JP2009293579A - Intake device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain reduction of an intake air flow rate while reducing the pressure loss, in an intake device wherein a butterfly type tumble control valve 20 for generating a tumble flow in a combustion chamber 8 of an internal combustion engine is disposed in an intake passage 15. <P>SOLUTION: When the tumble control valve 20 is in a slant posture, an upstream side end is abutted to a lower surface side of the intake passage 15, and a downstream side end is opposed to an upper surface side of the intake passage 15 in a non-contact manner. An upstream side region (20a) of tilting fulcrums 21 and 22 of the tumble control valve 20 is a warp face so that intake air is easily introduced, and a downstream region (20b) of the tilting fulcrums of the tumble control valve 20 is an reverse warp face so that the intake air is easily delivered to the downstream side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an intake device in which a tumble control valve for generating a tumble flow in a combustion chamber of an internal combustion engine (engine) is provided in an intake passage.

  Generally, in an internal combustion engine mounted on a vehicle, the fuel efficiency of the internal combustion engine is improved by increasing the combustion efficiency of the fuel by setting the fuel at a low rotation speed to a lean state.

  Therefore, a technique is known that promotes vaporization and atomization of fuel in the combustion chamber by generating a vertical spiral flow, that is, a tumble flow, in the combustion chamber.

  In this technology, a tumble control valve is used, and this tumble control valve is classified into a cantilever type or a flap type and a butterfly type.

  First, the cantilever type or flap type tumble control valve is supported so that one end of the tumble control valve can tilt to the floor surface side of the intake passage, and the free end side is lowered or raised. ing. On the other hand, the butterfly-type tumble control valve is supported so that its middle in the longitudinal direction can be tilted in the middle of the intake passage in the up-and-down direction, so that it can be in a lateral orientation or an oblique orientation.

  Since the present invention is directed to a configuration using a butterfly type tumble control valve, a conventional example of a configuration including this butterfly type tumble control valve is presented (see, for example, Patent Document 1).

  In the conventional example shown in Patent Document 1, a so-called butterfly-type tumble control valve is tiltably provided at an intermediate position in the vertical direction of the intake passage, and the intake passage is fully opened by setting the tumble control valve to a horizontal posture. Or, the upper region of the intake passage is slightly opened in an oblique posture. In the latter case, a tumble flow is generated in the combustion chamber.

In this conventional example, in the tumble control valve, the upstream end of the intake direction is formed of an elastic material, and only the upstream end is pressed against the lower surface of the intake passage so that the upstream end is elastic. Or the upstream end is bent and the upstream end is bent when the upstream end is brought into pressure contact with the lower surface of the intake passage. It is configured to.
JP 2007-192094 A

  In the conventional example shown in Patent Document 1 described above, the purpose of bending or bending the upstream end portion of the tumble control valve is described as eliminating the need to provide a dead space on the lower surface side of the intake passage. This is fundamentally different from the following objective idea of the present invention.

  In addition, in the conventional example according to Patent Document 1, when the tumble control valve is in the lateral orientation and the intake passage is fully opened, or in the oblique orientation and the upper region of the intake passage is slightly opened, the pressure is increased. In order to reduce the loss (total pressure loss), there is no description that a fixed wall is provided at the front and rear positions of the tumble control valve, and such a technical idea cannot be heard.

  By the way, in the technique disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-257976, when the free end side of the cantilever type tumble control valve is tilted to the lower surface side of the intake passage, the entire tumble control valve is moved to the intake passage. It is described that it can be accommodated in a depressed portion provided on the lower surface side of the.

  Further, for example, in the technique disclosed in Japanese Patent Application Laid-Open No. 2006-283696, the entire tumble control valve is shaped to bulge upward as viewed from the side. However, in this technology, a partition plate is provided in the middle of the intake passage in the vertical direction, and both the upper and lower flow paths of the partition plate are opened by lowering the free end of the cantilever type tumble control valve. A half-open state in which the lower flow path of the partition plate is closed and only the upper flow path is opened by raising the free end side of the tumble control valve to be connected to the edge of the partition plate. It is supposed to be.

