Intake throttle valve

Abstract

To obtain a shaft and bearing assembly structure with fewer parts and lower cost in an intake throttle valve. [Solution] One embodiment is an intake throttle valve (10) comprising a throttle body (12), a throttle valve (15), a throttle shaft (17), a ball bearing (32) that rotatably supports the throttle shaft, a throttle gear (20) that is rotated by an electric actuator, and a mounting member (50) fixed to the throttle gear. The outer ring (33) of the ball bearing is fixed to the throttle body. The throttle shaft has a stepped surface (17c), and the throttle shaft is fixed to the inner ring (34) of the ball bearing by the stepped surface (17c) of the throttle shaft and the mounting member sandwiching the inner ring (34) of the ball bearing.

Description

Technical Field

[0001] The technology disclosed in the present application relates to an intake throttle valve.

Background Art

[0002] Vehicles such as automobiles, motorcycles, mopeds, and ships equipped with an engine usually have an intake throttle valve (throttle) for controlling the intake air amount to the engine. The intake throttle valve usually opens and closes an intake passage formed in a body by rotating a shaft fixed to a throttle valve (disk) with an electric motor. The rotation of the electric motor is transmitted to the shaft via a gear train, and a final gear called a throttle gear is fixed to the shaft. The shaft is rotatably supported by a bearing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The intake throttle valve disclosed in Japanese Patent Application Laid-Open No. 2008-150971 discloses a method of reliably fixing a lever for controlling the opening and closing of the throttle valve to the shaft while rotatably supporting the shaft by a bearing. However, this intake throttle valve is not electrified and does not have a throttle gear. Even if a throttle gear is attached to the lever of this document, since the fixing between the shaft and the inner ring of the bearing is made using a collar or a cup member, the structure is complicated. Therefore, an assembly structure of a shaft and a bearing with a small number of parts and low cost is desired.

Means for Solving the Problems

[0005] One aspect of this technology is an intake throttle valve comprising a throttle body forming a fluid passage, a throttle valve disposed in the fluid passage for opening and closing the fluid passage, a throttle shaft fixed to the throttle valve, a ball bearing rotatably supporting the throttle shaft, a throttle gear rotated by an electric actuator, and a mounting member fixed to the throttle gear, wherein the outer ring of the ball bearing is fixed to the throttle body, the throttle shaft has a stepped surface, and the throttle shaft is fixed to the inner ring of the ball bearing by the stepped surface of the throttle shaft and the mounting member sandwiching the inner ring of the ball bearing. This allows for a low-cost assembly of the shaft and bearing with a small number of parts.

[0006] In some embodiments, the outer diameter of the throttle shaft at the location of the ball bearing is less than the inner diameter of the inner ring of the ball bearing. This allows the dimensional tolerance of the fit between the throttle shaft and the ball bearing to be set to a clearance fit, eliminating the need for special processes to improve dimensional accuracy, such as polishing the throttle shaft. Furthermore, it becomes possible to use inexpensive ball bearings that do not require press-fitting of the inner ring. As a result, costs can be reduced.

[0007] In some embodiments, the mounting member has a base portion coupled to the throttle gear and a cylindrical portion extending from the base portion toward the ball bearing, and the inner ring of the ball bearing is axially restrained by the cylindrical portion of the mounting member. This allows the inner ring of the ball bearing to be restrained with a mounting member of a simple structure.

[0008] In some embodiments, the mounting member has an L-shaped cross-section. This results in a simple drawn shape for the mounting member, making it easier to manufacture.

[0009] In some embodiments, the throttle gear is coupled to the throttle shaft via crimping, screwing, or welding to the base of the mounting member. This allows the inner ring of the ball bearing to be fixed to the throttle shaft without the need for special additional parts, as the base of the mounting member provides a bonding surface for crimping, screwing, or welding. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view of an intake throttle valve as one embodiment. [Figure 2] This is a magnified view of the portion of the intake throttle valve enclosed by the dashed line in Figure 1. [Figure 3] This is a partially enlarged view corresponding to Figure 2 of an intake throttle valve as another embodiment. [Modes for carrying out the invention]

[0011] Various embodiments of this technology will be described below with reference to the drawings.

