JP2004204820A - Throttling apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a throttling apparatus for preventing the rotation of a throttle valve from being disturbed by the freezing of waterdrops at a low temperature. <P>SOLUTION: A plurality of grooves 24 having a length in the axial direction of an air passage 21 are provided over the entire periphery of an air passage inner wall 22, and an annular projecting section 23 projecting coaxially with the air passage 21 from the air passage inner wall 22 into the air passage 21 is provided for adhering an inner periphery surface 23a of the projecting section 23 to an outer periphery surface 4a of a throttle valve 4 when the throttle valve 4 is at a fully closed position. As a result, the surface area of waterdrops adhering to the air passage inner wall 22 is expanded as compared with the case of the conventional throttle apparatus for evaporating quickly, and the arrival of waterdrops at the throttle valve 4 can be prevented by the projecting section 23, thus preventing the adhesion of waterdrops to the throttle valve 4 when it is cold for freezing and hence preventing the disturbance of the rotation. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a throttle device that adjusts a flow rate of air flowing through an air passage of an internal combustion engine (hereinafter, an “internal combustion engine” is referred to as an engine).
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in order to prevent air pollution due to engine exhaust, a part of the exhaust of the engine is recirculated in the middle of the intake passage of the engine and sucked into a cylinder, thereby lowering the combustion temperature and reducing the emission amount of NOx. That is, so-called EGR (exhaust gas recirculation) is performed.
[0003]
Engine exhaust contains water vapor generated during the combustion process. For this reason, when EGR is performed, water vapor in the exhaust is condensed on the inner wall of the air passage of the throttle body, and particularly in cold weather, the condensed water droplets may freeze and hinder the rotation of the throttle valve.
[0004]
In order to prevent freezing of water droplets on the inner wall of the air passage of the throttle body, it is known that an engine cooling water passage is provided in the throttle body near the throttle valve to flow cooling water, and the throttle body is heated by heat of the cooling water. I have. (For example, see Patent Document 1).
[0005]
Further, in another throttle device, in the above-mentioned EGR, an EGR valve for adjusting an exhaust flow rate to be recirculated to an intake passage is arranged close to a throttle body, and the throttle body is heated by exhaust heat, whereby an intake air is cooled. There is disclosed a technique for preventing the contained moisture from freezing on the inner wall of the throttle body.
[0006]
[Patent Document 1]
JP-A-8-14108
[Problems to be solved by the invention]
However, in the throttle device in which the cooling water passage is formed in the throttle body, there is a problem that the physical size is naturally increased because the cooling water passage is added to the throttle body.
[0008]
Further, the throttle device disclosed in Japanese Patent Application Laid-Open No. 8-14108 has a problem that it is necessary to improve the heat resistance of the throttle device since it is disposed close to the high temperature EGR valve, resulting in an increase in cost.
[0009]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a throttle device which can prevent rotation of a throttle valve from being hindered by freezing of water droplets at a low temperature.
[0010]
[Means for Solving the Problems]
The present invention employs the following technical means to achieve the above object.
[0011]
The throttle device according to the first aspect of the present invention includes a rotatable throttle shaft, a throttle valve fixed to the throttle shaft, and an air passage, and adjusts an air flow rate in the air passage in cooperation with the throttle valve. And a groove having a length in the axial direction of the air passage except for a portion in close contact with the outer peripheral surface of the throttle valve when the throttle valve is in the fully closed position on the inner wall of the air passage. I have.
[0012]
Here, when a water droplet adheres to the surface of a uniform planar object, the water droplet stops at a state where the surface tension and the weight of the water droplet are balanced (area and thickness). On the other hand, if a water droplet having the same volume as the above-mentioned water droplet adheres to an object having irregularities, for example, a groove, the surface tension is broken at the corner of the groove, and the area where the water droplet spreads adheres to the above-mentioned uniform plane. It will increase significantly than if you did.