  In the case of using a cantilever type tumble control valve like these two prior arts, the tumble control valve is arranged in the middle in the vertical direction of the intake passage as in the case of using a butterfly type tumble control valve. Therefore, the problem that the pressure loss of the intake air becomes large and the intake air flow rate tends to decrease does not occur.

  As described above, since any of the above prior arts is different from the subject of the present invention and has no common problem, it should be recognized as a mere reference.

  The present invention can suppress a decrease in intake air flow rate while reducing pressure loss in an intake device in which a butterfly type tumble control valve for generating a tumble flow in a combustion chamber of an internal combustion engine is provided in an intake passage. The purpose is to.

  The present invention relates to an intake device in which a tumble control valve for generating a tumble flow in a combustion chamber of an internal combustion engine is provided in an intake passage, wherein the tumble control valve is tilted with a middle in the longitudinal direction as a fulcrum. When the type is in an inclined position, the upstream end contacts the lower surface of the intake passage, while the downstream end faces the upper surface of the intake passage in a non-contact manner. The region upstream from the tilting fulcrum of the tumble control valve is a warped surface that facilitates the intake air, and the region downstream from the tilting fulcrum of the tumble control valve is the intake air downstream. It is characterized by a reverse warping surface that facilitates feeding.

  In this configuration, when the tumble control valve is raised in an oblique position, the intake air flows toward the upper gap of the intake passage and flows into the combustion chamber in a biased state, and a strong tumble flow is generated in the combustion chamber. To occur.

  In this way, when the tumble control valve is inclined to generate a strong tumble flow, the intake air flows obliquely upward and is guided to the upper gap of the intake passage. If a warped surface is provided on the upstream side and a reverse warped surface is provided on the downstream side like a valve, the intake air is guided so as to flow smoothly without peeling along the outer surface of each surface.

  As a result, the air resistance is reduced as much as possible, and the pressure loss (total pressure loss) can be reduced. Therefore, the reduction in the flow rate of the intake air can be suppressed, and the tumble flow Can be strengthened.

  Note that the tumble strength can be arbitrarily adjusted by tuning the shape of the warped surface and the reverse warped surface and the gap.

  Preferably, the intake passage is provided with an upstream fixed wall that receives an upstream end portion and a downstream fixed wall that receives a downstream end portion in the tumble control valve in a horizontally oriented posture, and the lateral direction It can be set as the structure by which the joint of the both ends of the tumble control valve of an attitude | position and the said both fixed walls is made into the state connected smoothly, without protruding.

  According to this configuration, when the tumble control valve is set to the horizontal orientation, the tumble control valve, the upstream side fixed wall, and the downstream side fixed wall are connected to each other. In this state, the intake air is guided so as to flow smoothly without being separated along the outer surfaces of the three parties.

  In addition, since the joint is smoothly connected, the intake air is less likely to be disturbed or peeled off at the joint.

  As a result, the air resistance is reduced as much as possible, and the pressure loss can be reduced, so that the reduction in the flow rate of the intake air can be suppressed.

  Preferably, the upstream fixed wall has a blade shape that gradually becomes thin toward the upstream side of the intake passage, and the downstream side fixed wall has a blade shape that gradually becomes thin toward the downstream side of the intake passage. Can be configured.

  According to this configuration, the intake air is diverted with little resistance in the thin portion of the upstream fixed wall, and it is difficult for swirling to occur downstream of the thin portion of the downstream fixed wall. When the valve is in the horizontal orientation, the valve, upstream fixed wall, and downstream fixed wall are connected in a streamlined manner, reducing air pressure as much as possible and reducing pressure loss. Is possible.

  Preferably, the contact portion between the tumble control valve and the fixed wall may be provided with a concave portion and a convex portion that are fitted and fitted to each other.

  According to this configuration, the foreign matter mixed in the intake air flowing in the intake passage is caused by the upstream and downstream ends of the tumble control valve, the downstream portion of the upstream fixed wall, and the upstream side of the downstream fixed wall. Even if it comes to adhere to the part, when the tumble control valve is in the horizontal posture and its upstream end and downstream end are brought into contact with both fixed walls, Will be scraped off.

  In particular, in the case of an internal combustion engine equipped with an exhaust gas recirculation device called EGR, it is considered that oil components, soot and the like contained in the exhaust gas are likely to adhere as deposits. Can be removed.

