JPH0749784B2 - Throttle assembly - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throttle valve assembly, and more particularly to a fuel injection device capable of ensuring a suitable throttle valve operation even when the outside air condition such as engine heat changes. The present invention relates to a throttle valve assembly.

[Conventional technology]

Generally, the intake cylinder body of the throttle valve assembly is made of an aluminum-based material, and the throttle valve shaft is made of an iron-based material. Therefore, if the throttle valve assembly is installed near the engine, when the engine is heated, a difference in the thermal expansion amount occurs due to the difference in the coefficient of thermal expansion between the material of the intake cylinder wall and the throttle valve shaft, and the throttle valve Is invaded by the intake cylinder wall surface. In order to prevent this problem, in Japanese Utility Model Laid-Open No. 61-137858, the throttle valve is formed in an elliptical shape with the major axis in the direction perpendicular to the throttle shaft and the minor axis in the valve axis direction. It has been proposed to form a gap between the valve end edge and the inner wall of the intake cylinder and absorb the difference in the amount of thermal expansion due to the difference in the coefficient of thermal expansion between the intake cylinder wall and the throttle shaft in the gap.

[Problems to be solved and used by the invention]

In recent years, it has been desired to reduce the idle speed of the engine as much as possible to reduce fuel consumption and noise during idling.
In order to satisfy this, the gap between the outer periphery of the throttle valve and the inner wall of the intake cylinder is made as small as possible, and the amount of air flowing between the outer periphery of the throttle valve and the inner wall of the intake cylinder is reduced during idle operation. Therefore, conventionally, it was not necessary to consider the influence of heat on the throttle valve assembly, but in the structure in which the gap between the outer periphery of the throttle valve and the inner wall of the intake cylinder becomes small, it becomes necessary to consider the influence of heat.

That is, in the past, there was no requirement to reduce the idle speed of the engine, so the gap between the outer circumference of the throttle valve and the inner wall of the intake cylinder was relatively large, about 80 to 100 μm. However, in order to reduce the idle speed, it is necessary to make the gap about 10 to 30μ.If this gap is made small, the heat of the engine causes the intake cylinder wall of the throttle valve assembly and the throttle shaft to move. Thermal expansion, and the gap becomes smaller due to the difference in the amount of thermal expansion resulting from the difference in the coefficient of thermal expansion due to the difference between the two materials,
In the worst case, a part of the inner wall of the intake cylinder interferes with a part of the outer circumference of the throttle valve, and vibration of the engine is added to this, and the interference part is worn away and partly turned up. The phenomenon of sticking to the inner wall occurs.

In the prior art described in Japanese Utility Model Laid-Open No. 61-137858, the problem is solved by forming the throttle valve into an elliptical shape. However, even if the throttle valve is formed in an elliptical shape, it is impossible to secure the above-mentioned minute gap in the entire outer circumference of the throttle valve during idle operation after engine heating. In addition, even if it can be done, high-precision machining is required.If the machining precision is a little poor, the gap between the outer diameter part of the throttle valve and the inner wall of the intake cylinder will increase during idle operation, reducing the air volume and reducing idle speed. The intended purpose of lowering cannot be achieved.

An object of the present invention is to reduce the idle speed of the engine so that when the gap between the inner wall of the intake cylinder and the outer periphery of the throttle valve is reduced, the minute gap is maintained even during idle operation and the inner wall of the intake cylinder is affected by heat. An object of the present invention is to provide a throttle valve assembly that can avoid interference with the outer circumference of the throttle valve.

[Means for Solving the Problems]

The above-mentioned object has a throttle valve shaft that is inserted substantially across the center of the intake cylinder, and a throttle valve that is fixed to the throttle valve shaft and that is disposed inside the intake cylinder. The intake cylinder is made of an aluminum-based material. In the made throttle valve assembly, the throttle valve shaft is made of a material whose main coefficient is aluminum whose thermal expansion coefficient is substantially the same as that of the material of the intake cylinder, and an oxide film is formed on the surface of the material whose main ingredient is aluminum. It is achieved by forming or converting the surface layer of the material into porous hard aluminum oxide, impregnating the porous structure with a tetrafluoride resin and surface strengthening.

Further, the above object is to provide a throttle valve assembly having a throttle valve shaft which is inserted across substantially the center of an intake cylinder, and a throttle valve which is fixed to the throttle valve shaft and is disposed in the intake cylinder. The valve shaft is made of a material having a coefficient of thermal expansion substantially the same as that of the material of the intake cylinder, one side of the throttle valve shaft is fixed to a bearing to prevent axial displacement of the throttle valve shaft, and the other side is loosely fitted to the bearing. To be achieved.