[0013]
Therefore, when water droplets adhere to the inner wall of the air passage of the throttle device according to claim 1 of the present invention, i.e., the surface on which the groove is provided, the surface area of the throttle device is the same as the conventional throttle in which the inner wall of the air passage is a uniform cylindrical surface. It becomes much wider than when it adheres to the inner wall of the air passage of the device, that is, a uniform cylindrical surface without grooves. The larger the surface area, the greater the amount of water evaporated per unit time. As a result, it is possible to promote the evaporation of water droplets and evaporate them in a short period of time, and to suppress the water droplets from staying near the throttle valve, thereby preventing rotation of the throttle valve from being hindered by freezing of water droplets at low temperatures. Can be. Further, since the thickness of the water film becomes thinner as the surface area increases, even if water droplets freeze near the throttle valve, they can be separated with a small force.
[0014]
In addition, since the water droplets attached to the inner wall of the air passage can be widely diffused by the capillary action of the groove, the surface area of the water droplets can be more effectively enlarged.
[0015]
When the throttle valve on the inner wall of the air passage is in the fully closed position, no groove is formed in a portion in close contact with the outer peripheral surface of the throttle valve. Sex can be maintained.
[0016]
In addition, by adopting an easy means of providing a groove having a length in the axial direction of the air passage on the inner wall of the air passage, freezing at a low temperature can be performed without increasing the size and cost of the throttle device. A throttle device capable of preventing the rotation of the throttle valve from being hindered can be realized.
[0017]
A throttle device according to a second aspect of the present invention includes a rotatable throttle shaft, a throttle valve fixed to the throttle shaft, and an air passage, and adjusts an air flow rate in the air passage in cooperation with the throttle valve. A cylindrical throttle body, and a protruding portion provided in the air passage from the inner wall of the air passage so as to be coaxial with the air passage and annularly protruding, and the inner peripheral surface of the protruding portion has the throttle valve in a fully closed position. Sometimes, it is formed so as to be in close contact with the outer peripheral surface of the throttle valve. In this case, the surface in close contact with the outer peripheral surface of the throttle valve when the throttle valve is in the fully closed position is not formed as the inner wall of the air passage unlike the conventional throttle device, but instead of the protruding portion projecting from the inner wall of the air passage into the air passage. It has a peripheral surface. Thus, even if water droplets adhering to the inner wall of the air passage move toward the throttle valve due to airflow or vibration, it is possible to prevent the water droplets from adhering to the throttle valve by the protrusion. Therefore, it is possible to realize a throttle device that can prevent the rotation of the throttle valve from being hindered by icing at low temperatures.
[0018]
The throttle device according to a third aspect of the present invention has a configuration in which an annular concave or convex portion is provided concentrically with the air passage on the axial end surface of the air passage of the protruding portion. Thereby, an annular space is formed in the protruding portion. If water droplets adhering to the inner wall of the air passage move toward the throttle valve by air flow or vibration and reach the protruding portion, the water droplets are collected and stored in the above-mentioned space and do not reach the throttle valve. Adhesion to the throttle valve can be reliably prevented. In this case, if a groove having a length in the axial direction of the air passage is provided on the inner wall of the air passage except for the protruding portion, as in the throttle device according to the fourth embodiment of the present invention, the first embodiment will be described. In combination with the effect of the groove in the present invention, it is possible to realize a throttle device that can reliably prevent the rotation of the throttle valve from being hindered by icing at low temperatures.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a plurality of embodiments of a throttle device according to the present invention will be described with reference to the drawings.
[0020]
(1st Embodiment)
FIG. 1 is a sectional view of a throttle device 1 according to a first embodiment of the present invention. FIG. 2 is a sectional view of the throttle body 2 according to the first embodiment of the present invention, and is a sectional view taken along line II-II in FIG. FIG. 1 shows a fully closed position of the throttle valve 4.