  According to the present invention, in an intake device in which a butterfly type tumble control valve for generating a tumble flow in a combustion chamber of an internal combustion engine is provided in an intake passage, when the opening degree of the tumble control valve is reduced or in a fully opened state. In this case, the air resistance can be made as small as possible, and the flow of the intake air can be made smooth and fast. Therefore, it is possible to suppress a decrease in the intake air flow rate while reducing the pressure loss.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings.

  First, FIG. 1 to FIG. 7 show an embodiment of the present invention. Here, with reference to FIG. 1, schematic configurations of an internal combustion engine and an intake device to which the present invention is applied will be described.

  FIG. 1 is a schematic configuration diagram schematically showing a combustion chamber of an internal combustion engine and its periphery. In the figure, 1 is a cylinder block and 2 is a cylinder head.

  In this embodiment, in order to simplify the explanation and drawings, it is assumed that one intake valve 4 and one exhaust valve 5 are provided in one cylinder (cylinder) 1a as a model of the internal combustion engine. Needless to say, it is also possible to provide a four-valve multi-cylinder gasoline engine or the like in which two intake valves 4 and two exhaust valves 5 are provided in one cylinder 1a.

  A piston 6 is accommodated in the cylinder 1a of the cylinder block 1 so as to be capable of reciprocating in the vertical direction.

  The piston 6 is connected to a crankshaft (not shown) via a connecting rod 7, and the reciprocating motion of the piston 6 is converted by the connecting rod 7 into rotation of the crankshaft.

  A combustion chamber 8 is defined by the upper portion of the cylinder 1 a, the concave portion of the cylinder head 2, and the piston 6. A spark plug 9 is disposed at the upper portion of the combustion chamber 8.

  An intake port 11 and an exhaust port 12 formed in the cylinder head 2 are connected to the combustion chamber 8.

  An intake valve 4 is disposed at a communication portion between the intake port 11 and the combustion chamber 8, and an exhaust valve 5 is disposed at a communication portion between the exhaust port 12 and the combustion chamber 8. The intake valve 4 and the exhaust valve 5 are individually opened and closed by, for example, a camshaft (not shown).

  An intake pipe 14 including an intake manifold is connected to the intake port 11 of the cylinder head 2. An internal passage of the intake port 11 and the intake pipe 14 is an intake passage 15. Further, although not shown, an exhaust pipe including an exhaust manifold is connected to the exhaust port 12 of the cylinder head 2.

  The intake pipe 14 is provided with an electronically controlled throttle valve 16 for adjusting the intake air amount of the internal combustion engine. The throttle valve 16 is operated by a throttle motor 17. Although not shown, a surge tank is provided upstream of the throttle valve 16 in the intake pipe 14.

  Further, the cylinder head 2 is provided with an injector 18 for injecting fuel into the intake port 11. The injector 18 is supplied with fuel at a predetermined pressure from a fuel tank (not shown) by a fuel pump, and injects fuel into the intake port 11 as necessary.

  The fuel injected into the intake port 11 by the injector 18 is mixed with the air sucked into the intake passage 15 to become an air-fuel mixture, and is introduced into the combustion chamber 8 of the internal combustion engine. The air-fuel mixture introduced into the combustion chamber 8 is burned by ignition of the spark plug 9 after the compression stroke of the internal combustion engine.

  By the way, in this embodiment, in order to generate a tumble flow in the combustion chamber 8, a tumble control valve 20 for generating a tumble flow in the combustion chamber 8 is provided in the intake passage 15.

  The tumble control valve 20 is a so-called butterfly type, that is, is installed so as to tilt like a seesaw with the support shafts 21 and 22 provided in the middle in the longitudinal direction as fulcrums.

  Specifically, when the tumble control valve 20 is tilted in an oblique posture, the upstream end thereof is lowered and comes into contact with the lower surface (floor surface) of the intake passage 15 without any gap, while the downstream end is It rises and it will be in the state which opposes non-contact so that a suitable clearance gap may be made in the upper surface (ceiling surface) side of the intake passage 15.

  The tumble control valve 20 can be appropriately changed in posture by an actuator 23 such as an appropriate motor, and the opening degree is adjusted according to the posture. The actuator 23 is controlled by the following control device 24.

