, the branch port 17a of the sub-passage 17 was shown in the case where its upstream edge portion forms a right-angled cross section, but it is not limited to this. As shown in FIG. 22, a chamfer 17a1 forming a tapered surface (or curved surface) inclined toward the downstream side of the sub-passage 17 may be provided in the region of the upstream edge portion of the branch port 17a. According to this, when the intake air flows from the main passage 12 toward the sub-passage 17, separation of the flow can be suppressed or prevented in the upstream edge portion region of the branch port 17a, and the intake air amount flowing through the sub-passage 17 can be increased.

[0072] In the above embodiment, as the throttle valve, the throttle valve 30 in the form of a butterfly valve was shown, but it is not limited to this. As long as it is a throttle valve that opens and closes the main intake passage (main passage) and, in relation to the sub-intake passage (sub-passage), the branch port of the sub-passage is blocked from the main passage upstream of the throttle valve in the closed valve state, and the opening area communicating with the main passage upstream of the throttle valve increases according to the opening of the throttle valve until the throttle valve reaches a predetermined opening, any other form of throttle valve may be adopted.

[0073] In the above embodiment, as the bypass passage bypassing the throttle valve 30, the bypass passage 14 branching from the main passage 12 upstream of the throttle valve 30 and merging into the main passage 12 downstream of the throttle valve 30 was shown, but it is not limited to this. A bypass passage branching from the main passage 12 upstream of the throttle valve 30 and merging into the middle of the sub-passages 17, 117 may be adopted.

[0074] In the above-described embodiment, the main intake passage (main passage) and the sub-intake passage (sub-passage) have a circular cross-section, and the branch port of the sub-intake passage (sub-passage) is circular or elliptical. However, the present invention is not limited to this, and other forms of the main intake passage (main passage), the sub-intake passage (sub-passage), and the branch port may be adopted.

[0075] In the above-described embodiment, the downstream side of the sub-passage 17 is defined by the connector 17b and the connector 17b is connected to the sub-intake pipe Sp. However, the present invention is not limited to this, and the connector 17b may be abolished and the downstream connection portion 11b of the body 10 may be directly connected to the sub-intake passage formed in the main intake pipe Ip (intake manifold) to which the main intake pipe Ip is connected.

[0076] In the above-described embodiment, the vehicle equipped with the internal combustion engine to which the throttle device and the intake system of the present invention are applied is a motorcycle. However, the present invention is not limited to this, and it may be applied to an internal combustion engine mounted on an automobile or the like.

[0077] As described above, the throttle device and the intake system of the internal combustion engine of the present invention can achieve simplification of the structure, cost reduction, reduction of passage resistance, etc., and can increase the flow rate of the intake air flowing through the sub-intake passage. Therefore, swirling flows such as swirl flow and tumble flow can be generated in the combustion chamber, which contributes to the improvement of combustion efficiency. Therefore, it can be applied not only to an internal combustion engine mounted on a motorcycle or the like, but also to an internal combustion engine mounted on an automobile or an internal combustion engine mounted on other vehicles.

Explanation of Reference Numerals

[0078] E Internal combustion engine C Combustion chamber 3a Intake port (main intake passage) 3b, 113b Sub-port (sub-intake passage) 3b1, 113b1 Confluence port of sub-intake passages 4a Intake valve IS Intake system Ac Air cleaner Ip Intake pipe Ip1 Main intake passage Sp Sub-intake pipe (passage member) Sp1 Sub-intake passage Gp Gas pipe Gp1 Gas passage T Fuel tank Iv Fuel injection valve M Throttle device 10 Body 12 Main passage (main intake passage) 12a Inner wall surface L1 Center line of the main passage 14 Bypass passage 14a Upstream passage (bypass passage) 14b Downstream passage (bypass passage) 14b1 Junction of the bypass passage 14c Connecting passage (bypass passage) 16 Detection port 17, 117 Sub-passage (sub-intake passage) 17a, 117a Branch of the sub-passage 17b Connector (sub-passage) L2 Center line of the sub-passage 18 Purge passage 18a Inlet of the purge passage 18b Connector (purge passage) 19, 119 Pointing protrusion 19a, 119a Collision surface H Protrusion amount C, Cm Gap between the outer edge of the second half body region and the inner wall surface Vp Virtual passage Ca Intersection region 20 Rotation axis S Axis of the rotation axis 30 Throttle valve θ Predetermined opening degree A Opening area 30a First half body region 30b Second half body region L3 Center line of the throttle valve 50 Adjusting valve U Sensor unit 60 Angular position sensor 70 Pressure Sensor

