Hatada, Naozumi; Iida, Makoto; Takeuchi, Yutaka; Tamaki, Shigeo;

Throttle body

A lightweight, low cost throttle body and throttle valve placed in the body, both formed of resins, that resolve the problem of excessively large gap formation is disclosed. Circumferentially oriented filler contained in a resin forming a throttle valve compensates to make the radial linear expansion coefficient of the throttle valve substantially equal to that of a bore. Grooves are formed on concentric circles in the throttle valve to orient filler circumferentially. A throttle valve provided with circumferentially oriented filler can be formed by impregnating an aggregate formed by circumferentially arranging the filler with a resin and curing the resin. A rib is formed in a part near a throttle shaft to control molding shrinkage so that the roundness of the bore is small.

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What is claimed is:

1. A throttle body comprising:

a throttle shaft extended substantially diametrically across an intake cylinder bore; and

a throttle valve fixed to the throttle shaft and contained in the bore;

wherein the bore and the throttle valve are made of a resin containing filler;

a plurality of grooves are arranged in a zigzag arrangement like concentric circles on at least one surface of main surface and back surface of the throttle valve; and

the difference between circumferential deformation of the bore and radial deformation of the throttle valve is in the range of 0 μm to 40 μm at temperatures in the range of -40° C. to 120° C.

2. A throttle body comprising:

an intake cylinder bore; and

a throttle valve;

wherein the throttle valve and the bore are made of resins containing filler;

a plurality of grooves are arranged partly on concentric circles on at least one surface of main surface and back surface of the throttle valve; and

the difference between the linear expansion coefficient of the throttle valve and that of the bore is in the range of 0 to 4×10^-6/° C.

3. A throttle body comprising:

a throttle shaft extended substantially diametrically across an intake cylinder bore; and

a throttle valve fixed to the throttle shaft and contained in the bore;

wherein the bore and the throttle valve are made of a resin containing filler;

a plurality of grooves are arranged partly like concentric circles on one side and a plurality of ribs are arranged like concentric circles on the other side on at least one surface of main surface and back surface of the throttle valve;

and the filler is substantially circumferentially oriented in the throttle valve.

4. A throttle valve comprising:

a throttle shaft extended substantially diametrically across an intake cylinder bore; and

a throttle valve fixed to the throttle shaft and contained in the bore;

wherein the bore and the throttle valve are made of a resin containing filler; and

the throttle valve is made of a resin different in filler content from that forming the bore to make the radial linear expansion coefficient of the throttle valve nearly equal to the circumferential linear expansion coefficient of the bore.

5. The throttle body according to claim 4, wherein at least a peripheral part of the throttle valve facing the bore wall of the bore is made of a resin containing a fluorocarbon resin or is coated with a fluorocarbon resin.