[0012] [Intake throttle valve] Figure 1 shows an intake throttle valve 10 as one embodiment, which is installed in vehicles such as automobiles and motorcycles to regulate the amount of air intake to the engine. The intake throttle valve 10 includes a throttle body 12 that forms a fluid passage 13 through which it passes. The fluid passage 13 constitutes part of the intake passage leading to the engine. The throttle body 12 can be made of metal or resin. The intake throttle valve 10 also includes a rotatable disc-shaped throttle valve (disc) 15 that regulates the flow rate through the fluid passage 13. The throttle valve 15 is fixed to a throttle shaft 17 which is rotatably supported by the throttle body 12. The throttle valve 15 is inserted through a slit in the throttle shaft 17 and fixed to the throttle shaft 17 with screws or the like. The throttle shaft 17 is positioned to cross the fluid passage 13 in the diametrical direction and is supported on both sides of the fluid passage 13 via bearings 32 and 19 attached to the throttle body 12. The throttle valve 15 is rotatable from a fully closed position, which is almost perpendicular to the fluid passage 13, to a fully open position, which is almost parallel to the fluid passage 13. When the throttle shaft 17 rotates, the throttle valve 15 opens and closes. The throttle shaft 17 can be made of metal.

[0013] [Motors and transmission mechanisms] The intake throttle valve 10 is equipped with a motor 22 as an electric actuator for driving the throttle valve 15. The rotation output by the motor 22 is transmitted to the throttle shaft 17 via a transmission mechanism. The motor 22 and the transmission mechanism are housed in a housing portion 12a formed in the throttle body 12, and the throttle body 12 is equipped with a lid 12b that closes this housing portion. In one embodiment, the transmission mechanism consists of a drive gear 24 fixed to the output shaft of the motor 22, an intermediate gear 26 rotatably supported in the throttle body 12 via an intermediate shaft, and a throttle gear 20, which is a driven gear, fixed coaxially to the throttle shaft 17. The intermediate gear 26 has a large-diameter tooth portion 26a and a small-diameter tooth portion 26b fixed coaxially to the intermediate shaft, with the drive gear 24 meshing with the large-diameter tooth portion 26a and the teeth portion 28 of the throttle gear 20 meshing with the small-diameter tooth portion 26b. The throttle gear 20 can be made of resin. The throttle shaft 17 is fixed to the throttle gear 20 via a mounting member 50, also called a lever, which will be described later. The motor 22 is controlled by an external electronic control unit (ECU). The opening degree of the throttle valve 15 is adjusted by controlling the rotation direction and amount of rotation of the motor 22.

[0014] [Coil spring] The intake throttle valve 10 includes a coil spring 30 that functions as a torsion spring, biasing the throttle valve 15 toward its default position. One end of the coil spring 30 is attached to the throttle body 12, and the other end is attached to the throttle gear 20, thereby biasing the throttle valve 15 via the throttle gear 20. When the motor 22 is energized (i.e., when the output shaft can be controlled), the throttle valve 15 can be rotated to any position between the fully closed and fully open positions against the biasing force of the coil spring 30. When power to the motor 22 is cut off, the biasing force of the coil spring 30 automatically rotates the throttle valve 15 to its default position, allowing a small amount of air to be supplied to the engine through the fluid passage 13.

[0015] [Ball bearing] As shown in Figure 2, the bearing 32 on the throttle gear 20 side is a ball bearing. The ball bearing 32 has an outer ring 33, an inner ring 34, and a plurality of balls 35 that roll between the inner ring 34 and the outer ring 33. The throttle body 12 has a bearing retaining portion 45. The bearing retaining portion 45 has an inner cylindrical wall surface 45a, and this wall surface 45a holds the outer ring 33 of the bearing 32 by interference fit. The bearing 32 can be positioned axially on the bottom surface 45b of the bearing retaining portion 45. The bearing retaining portion 45 can be configured, for example, as a cylindrical body that protrudes from the throttle body 12 toward the throttle gear 20 (Figure 1). One end of the coil spring 30 is positioned on the outside of the cylindrical body that constitutes this bearing retaining portion 45.