[0021]
The throttle device 1 is mounted in the middle of an intake pipe (not shown) of an engine (not shown). The throttle device 1 is roughly rotatable with respect to the throttle body 2 having an air passage 21 formed therein. A throttle shaft 3 is supported and a throttle valve 4 is supported by the throttle shaft and rotates integrally with the throttle shaft.
[0022]
Further, in the throttle device 1, the airflow sucked into the engine flows in the direction indicated by the arrow in FIG.
[0023]
The throttle device 1 changes the effective cross-sectional area of the air passage 21 by rotating a throttle valve 4 installed in the air passage 21 of the throttle body 2 about the throttle shaft 3 so that the air flow rate passing through the air passage 21 is changed. That is, it adjusts the intake air flow rate of the engine.
[0024]
The throttle body 2 is formed in a substantially cylindrical shape from, for example, an aluminum alloy or a resin, and has an air passage 21 formed therein. The throttle body 2 rotatably holds a throttle shaft 3 described later. A protrusion 23 is provided on the inner wall 22 of the air passage of the throttle body 2 so as to project from the inner wall 22 of the air passage into the air passage 21. As shown in FIG. 1, the protrusion 23 is formed coaxially with the air passage 21 and in an annular shape. The inner peripheral surface 23a of the protruding portion 23 is formed so as to be in close contact with the outer peripheral surface 4a of the throttle valve 4 when the throttle valve 4 is at the fully closed position, that is, at the position shown in FIG. A plurality of grooves 24 having a length in the axial direction of the air passage 21 (the left-right direction in FIG. 1) are formed on the inner wall 22 of the air passage except for the protrusion 23 described above. As shown in FIG. 2, the grooves 24 are arranged at equal angular intervals on the entire circumference of the air passage inner wall 21. As shown in FIG. 1, one end of the groove 24 opens to the end face 23 b of the protruding portion 23, and the other end opens to the end face 2 a of the throttle body 2.
[0025]
The throttle valve 4 is made of metal, for example, brass, aluminum or the like, or resin, is fixed to the throttle shaft 3, and rotates integrally with the throttle shaft 3 in the air passage 21. In the fully closed position of the throttle valve 4, that is, the position shown in FIG. 1, the outer peripheral surface 4 a of the throttle valve 4 is in close contact with the inner peripheral surface 23 a of the protruding portion 23 of the throttle body 2 to cut off the communication with the air passage 21. I do.
[0026]
The throttle shaft 3 is made of metal, resin, or the like, and holds a throttle valve 4. Although the throttle shaft 3 and the throttle valve 4 are assembled after being manufactured as separate parts, they may be integrally formed of resin or the like.
[0027]
The throttle shaft 3 is engaged with one end of an accelerator cable (not shown) outside the throttle body 2. The other end of the accelerator cable is engaged with an accelerator pedal (not shown) in the driver's seat, and when the accelerator pedal is depressed by the driver, the throttle shaft 3 is linked to the opening direction of the throttle valve 4 (FIG. 1). , The air flow passing through the air passage 21, that is, the air flow sucked into the engine is adjusted.
[0028]
A return spring (not shown) is engaged with the throttle shaft 3, and is urged in the valve closing direction (counterclockwise at the head) by the elastic force of the return spring. Therefore, when the driver releases his / her foot from the accelerator pedal, or when the engagement between the accelerator pedal and the throttle shaft 3 is opened for some reason, the throttle valve 4 is rotated to the fully closed position, that is, the position shown in FIG. Move and stop.
[0029]
Next, the operation and effect of the configuration of the throttle body 2, which is a feature of the present invention, will be described.
[0030]
Generally, in an engine, so-called EGR (exhaust gas recirculation) is implemented in which a part of the exhaust gas of the engine is recirculated in the middle of the intake passage of the engine in order to reduce the emission amount of NOx in the exhaust gas of the engine. The engine exhaust contains water vapor generated during the combustion process. This water vapor may condense on the inner wall of the air passage of the throttle device. Particularly in cold weather, dew condensation may freeze and hinder the rotation of the throttle valve.