[Action]

By making the throttle shaft from a material whose main coefficient of thermal expansion is aluminum whose thermal expansion coefficient is almost the same as the material of the intake cylinder, the amount of thermal expansion of the throttle shaft and intake cylinder wall is reduced, and the interference between them is prevented. To be done. Further, since the outer peripheral shape of the throttle valve may be a circular shape as in the conventional case, variations in the gap due to machining errors do not occur, and a minute gap is maintained even during idle operation. In this case, since the aluminum material has a softer surface hardness than the conventional iron-based material, the surface strength and rigidity are improved and the durability is improved by forming an oxide film or impregnating the surface with a fluororesin. Reserved.

In addition, the throttle valve shaft is made of a material whose main component is aluminum. By fixing one side of the throttle valve shaft to the bearing and loosely fitting the other side to the bearing, the heat of the throttle valve shaft and the intake cylinder wall is It is possible to prevent interference due to the difference in expansion amount, and moreover, reliably restrain the axial movement of the throttle valve shaft against vibration of the engine, so that even when the engine speed is increased, biting of the throttle valve due to vibration can be avoided.

〔Example〕

 Preferred embodiments of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, reference numeral 20 denotes a throttle valve assembly, and the throttle valve assembly 20 includes an intake cylinder 2, a throttle valve 3 incorporated in an inner wall 2a of the intake cylinder 2, and a screw for fixing the throttle valve 3. Throttle shaft fixed by 4
It consists of 21 and. The throttle valve shaft 21 is inserted across substantially the center of the intake cylinder 2.

A throttle lever 8 is connected to one end of the throttle valve shaft 21, a return spring 10 is bonded between a pair of sleeves 9 close to the end portion thereof, and the throttle lever 8 is connected to the other end of the throttle valve shaft 21. A valve opening sensor 11 is attached. When the driver steps on the accelerator pedal (not shown), the throttle lever 8 moves, the throttle valve shaft 21 also moves simultaneously, and the throttle valve opens. When the accelerator pedal is released, the throttle valve is closed by the reaction force of the spring 10.

The gap between the outer periphery 3a of the throttle valve 3 and the intake cylinder inner wall 2a is, for example, 10 to 10 in order to reduce the amount of air during idle operation as much as possible, reduce the idle speed of the engine, and reduce fuel consumption and noise during idle. It is considered to be a minute gap of about 30μ.
However, this is a clearance that allows smooth movement when the throttle valve 3 is operated. In the figure, this gap is exaggerated for easy understanding.

By the way, as described above, when the throttle valve assembly 1 is thermally deformed by the heat of the engine or the like, the difference between the thermal expansion coefficients of the intake cylinder 2 and the throttle shaft 21 causes a difference between the intake cylinder inner wall 2a and the throttle outer circumference 3a. There is a phenomenon that the gap is partially narrowed and the throttle valve 3 bites into the air cylinder inner wall 2a. This phenomenon is most likely to occur when the throttle valve 3 is closed as shown in FIG. 1, that is, during idling operation. Therefore, in order to eliminate this phenomenon,
The throttle shaft 21 is made of a material having substantially the same thermal expansion coefficient as the material of the intake cylinder 2. Specifically, the intake cylinder 2 is made of an aluminum-based material, and the throttle valve shaft 21 is also made of a material whose main component is aluminum.

By doing so, the thermal expansion amounts of the intake cylinder 2 and the throttle valve shaft 21 become substantially the same, the uniformity of the gap between the throttle valve outer periphery 3a and the intake cylinder inner wall 2a can be maintained, and the interference between them can be avoided. can do. Further, since the outer peripheral shape of the throttle valve 3 may be circular as in the conventional case, variation in the gap due to processing error does not occur,
A minute gap can be maintained during idle operation to minimize the amount of air.

In addition, the aluminum material is weak in strength and the surface of the material is soft, so that the durability is often poor. To prevent this,
An oxide film is formed on the throttle valve shaft 21 by surface treatment to strengthen the surface. Instead of the oxide film, the surface layer of the material may be converted into porous hard aluminum oxide and the porous structure may be impregnated with tetrafluoride resin. As a result, surface strength and rigidity are improved, durability is ensured, wear resistance is improved, and reliability during use is improved.