[0016] [Mounting components] The throttle shaft 17 is generally fixed to the throttle gear 20 via an annular mounting member 50. The throttle gear 20 has a through-hole 20a or recess that receives the tip 17a of the throttle shaft 17. The mounting member 50 can be made of metal and can be coupled to the throttle gear 20 by insert molding into the inner wall surface 20b of the through-hole 20a of the partially resin throttle gear 20.

[0017] The throttle shaft 17 is provided with a stepped surface 17c that faces the ball bearing 32. The throttle shaft 17 is fixed to the inner ring 34 of the ball bearing 32 by sandwiching the inner ring 34 of the ball bearing 32 between the stepped surface 17c of the throttle shaft 17 and the mounting member 50. As a result, the throttle shaft 17 and the inner ring 34 of the ball bearing 32 cannot rotate relative to each other, and at the same time, the stepped surface 17c of the throttle shaft 17 and the inner ring 34 of the ball bearing 32 are in surface contact, which prevents engine oil and the like flowing in from the fluid passage 13 along the shaft 17 from flowing into the housing portion 12a. The outer diameter d of the throttle shaft 17 can be less than the inner diameter D of the ball bearing 32. Specifically, the dimensional tolerance of the fit between the throttle shaft 17 and the ball bearing 32 can be set to a clearance fit. As a result, special processes to improve dimensional accuracy, such as polishing of the throttle shaft 17, are not required. Furthermore, it becomes possible to use an inexpensive type of ball bearing 32 that does not require clearance fitting of the inner ring 34. As a result, the manufacturing cost of the intake throttle valve 10 can be reduced.

[0018] The mounting member 50 has, for example, a base portion 51 that is coupled to the throttle gear 20 and a cylindrical portion 52 that extends from the base portion 51 toward the ball bearing 32. The base portion 51 can be flat, and its outer circumference 51a is embedded in the throttle gear 20. The inner ring 34 of the ball bearing 32 is axially restrained by the tip surface 52a of the cylindrical portion 52 of the mounting member 50. This allows the inner ring 34 of the ball bearing 32 to be restrained with a mounting member 50 of a simple structure. In one embodiment, the mounting member 50 can have an L-shaped cross-section. That is, the inner circumference 51b of the base portion 51 is circular, and the cylindrical portion 52 extends from the inner circumference 51b of the base portion 51 toward the ball bearing 32. This results in a simple constricted shape for the mounting member 50, making it easy to manufacture. In another embodiment (not shown), the mounting member 50 can have a T-shaped cross-section. In other words, the cylindrical portion 52 extends toward the ball bearing 32 from the portion inside the inner peripheral edge 51b of the base portion 51. For example, the inner peripheral edge 51b of the base portion 51 can be a non-circular shape, such as a wavy or toothed shape, to ensure a secure crimp. In yet another embodiment (not shown), the cylindrical portion 52 of the mounting member 50 may have a trapezoidal cross-section. That is, the diameter can increase from the tip surface 52a toward the base portion 51.

[0019] [Securing by crimping] The throttle gear 20 is coupled to the throttle shaft 17 by caulking the tip 17a of the throttle shaft 17 to the attachment member 50. Specifically, the tip 17a of the throttle shaft 17 is caulked on the surface 51c of the base 51 of the attachment member 50 on the side far from the ball bearing 32. The throttle shaft 17 and the attachment member 50 are prevented from coming off each other by a caulking portion 17b with an increased diameter formed at the tip 17a of the throttle shaft 17. Further, a force for restraining the inner ring 34 of the ball bearing 32 is applied to the attachment member 50 by this caulking process. Therefore, the inner ring 34 of the ball bearing 32 and the attachment member 50 are held between the stepped surface 17c of the throttle shaft 17 and the caulking portion 17b. The surface 51c of the base 51 of the attachment member 50 may be provided with irregularities such as recesses and protrusions to ensure reliable caulking.