  The intake passage 15 is provided with fixed walls 26 and 27 for receiving the upstream end portion and the downstream end portion of the tumble control valve 20.

  The pair of fixed walls 26 and 27 are installed at a substantially central position in the vertical direction in a region that does not interfere with the fuel injection region by the injector 18 in the intake passage 15.

  Specifically, in this embodiment, the pair of fixed walls 26 and 27 are installed on the intake pipe 14 side of the intake pipe 14 and the intake port 11 constituting the intake passage 15.

  The pair of fixed walls 26 and 27 are integrated with the tumble control valve 20 to divide the intake passage 15 into two upper and lower flow paths when the tumble control valve 20 is set to the horizontal posture and fully opened. It is like that.

  Such a tumble control valve 20 is formed in a curved shape so as to wave when viewed from the side of a substantially oval plate-like member.

  Specifically, the upstream region 20a of the tumble control valve 20 from the support shafts 21 and 22 is a warped surface that is curved in a concave shape when viewed from the upstream side in the intake direction so that intake air can be easily received. Further, the downstream region 20b of the tumble control valve 20 with respect to the support shafts 21 and 22 is a reverse warped surface that is curved in a convex shape when viewed from the upstream side in the intake direction so that the intake air can be easily sent downstream. .

  Of the pair of fixed walls 26, 27, the upstream fixed wall 26 disposed on the upstream side is formed into a triangular wing shape as viewed from the side so as to gradually become thinner toward the upstream side of the intake passage 15. Has been. Further, the downstream side fixed wall 27 disposed on the downstream side is formed in a triangular wing shape as viewed from the side so as to gradually become thinner toward the downstream side of the intake passage 15.

  On the downstream side of the upstream fixed wall 26, a receiving piece 26a is provided for receiving the upper surface side of the upstream end when the tumble control valve 20 is set in the horizontal posture. On the other hand, on the upstream side of the downstream fixed wall 27, a receiving piece 27a is provided for receiving the lower surface side of the downstream end portion when the tumble control valve 20 is in the horizontal posture.

  The upstream side edge and the downstream side edge of the tumble control valve 20 are rounded in a convex shape when viewed from the plane, and the receiving piece of the upstream side fixing wall 26 corresponds to this shape. The inner sides of the receiving pieces 27a of the 26a and the downstream side fixed wall 27 are formed in a concave round shape.

  Further, the tumble control valve 20 is set to the horizontal posture, the upper surface side of the upstream end portion is the receiving piece 26a of the upstream fixing wall 26, and the lower surface side of the downstream end portion is the receiving piece 27a of the downstream fixing wall 27. In this state, the joint between the tumble control valve 20 and the two fixed walls 26 and 27 is in a state of smoothly connecting without protruding. This makes it difficult for turbulence and separation of the intake air to occur at the joint.

  Incidentally, in this embodiment, the control device 24 that controls the operation of the tumble control valve 20 as described above does not use an ECU dedicated to tumble flow control, but uses the ENG_ECU.

  Although not shown in detail, the control device 24 includes a CPU for performing control processing and arithmetic processing, a storage device for storing various programs and data (memory such as ROM, RAM, SRAM, and EEPROM), an input circuit, and an output circuit. Etc., and a computer having a known structure.

  This control device 24 uses signals from various sensors attached to the internal combustion engine (internal combustion engine parameters: signals corresponding to the operating state of the occupant and the operating state of the internal combustion engine) because of the use of the ENG_ECU as described above. Based on this, various controls relating to the operation of the internal combustion engine are performed.

  Various sensors for detecting the internal combustion engine parameters are not shown, but include a water temperature sensor, an air flow meter, an intake air temperature sensor, a throttle position sensor, a crank position sensor (engine speed sensor), a cam position sensor, Examples include an accelerator position sensor.

  The control device 24 controls the internal combustion engine by controlling an igniter (not shown) of the spark plug 9, a throttle motor 17 of the throttle valve 16, an injector 18, an actuator 23 of the tumble control valve 20, and the like.

  Next, the operation of the internal combustion engine will be briefly described.

  In the intake stroke of the internal combustion engine, normally, the air-fuel mixture is drawn into the combustion chamber 8 from the intake port 11 when the piston 6 is lowered while the intake valve 4 is open.

