THROTTLE VALVE DEVICE

Abstract

A throttle valve device ideal for small, inexpensive implements is provided. The throttle valve device having a damping member for slowly closing a throttle valve. The throttle valve device (1) has a throttle valve (4) that is fixed to a throttle shaft (5) pivotably supported in an air intake passage (2) and that is urged towards the closed direction, the throttle valve (4) adapted for adjusting the amount of air passing through the air intake passage (2). A through-bore (31) penetrating a shaft bore of the throttle shaft (5) is formed in a body, and a damping member (8) having frictional capabilities is inserted into and supported in the through-bore (31) in a state of pressing against the throttle shaft (5) inserted through the shaft bore (51).

Claims

1. A carburetor comprising a body, an air intake passage through the body, a throttle valve fixed to a throttle shaft pivotably supported in the air intake passage, the throttle shaft is biased towards a closed throttle valve direction, a damping member positioned within the body and operably coupled to the throttle shaft in a state of pressing against the throttle shaft, the damping member configured to dampen the rotation of the throttle shaft.

2. The carburetor of claim 1 further comprising a shaft bore formed in the body, the throttle shaft being received in the shaft bore, a damping member bore formed in the body and penetrating the shaft bore, wherein the damping member is inserted in the damping member bore and supported in a state to frictionally engage the throttle shaft.

3. The carburetor of claim 1, wherein the damping member comprises a damping member having frictional capabilities.

4. The carburetor of claim 3, wherein the damping member comprises an elastic material.

5. The carburetor of claim 2, further comprising a clamp bolt threaded into the damping member bore.

6. The carburetor of claim 5, wherein a compression spring member is disposed between the clamp bolt and the damping member.

7. The carburetor of claim 5, wherein the damping member comprises an elastic material.

8. The carburetor of claim 1, wherein the damping member is a spherical body.

9. The carburetor of claim 2, wherein the damping member is a spherical body.

10. The carburetor of claim 3, wherein the damping member is a spherical body.

11. The carburetor of claim 1, wherein the damping member is columnar in shape, and a surface contacting the throttle shaft forms a concave portion that follows along the outer circumference of the throttle shaft.

12. The carburetor of claim 2, wherein the damping member is columnar in shape, and a surface contacting the throttle shaft forms a concave portion that follows along the outer circumference of the throttle shaft.

13. The carburetor of claim 3, wherein the damping member is columnar in shape, and a surface contacting the throttle shaft forms a concave portion that follows along the outer circumference of the throttle shaft.

14. A carburetor comprising a body, an air intake passage through the body, a throttle valve fixed to a throttle shaft pivotably supported in the air intake passage, the throttle shaft is biased towards a closed throttle valve direction, a damping member positioned within the body and operably coupled to the throttle shaft, the damping member configured to dampen the rotation of the throttle shaft as the throttle shaft rotates towards the closed throttle valve direction, wherein the damping member is columnar in shape with a surface contacting the throttle shaft forming a concave portion that follows along the outer circumference of the throttle shaft.

15. The carburetor of claim 1, wherein damping member is biased to operably engage the throttle shaft.

16. The carburetor of claim 15, further comprising a spring biasing the damping member to operably engage with the throttle shaft.

17. The carburetor of claim 13, wherein damping member is biased to operably engage the throttle shaft.

18. The carburetor of claim 17, further comprising a spring biasing the damping member to operably engage with the throttle shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a sectional view of a preferred embodiment of the present invention;

[0018] FIG. 2 is an enlarged perspective view of a damping member in the embodiment represented in FIG. 1;

[0019] FIG. 3 is an enlarged perspective view of another embodiment of the damping member of the present invention; and

[0020] FIG. 4 is an enlarged perspective view of yet another embodiment of the damping member of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0021] The present invention will be described below based on embodiments shown in the drawings.

[0022] FIGS. 1 and 2 illustrate a preferred embodiment of the throttle valve device of the present invention in a carburetor application. In a throttle valve device 1, a throttle valve 4 for adjusting the amount of air flowing through an air intake passage 2 into a throttle body 3 in whose interior the air intake passage 2 is formed is fixed to a throttle shaft 5 pivotably supported in the air intake passage 2 of the throttle body 3.