The above is an embodiment in the case where the throttle valve assembly has one throttle valve, but it goes without saying that the present invention can be applied to a throttle valve assembly having a plurality of throttle valves. FIG. 3 shows an embodiment of a throttle valve assembly having two throttle valves. In the figure, the same or equivalent members as those shown in FIG. 1 are designated by the same reference numerals. This throttle assembly
Also in 25, similarly to the above embodiment, the throttle valve 21 is made of a material containing aluminum as a main component, and an oxide film is formed on the throttle valve 21 by a surface treatment, or the surface layer of the material is made of porous hard oxide. It is converted to aluminum and its porous structure is impregnated with tetrafluoride resin. As a result, as in the first embodiment, it is possible to avoid the interference due to thermal deformation while minimizing the amount of air leaking from the gap during idle operation.

Further, in the above embodiment, the throttle valve shaft 21 is not supported by a special bearing, but the throttle valve shaft 21 can be supported by a ball bearing fixed on one side. FIG. 4 shows such an embodiment, in which the throttle valve shaft 21 has a pair of ball bearings 6.
It is rotatably supported by a and 6b. In the ball bearings 6a and 6b, the inner race of one of the bearings 6a is tightly fitted to the throttle valve shaft 21 to fix one side of the throttle valve shaft 21, and the inner race of the other bearing 6b is loosely fitted to the throttle valve shaft 21. It is possible to move the throttle shaft 21 in the axial direction.

According to this embodiment, by installing the fixed bearing 6a,
A structure that is strong against vibration is provided, and even when the engine speed is increased, it is possible to avoid biting of the throttle valve due to vibration.

〔The invention's effect〕

According to the present invention, the influence of heat can be avoided only by devising the material of the throttle valve shaft, so that it is possible to prevent the interference due to thermal deformation while maintaining the minute gap and minimizing the air amount even during the idle operation. . For this reason, the operation of the throttle valve becomes smooth, and it is possible to prevent the throttle valve from biting into the intake cylinder inner wall or the defective return, and it is possible to improve the reliability of the throttle valve assembly.

Further, according to the present invention, it is possible to avoid biting of the throttle valve due to vibration.

[Brief description of drawings]

1 is a partial sectional top view showing a throttle valve assembly according to an embodiment of the present invention, FIG. 2 is a sectional view of the throttle valve assembly shown in FIG. 1, and FIG. FIG. 4 is a partial cross-sectional top view of a throttle valve assembly according to an embodiment, and FIG. 4 is a partial cross-sectional top view of a throttle valve assembly according to still another embodiment. Description of symbols 20,25,30 …… Throttle valve assembly 2 …… Intake cylinder 3 …… Throttle valve 3a …… Throttle valve outer circumference 21 …… Throttle valve shaft 6a …… Ball bearing 12a, 12b …… for one side fixing Recess (thermal expansion absorption means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-26330 (JP, A) Actually open 61-137858 (JP, U) Actually open 1-118137 (JP, U) Actually open 56- 90430 (JP, U) Actual opening 61-175547 (JP, U) Actual opening 63-87245 (JP, U) Actual opening Flat 1-118137 (JP, U)

Claims (3)

[Claims] 1. An intake cylinder having a throttle valve shaft which is inserted substantially across the center of the intake cylinder and a throttle valve which is fixed to the throttle shaft and is disposed inside the intake cylinder, the intake cylinder being made of an aluminum-based material. In the throttle valve assembly manufactured by, the throttle valve shaft is made of a material containing aluminum whose main coefficient of thermal expansion is substantially the same as that of the material of the intake cylinder, and an oxide film is formed on the surface of the material containing aluminum as a main component. A throttle valve assembly characterized by being formed and surface-reinforced. 2. A suction valve having a throttle valve shaft inserted substantially across the center of the intake cylinder and a throttle valve fixed to the throttle shaft and disposed in the intake cylinder, the intake cylinder being made of an aluminum-based material. In the throttling valve assembly, the throttle valve shaft is made of a material whose main coefficient of thermal expansion is substantially the same as that of the material of the intake cylinder, and the surface layer of the material whose main ingredient is aluminum is porous. A throttle valve assembly, characterized in that it is converted into a hard aluminum oxide, and its porous structure is impregnated with a tetrafluoride resin to strengthen its surface. 3. A throttle valve assembly having a throttle valve shaft which is inserted substantially across the center of an intake cylinder, and a throttle valve which is fixed to the throttle valve shaft and is disposed in the intake cylinder. The shaft is made of a material having substantially the same thermal expansion coefficient as the material of the intake cylinder, one side of the throttle valve shaft is fixed to a bearing to restrict axial displacement of the throttle valve shaft, and the other side is loosely fitted to the bearing. A throttle assembly characterized by.