[0020] At the time of assembly, first, the throttle shaft 17 is inserted into the insertion hole of the throttle body 12, and while inserting the inner ring 34 of the ball bearing 32 into the tip 17a of the throttle shaft 17, the outer ring 33 is press-fitted into the bearing holding portion 45. The throttle gear 20 in which the attachment member 50 is embedded is inserted into the tip 17a of the throttle shaft 17, and the tip 17a is caulked to the attachment member 50. Next, the throttle valve 15 is inserted into the slit of the throttle shaft 17 and screwed. In this way, when the throttle gear 20 is assembled to the throttle shaft 17, a force for restraining the inner ring 34 of the ball bearing 32 is applied to the attachment member 50 at the same time, and the throttle shaft 17 is fixed to the inner ring 34 of the ball bearing 32, resulting in a simple assembly structure.

[0021] [Fixing by welding] As another embodiment not shown, the throttle gear 20 can also be coupled to the throttle shaft 17 by welding (for example, laser welding) the tip 17a of the throttle shaft 17 to the base 51 of the attachment member 50.

[0022] [Fixing by screwing] As shown in Figure 3, in yet another embodiment, the throttle gear 20 can also be coupled to the throttle shaft 17 by screwing a mounting member 50. Specifically, an axially extending screw hole 17d is formed on the tip surface of the throttle shaft 17. A screw fastener 60, such as a bolt, is screwed into this screw hole 17d, and the mounting member 50 is tightened, with the surface 51c of the base 51 of the mounting member 50 serving as a seating surface for the head 62 of the screw fastener 60. This screwing process applies a force to the mounting member 50 that restrains the inner ring 34 of the ball bearing 32. Therefore, the inner ring 34 of the ball bearing 32 and the mounting member 50 are held between the stepped surface 17c of the throttle shaft 17 and the head 62 of the screw fastener 60.

[0023] Regardless of which method of fastening is used as described above, the base 51 of the mounting member 50 provides a joint surface for crimping, screwing, or welding. This allows the inner ring 34 of the ball bearing 32 to be fixed to the throttle shaft 17 without the need for special additional parts, thereby reducing costs.

[0024] Although specific embodiments have been described above, this technology is not limited to these embodiments, and those skilled in the art can make various substitutions, improvements, and modifications without departing from the purpose of this technology. [Explanation of symbols]

[0025] 10 Intake throttle valve 12 Throttle Body 12a Housing section 12b Lid 13 Fluid passage 15 Throttle valve 17 Throttle shaft 17a Tip 17c Step surface 17b Crimping part 17d screw hole 20 Throttle Gear 20a Penetration 20b Inner wall surface 22 motors 24 drive gears 26 Intermediate gear 26a Large diameter tooth section 26b Small diameter tooth section 28 Teeth 30 Coil Springs 32 (Ball) Bearings 33 Outer ring 34 Inner Ring 35 balls 45 Bearing retaining section 45a Wall surface 45b Base 50 Mounting components 51 Base 51a Outer periphery 51b Inner periphery 51c surface 52 Cylinder part 52a Tip surface 60 Screw fasteners 62 Head

Claims

1. It is an intake throttle valve, A throttle body that forms a fluid passage, A throttle valve is disposed in the fluid passage and opens and closes the fluid passage, A throttle shaft fixed to the throttle valve, A ball bearing that rotatably supports the throttle shaft, A throttle gear that is rotated by an electric actuator, It comprises a mounting member fixed to the throttle gear, The outer ring of the ball bearing is fixed to the throttle body. An intake throttle valve in which the throttle shaft has a stepped surface, and the throttle shaft is fixed to the inner ring of the ball bearing by the stepped surface of the throttle shaft and the mounting member sandwiching the inner ring of the ball bearing.

2. An intake throttle valve according to claim 1, An intake throttle valve in which the outer diameter of the throttle shaft at the position of the ball bearing is less than the inner diameter of the inner ring of the ball bearing.

3. An intake throttle valve according to claim 1 or 2, The mounting member has a base portion coupled to the throttle gear and a cylindrical portion extending from the base portion toward the ball bearing, and the inner ring of the ball bearing is axially restrained by the cylindrical portion of the mounting member, in an intake throttle valve.

4. An intake throttle valve according to claim 3, The aforementioned mounting member is an intake throttle valve having an L-shaped cross-section.

5. An intake throttle valve according to claim 3, An intake throttle valve in which the throttle gear is coupled to the throttle shaft by crimping, screwing, or welding to the base of the mounting member.

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