Claims

1. A throttle device applied to an intake system of an internal combustion engine including a main intake passage that guides intake air into a combustion chamber and a sub-intake passage that branches off from a middle portion of the main intake passage and merges into the main intake passage in the vicinity of the combustion chamber, a body that defines a main passage forming a part of the main intake passage and a sub-passage that branches off from the main passage and forms a part of the sub-intake passage, and a throttle valve that rotates around a predetermined axis to open and close the main passage and closes the main passage upstream of a branch port of the sub-passage, comprising: the body includes a directional protrusion protruding from an inner wall surface that defines the main passage so as to direct intake air flowing through the main passage toward the branch port in a low opening region from a state where the throttle valve is closed to a predetermined opening degree, A throttle device characterized by the above.

2. The directional protrusion is formed on a side facing the branch port. The throttle device according to claim 1, characterized by the above.

3. The branch port is formed at a position where an opening area communicating with the main passage upstream of the throttle valve increases according to the opening degree of the throttle valve until the throttle valve reaches the predetermined opening degree, The directional protrusion is formed at a position facing the branch port downstream of the axis. The throttle device according to claim 1, characterized by the above.

4. The throttle valve includes a first half-body region and a second half-body region with the axis as a boundary. When the valve is opened, the first half-body region inclines toward the downstream side and faces the branch port side, and the second half-body region is formed to incline toward the upstream side, The directional protrusion is formed on a side facing the branch port. The throttle device according to claim 1, characterized by the above.

5. The main passage has a circular cross-section in a region where the throttle valve rotates, The directional protrusion protrudes from the inner wall surface by a predetermined protrusion amount and is formed to curve along the inner wall surface. The throttle device according to claim 4, characterized by the above.

6. The protrusion amount is formed to be smaller than a gap between an outer edge portion of the second half-body region and the inner wall surface when the throttle valve is at the predetermined opening degree on a plane perpendicular to the axis and including the center line of the main passage. The throttle device according to claim 5, characterized by the above.

7. The branch port is arranged such that its center is located on a plane including the center line of the main passage and the center line of the throttle valve perpendicular to the axis line. The throttle device according to claim 1, characterized in that.

8. The pointed protrusion is formed on the side facing the branch port and includes a planar collision surface against which the intake air flowing through the main passage collides. The collision surface is formed within the range of the intersection region where a virtual passage extending the sub-passage into the main passage intersects with the main passage. The throttle device according to claim 1, characterized in that.

9. The sub-passage is formed such that its center line extends perpendicular to the center line of the main passage. The collision surface is formed upstream of the center of the intersection region in the extending direction of the main passage. The throttle device according to claim 8, characterized in that.

10. The collision surface is oriented so as to expand perpendicular to the center line of the main passage. The throttle device according to claim 9, characterized in that.

11. The sub-passage is formed such that its center line extends downstream at a predetermined inclination angle with respect to the center line of the main passage. The throttle device according to claim 8, characterized in that.

12. The collision surface is oriented to be steeper than the inclination angle of the center line of the sub-passage. The throttle device according to claim 11, characterized in that.

13. The body includes a bypass passage that bypasses the throttle valve. The branch port is arranged at a position deviated from the confluence port of the bypass passage. The throttle device according to claim 1, characterized in that.

14. The body includes a detection port for detecting the pressure in the main passage downstream of the throttle valve. The branch port is arranged at a position deviated from the detection port. The throttle device according to claim 1, characterized in that.

15. The body includes a purge passage that forms a part of a gas passage for guiding fuel evaporation gas to the main intake passage. The inlet of the purge passage is located upstream of the throttle valve when the throttle valve is closed and is formed to be located immediately downstream of the throttle valve during the process of the throttle valve reaching the predetermined opening degree. The throttle device according to any one of claims 1 to 14, characterized in that.

16. A main intake pipe that defines a part of a main intake passage for guiding intake air into a combustion chamber of an internal combustion engine, a fuel injection valve that injects fuel into the main intake passage or into the combustion chamber, a sub-intake pipe that defines a part of a sub-intake passage that branches off from the middle of the main intake passage and merges into the main intake passage in the vicinity of the combustion chamber, a gas pipe that defines a part of a gas passage for guiding fuel evaporation gas in a fuel tank into the main intake passage, and a throttle device disposed in the middle of the main intake pipe, wherein the throttle device is the throttle device according to claim 15, characterizing an intake system of an internal combustion engine.

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