[0031]
In addition, a water droplet attached to the surface of a uniform planar object stops at a state where the surface tension and the weight of the water droplet are balanced (area and thickness).
[0032]
In the throttle device 1 according to the first embodiment of the present invention, a plurality of grooves 24 having a length in the axial direction of the air passage 21 (the left-right direction in FIG. 1) are formed in the inner wall 22 of the air passage. When the water droplet adheres to the inner wall 22 of the air passage, the surface tension of the water droplet is broken by the corner 24a of the groove 24. Therefore, the water droplet has a larger area and a smaller thickness than the case where the water droplet adheres to the above-mentioned uniform flat surface, and stops. At this time, the water droplet is further diffused along the groove 24 by the capillary action of the groove 24, and the surface area is enlarged. As a result, water droplets can be prevented from evaporating in a shorter time and staying in the vicinity of the throttle valve 4, so that it is possible to prevent water droplets from adhering to the throttle valve 4 in cold weather and freezing to hinder the rotation. Can be.
[0033]
Further, in the throttle device 1 according to the first embodiment of the present invention, an annular protrusion 23 is provided in the air passage 21 from the air passage inner wall 22 so as to project coaxially with the air passage 21, and the inner periphery of the protrusion 23 is provided. The surface 23a is formed so as to be in close contact with the outer peripheral surface 4a of the throttle valve 4 when the throttle valve 4 is at the fully closed position. Thus, when the throttle valve 4 is in the fully closed position, the contact portion between the throttle valve 4 and the throttle body 2 is not made flush with the inner wall of the air passage in the conventional throttle device, but instead from the inner wall 22 of the air passage to the inside of the air passage 21. The inner peripheral surface 23a of the protruding portion 23 protruding from the inner surface 23a. Thus, even if water droplets adhering to the inner wall 22 of the air passage move toward the throttle valve 4 due to airflow or vibration of the engine, they are blocked by the protrusion 23 and are prevented from adhering to the throttle valve 4. . Therefore, it is possible to prevent water droplets from adhering to the throttle valve 4 during freezing and freezing to prevent the rotation thereof.
[0034]
In the throttle device 1 according to the first embodiment of the present invention described above, the cross-sectional shape of the groove 24 is substantially rectangular as shown in FIG. 2, but need not be limited to a rectangle, but may be other shapes. There may be. For example, it may be trapezoidal as in a modification of the throttle device 1 according to the first embodiment of the present invention shown in FIG. Alternatively, a triangular shape may be used as in another modification of the throttle device 1 according to the first embodiment of the present invention shown in FIG. Further, as in another modified example of the throttle device 1 according to the first embodiment of the present invention shown in FIG. 4, the inner wall 22 of the air passage and the groove 24 may have a continuous curved shape.
[0035]
(2nd Embodiment)
FIG. 6 is a partial sectional view of the throttle device 1 according to the second embodiment of the present invention.
[0036]
The throttle device 1 according to the second embodiment of the present invention is different from the throttle device 1 according to the first embodiment of the present invention in that an annular groove which is concentric with the air passage 21 and is an annular concave portion is formed on the end face 23 b of the protrusion 23. 23c is added. With this configuration, an annular space is formed on the end surface 23b of the protrusion 23. When water droplets adhering to the inner wall 22 of the air passage move toward the throttle valve 4 due to airflow or vibration of the engine and reach the projecting portion 23, the water droplets are removed from the throttle device 1 according to the first embodiment of the present invention. In the same manner as in the above case, it is blocked by the protrusion 23 and is collected and stored in an annular groove 23c provided on the end face 23b of the protrusion 23. As a result, more water droplets can be collected and stored in the protruding portion 23, that is, the annular groove 23c, as compared with the case of the throttle device 1 according to the above-described first embodiment of the present invention. Adhesion to the valve 4 can be reliably prevented.