  Therefore, when the operating state of the internal combustion engine is, for example, a high-speed rotation range where the throttle valve 16 is fully opened, the intake passage 15 is fully opened by setting the tumble control valve 20 to a lateral orientation as shown in FIG. And

  In such a fully open state, the intake passage 15 is partitioned into two upper and lower stages by the tumble control valve 20 and the fixed walls 26 and 27, but the intake air flows through both the upper region and the lower region of the intake passage 15. As a result, the entire flow of the valve head of the intake valve 4 flows into the combustion chamber 8 almost uniformly, so that the amount of tumble flow generated in the combustion chamber 8 becomes small.

  On the other hand, when the operating state of the internal combustion engine is, for example, in the low-speed / medium-speed rotation range, the tumble control valve 20 is shown in FIG. 6 in order to generate a tumble flow in the combustion chamber 8 to improve the combustion state. Thus, the maximum closed state in which the upper portion of the intake passage 15 is slightly opened is obtained by raising the position in an oblique posture.

  Here, the maximum closed state refers to a state in which the tumble control valve 20 and the intake valve 4 are close to being fully closed but not fully closed. That is, in the case of the tumble control valve 20, as shown in FIG. 6, an appropriate gap exists between the upstream end and the intake passage 15, and in the case of the intake valve 4, for example, FIG. As shown, the idle opening state is set so as to ensure the idle speed.

  In such a maximum closed state, the intake air passes through a slight gap above the intake passage 15 and flows into a combustion chamber 8 from a partial region of the valve head outer periphery of the intake valve 4. A strong tumble flow is generated in the cylinder 8. Due to the generation of the tumble flow, the inside of the combustion chamber 8 is agitated and the vaporization of the fuel is promoted, so that the fuel combustibility in the combustion chamber 8 is improved.

  By the way, when the tumble control valve 20 is fully opened in the lateral orientation as described above, the tumble control valve 20, the upstream fixed wall 26, and the downstream fixed wall 27 are connected in a streamlined manner. Therefore, the intake air is guided to flow smoothly and quickly without peeling along the outer surfaces of the three parties. In addition, since the three joints are smoothly connected, the intake air is less likely to be disturbed or peeled off at the joints.

  In addition, when the tumble control valve 20 is in the obliquely maximally closed state as described above, intake air is received at the warped surface of the upstream region 20a of the tumble control valve 20 and sent to the reverse warped surface side of the downstream region 20b. In this case, the air is guided to the upper gap by the reversely warped surface, and at this time, the intake air is guided so as to flow smoothly and quickly without peeling along the outer surface of each surface.

  Further, the intake air is diverted with little resistance in the upstream thin wall portion of the upstream fixed wall 26, and vortex is less likely to occur downstream of the downstream thin wall portion of the downstream fixed wall 27.

  For these reasons, in any state, the air resistance in the intake passage 15 is reduced as much as possible, and the pressure loss can be reduced. Even with the control valve 20, it is possible to suppress a decrease in the flow rate of the intake air. In particular, when the tumble control valve 20 is inclined, the tumble flow can be strengthened as much as possible.

  In addition, this invention is not limited only to the said embodiment, All the deformation | transformation and application included in the range equivalent to the claim and the said range are possible. Examples are given below.

  (1) Another embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a perspective view of the tumble control valve, FIG. 9 is a plan view showing the tumble control valve, and FIG. 10 is a plan view showing a part of the tumble control valve and a fixed wall in an enlarged manner. .

  In this embodiment, the concave portions 28 and 29 and the convex portions 26b and 27b that are fitted and fitted to each other are provided at the contact portion between the tumble control valve 20 and the fixed walls 26 and 27.

  Specifically, concave portions 28 and 29 are provided in the upstream end portion and the downstream end portion of the tumble control valve 20, and the convex portions 26 b and 27 a in the receiving pieces 26 a and 27 a of both the fixing walls 26 and 27 are provided. 27b is provided. The concave portions 28 and 29 and the convex portions 26b and 27b are shaped to fit together.