[0023] An urging device 6 formed using a coil spring is additionally provided on the throttle shaft 5, and is set so that the throttle valve 4 fixed to the throttle shaft 5 is constantly urged towards the closed direction and constantly returns to idle position when a throttle lever 7 fixed to an end of the throttle shaft 5 is released.

[0024] A through-bore 31 penetrating a shaft bore 51 of the throttle shaft 5 is formed in the throttle body 3, and a spherical damping member 8 having frictional capabilities and being made of, for example, a stable rubber material is inserted into the through-bore 31. A clamp bolt 81 is threaded into the through-bore 31 from the outside, and the damping member 8 is supported in a state of being pressed against the throttle shaft 5.

[0025] As in conventional throttle valve devices, according to the present embodiment configured as described above, a throttle lever 7 affixed to an end of the throttle shaft 5 is caused to rotate against the urging force of the urging device 6 via, for example, a connected accelerator wire, thereby causing the throttle shaft 5 to rotate in the open direction, opening the throttle valve 4 provided in the air intake passage 2, and increasing the amount of air drawn in, whereby the engine is made to rotate at higher speed.

[0026] When, in order to cease high-speed rotation, an accelerator (not illustrated) is released and the throttle lever 7 is returned to the original idle position, the throttle shaft 5 fixed to the throttle lever 7 rotates towards the closed direction due to the urging force of the urging device 6, returning to the original idle position. In this embodiment, a damping member 8 having frictional force is in contact with the throttle shaft 5 in a state of being pressed against the shaft, so that the return to the idle position occurs slowly over time rather than suddenly, as in conventional examples.

[0027] Therefore, it is possible to effectively prevent precipitous drops in engine rotation speed, stalling of the engine, and emission of exhaust gases or the like as caused by the air-fuel ratio being rich when the throttle shaft 5 returns to the idle position.

[0028] In particular, in the present embodiment, it is acceptable merely for a through-bore 31 communicating with the shaft bore 51 of the throttle shaft 5 to be formed in the throttle body 3 and for the damping member 8 to be supported in a pressed state therein. The present embodiment does not differ in external appearance from the prior art; it is readily constructed, light in weight, and capable of being inexpensively provided. The present embodiment is ideally used in engines installed in small, comparatively inexpensive hand-held devices such as chainsaws and trimmers.

[0029] In particular, since only the damping member 8 and the clamp bolt 81 are necessary in the present embodiment, the number of parts can be kept small. Also, by virtue of the damping member 8 comprising an elastic material, it can be readily supported in a state of pressing against the throttle shaft merely by the clamp bolt 81 being pressed against the damping member.

[0030] FIGS. 3 and 4 illustrate another embodiment of the damping member 8 according to the present invention. FIG. 3 depicts a compression spring member 82 disposed between the damping member 8 and the clamp bolt 81. An advantage is presented in the present embodiment in that a material other than an elastic material can be used for the damping member 8, which is preferable in instances where high friction or durability is required.

[0031] In the embodiment illustrated in FIG. 4, the damping member 8 is columnar in shape, a concave portion fitting the outer circumference of the throttle shaft 5 is formed in a surface 83 contacting the throttle shaft 5, the surface 83 being a distal end surface of the damping member 8, and a greater contact surface can be obtained. This embodiment can be applied when high friction is necessary.

[0032] While an instance of the present embodiment being used in a carburetor has been described, it shall be apparent that the present invention can also be applied to other implements in which an air intake passage is controlled.

KEY

[0033] 1 Throttle valve device [0034] 2 Air intake passage [0035] 3 Throttle body [0036] 4 Throttle valve [0037] 5 Throttle shaft [0038] 6 Urging device [0039] 7 Throttle lever [0040] 8 Damping member [0041] 81 Clamp bolt

[0042] While the invention is susceptible to various modifications, and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the invention is not to be limited to the particular forms or methods disclosed, but to the contrary, the invention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the appended claims.