[0037]
(Third embodiment)
FIG. 7 is a partial sectional view of the throttle device 1 according to the third embodiment of the present invention.
[0038]
The throttle device 1 according to the third embodiment of the present invention is different from the throttle device 1 according to the first embodiment of the present invention in that the protrusion 23 is eliminated. In the throttle device 1 according to the third embodiment of the present invention, when the throttle valve 4 is fully closed, the groove 24 provided on the inner wall 22 of the air passage of the throttle body 2, as shown in FIG. The gap C is provided between the end and the throttle valve 4. The length of the gap C is set so that, for example, even when the opening of the throttle valve 4 is small, the flow rate of the air flowing through the air passage 21 does not become unstable. Also in the throttle device 1 according to the third embodiment of the present invention, the area of the water droplets attached to the air passage inner wall 22 is widened and thinned, and the water droplets evaporate in a shorter time and stay near the throttle valve 4. Therefore, it is possible to prevent water droplets from adhering to the throttle valve 4 during cold weather and freezing to prevent the rotation thereof.
[0039]
In the above-described throttle device 1 according to the first and second embodiments of the present invention, the groove 24 may be omitted. Also in this case, even if water droplets adhering to the inner wall 22 of the air passage move toward the throttle valve 4 due to airflow or vibration of the engine, the water droplets are blocked by the protrusion 23 or the protrusion 23 and the annular groove 23c. The sticking to the throttle valve 4 is prevented. Therefore, it is possible to prevent water droplets from adhering to the throttle valve 4 during freezing and freezing to prevent the rotation thereof.
[Brief description of the drawings]
FIG. 1 is a sectional view of a throttle device 1 according to a first embodiment of the present invention.
FIG. 2 is a sectional view of the throttle device 1 according to the first embodiment of the present invention, which is a sectional view taken along line II-II in FIG.
FIG. 3 is a partial sectional view of a modification of the throttle device 1 according to the first embodiment of the present invention.
FIG. 4 is a partial sectional view of another modification of the throttle device 1 according to the first embodiment of the present invention.
FIG. 5 is a partial sectional view of another modification of the throttle device 1 according to the first embodiment of the present invention.
FIG. 6 is a partial sectional view of a throttle device 1 according to a second embodiment of the present invention.
FIG. 7 is a partial sectional view of a throttle device 1 according to a third embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Throttle device 2 Throttle body 2a End surface 21 Air passage 22 Air passage inner wall 23 Projecting portion 23a Inner peripheral surface 23b End surface 23c Annular groove (recess)
24 groove 3 throttle shaft 4 throttle valve 4a outer peripheral surface C gap

Claims (4)

A rotatable throttle shaft,
A throttle valve fixed to the throttle shaft;
A cylindrical throttle body having an air passage and adjusting an air flow rate in the air passage in cooperation with the throttle valve,
A throttle device, wherein a groove having a length in the axial direction of the air passage is provided on an inner wall of the air passage except for a portion which is in close contact with an outer peripheral surface of the throttle valve when the throttle valve is in a fully closed position. A rotatable throttle shaft,
A throttle valve fixed to the throttle shaft;
A cylindrical throttle body having an air passage and adjusting an air flow rate in the air passage in cooperation with the throttle valve;
A protruding portion provided coaxially and annularly with the air passage in the air passage from the inner wall of the air passage,
The throttle device according to claim 1, wherein an inner peripheral surface of the protruding portion is formed to be in close contact with an outer peripheral surface of the throttle valve when the throttle valve is at a fully closed position. The throttle device according to claim 2, wherein an annular concave or convex portion is provided concentrically with the air passage on an axial end surface of the air passage of the protruding portion. 4. The throttle device according to claim 2, wherein a groove having a length in an axial direction of the air passage is provided on an inner wall of the air passage except for the protruding portion. 5.

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