  According to this configuration, foreign matter mixed in the intake air flowing in the intake passage 15 is caused by the concave portions 28 and 29 of the tumble control valve 20, the convex portion 26 b of the upstream fixed wall 26, and the convex portion 27 b of the downstream fixed wall 27. Even when the tumble control valve 20 is in the horizontal posture and the recesses 28, 29 and the protrusions 26b, 27b are fitted to each other, the recesses 28, 29 and the protrusions 26b, 27b The mating fit causes the deposits attached to them to be scraped off. Due to such a self-cleaning action, it is possible to avoid the occurrence of problems such as a decrease in the intensity of the tumble flow due to the accumulation of deposits.

  (2) For the internal combustion engine to which the intake device according to the above embodiment is applied, in addition to the configuration shown in FIG. 1, for example, although not shown, an exhaust gas recirculation device called EGR (Exhaust Gas Recirculation) is used. It can be a type provided.

  In short, the EGR is for returning exhaust gas to the intake system (for example, the intake passage 15) and reintroducing it into the combustion chamber 8 together with intake air for combustion.

  In this case, it is considered that oil components and soot contained in the exhaust gas returned to the intake system are likely to adhere as deposits to the tumble control valve 20 and the fixed walls 26 and 27. Even in such a case, as described in the above (1), if the concave portions 28 and 29 and the convex portions 26b and 27b are provided, the deposit can be easily removed by setting the tumble control valve 20 in the horizontal posture. This is preferable.

1 is a diagram schematically showing a schematic configuration in an embodiment of an intake device for an internal combustion engine according to the present invention. FIG. 2 is a perspective view schematically showing a tumble control valve and a pair of fixed walls in FIG. 1. It is the figure which expanded the tumble control valve of the fully open state shown in FIG. 1, and its periphery. FIG. 4 is a cross sectional view taken along line (4)-(4) in FIG. 3. FIG. 4 is a cross-sectional view taken along line (5)-(5) in FIG. 3. It is a figure which shows the state which made the tumble control valve the maximum closed in FIG. It is an arrow view of the (7)-(7) line cross section of FIG. FIG. 3 is a perspective view corresponding to FIG. 2 in another embodiment of the intake device for an internal combustion engine according to the present invention. FIG. 6 is a cross-sectional view corresponding to FIG. 5 in the embodiment of FIG. 8. It is a figure which expands and shows a part of tumble control valve and a downstream fixed wall planarly in embodiment of FIG.

Explanation of symbols

1 Cylinder block
1a cylinder
2 Cylinder head
4 Intake valve
8 Combustion chamber
11 Intake port (equivalent to part of the intake passage)
14 Intake pipe (corresponds to a part of the intake passage)
15 Intake passage
18 Injector
20 Tumble control valve 21, 22
23 Actuator
24 Control device
26 Upstream fixed wall
26a Receiving piece of upstream fixed wall
27 Downstream fixed wall
27a Receiving piece of downstream fixed wall

Claims (4)

An intake device in which a tumble control valve for generating a tumble flow in a combustion chamber of an internal combustion engine is provided in an intake passage,
The tumble control valve is a butterfly type that is tilted with the middle in the longitudinal direction as a fulcrum. When the tumble control valve is inclined, the upstream end abuts against the lower surface side of the intake passage, while the downstream end The portion is in a state of facing the non-contact on the upper surface side of the intake passage,
A region upstream from the tilting fulcrum of the tumble control valve is a warped surface that makes it easier to receive intake air, and a region downstream from the tilting fulcrum of the tumble control valve makes it easier to send intake air downstream. An air intake device characterized by being made into a slope. The intake device according to claim 1,
The intake passage is provided with an upstream fixed wall that receives an upstream end portion and a downstream fixed wall that receives a downstream end portion in a tumble control valve in a sideways posture,
In addition, the intake device is characterized in that the joint between the both end portions of the tumble control valve in the lateral orientation and the fixed walls is smoothly connected without protruding. The air intake device according to claim 2,
The upstream fixed wall has a blade shape that gradually becomes thinner toward the upstream side of the intake passage, and the downstream side fixed wall has a blade shape that gradually becomes thinner toward the downstream side of the intake passage. An air intake device characterized by that. The intake device according to claim 2 or 3,
An air intake apparatus according to claim 1, wherein a concave portion and a convex portion, which are fitted and fitted to each other, are provided at a contact portion between the tumble control valve and the fixed wall.

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