JP6884667B2 - Bearing support structure and throttle device - Google Patents

Description

The present specification relates to a bearing support structure for supporting a bearing and a throttle device that employs the bearing support structure.

Patent Document 1 discloses a bearing support structure adopted for a crankcase of an internal combustion engine. The inner wall of the crankcase is provided with a circular hole into which the bearing is inserted. A plurality of trapezoidal piece members are arranged along the inner peripheral surface of the circular hole. The side surface of the piece member corresponding to the lower bottom of the trapezoid is in contact with the outer peripheral surface of the bearing. The material of the crankcase is aluminum, and the material of the piece member is zinc, which has a larger coefficient of linear expansion than aluminum. When the crankcase thermally expands, a gap is created between the inner peripheral surface of the circular hole and the outer peripheral surface of the bearing. At this time, the piece member thermally expands so that the side surface of the piece member corresponding to the lower bottom of the trapezoid protrudes toward the inside of the circular hole. As a result, the bearing is held by the piece member.

Japanese Unexamined Patent Publication No. 2014-25547

In the above bearing support structure, a piece member whose material is different from that of the crankcase must be arranged.

The present specification provides a technique for suppressing a decrease in the holding force for holding a bearing due to thermal expansion of a cylindrical portion without using a piece member.

The bearing support structure disclosed in the present specification includes a main body and a cylindrical portion that projects from the surface of the main body and supports a bearing arranged on the inner peripheral side, and a cylindrical portion is provided on the outer peripheral surface of the cylindrical portion. Three or more grooves extending from the tip of the cylinder toward the main body are arranged, and the grooves have a bottom in the radial direction of the cylindrical portion .

As a result of examining a bearing support structure that suppresses a decrease in the holding force for holding the bearing due to thermal expansion, according to the above configuration, the amount of expansion of the portion where the groove is arranged (hereinafter, "arranged portion") However, it was found that the amount of expansion was smaller than that in the structure in which the groove was not arranged.

According to the above bearing support structure, the amount of expansion of the three or more arranged portions formed by the three or more grooves is reduced. As a result, since the bearing is held at three or more points by the three or more arranged portions, it is possible to suppress a decrease in the holding force for the bearing due to thermal expansion of the cylindrical portion.

The three or more grooves may have the same shape as each other. The three or more grooves may be arranged at equal intervals along the outer peripheral surface of the cylindrical portion. According to this configuration, the expansion amounts of the three or more arrangements are substantially equal, and the bearings are held by the three or more arrangements arranged at equal intervals. As a result, it is possible to prevent the shaft of the bearing from deviating from the shaft of the cylindrical portion.

Each inner surface of the three or more grooves may have an arc shape when viewed from the axial direction of the cylindrical portion. The diameter of the arc shape may be equal to or less than the diameter of the outer peripheral surface of the cylindrical portion. The center of the arc shape may be located outside the outer peripheral surface when viewed from the axial direction of the cylindrical portion. According to this configuration, it is possible to appropriately suppress a decrease in the holding force on the bearing due to thermal expansion.

It is effective to adopt the above bearing support structure for the throttle device. That is, the throttle device is supported by a main body having an intake pipe, a cylindrical portion protruding from the surface of the main body to the side separated from the intake pipe, a bearing arranged on the inner peripheral side of the cylindrical portion, and bearings. The shaft is provided, and an on-off valve for opening and closing the intake pipe may be provided. Three or more grooves extending from the tip of the cylindrical portion toward the main body are arranged on the outer peripheral surface of the cylindrical portion, and the grooves may have a bottom in the radial direction of the cylindrical portion. According to this configuration, in the throttle device, by arranging three or more grooves in the cylindrical portion, it is possible to suppress a decrease in the holding force with respect to the bearing due to thermal expansion without using a piece member.

The perspective view of the throttle device of 1st Example is shown. The cross-sectional view in the II-II plane of FIG. 1 is shown. An enlarged view of the range III of FIG. 2 is shown. The plan view of the throttle body of 1st Example is shown. The cylindrical part of the comparative example is shown. The simulation results in the comparative example are shown. The cylindrical portion of the first embodiment is shown. The simulation result in the first embodiment is shown. The cylindrical portion of the second embodiment is shown. The simulation result in the second embodiment is shown. The cylindrical part of the modified example is shown.

(First Example)
(Throttle device configuration)
The bearing support structure of the first embodiment will be described with reference to the drawings. The bearing support structure of this embodiment is adopted in the throttle device 2. 1 to 3 show a throttle device 2. The throttle device 2 is mounted on a vehicle having an internal combustion engine such as an automobile. The throttle device 2 is arranged on the intake path of the vehicle. The throttle device 2 opens and closes the intake path according to an instruction from the vehicle's ECU (abbreviation of Engine Control Unit: not shown). Note that FIG. 2 shows a cross-sectional view taken along the axis of the shaft 12 of the on-off valve 10 described later in the II-II plane of FIG.

As shown in FIGS. 1 to 3, the throttle device 2 employs a bearing support structure including a throttle body 4 and a cylindrical portion 6. In addition to this bearing support structure, the throttle device 2 includes a bearing 8, an on-off valve 10, a throttle gear 30, intermediate gears 32 and 34, a motor gear 36, and a motor 50. Note that in FIGS. 1 and 2, the cover covering the housing 42 of the throttle body 4 is not shown.

The throttle body 4 is made of an aluminum alloy. The throttle body 4 includes a housing 42 and an intake pipe 44. The housing 42 accommodates the gears 30 to 36 and the motor 50. The intake pipe 44 is connected to the intake path of the vehicle. The intake pipe 44 penetrates the throttle body 4 on the bottom surface side of the housing 42.

As shown in FIGS. 2 and 3, the cylindrical portion 6 projects from the bottom surface 42a of the housing 42 toward the opening of the housing 42. In other words, the cylindrical portion 6 projects from the bottom surface 42a to the side separated from the intake pipe 44.

The bearing 8 is made of a steel material such as stainless steel. The bearing 8 is arranged on the inner peripheral side of the cylindrical portion 6. Specifically, the bearing 8 is press-fitted inside the cylindrical portion 6. As a result, the bearing 8 is supported by the cylindrical portion 6.

The on-off valve 10 is arranged in the intake pipe 44. The on-off valve 10 includes a shaft 12. The shaft 12 is rotatably supported by the throttle body 4 via a bearing 8. The on-off valve 10 opens and closes the intake pipe 44 by rotating along with the shaft 12.

A throttle gear 30 is fixed to one end of the shaft 12. The throttle gear 30 is made of resin. The throttle gear 30 meshes with the intermediate gear 32. The intermediate gear 32 is fixed adjacent to the intermediate gear 34. The intermediate gear 34 meshes with the motor gear 36. The intermediate gears 32 and 34 are rotatably supported by the throttle body 4.

The motor gear 36 is fixed to the drive shaft of the motor 50. The motor 50 is driven according to a signal from the ECU. When the motor 50 is driven, the drive shaft rotates. As a result, the throttle gear 30 is rotated via the motor gear 36 and the intermediate gears 34 and 32. As a result, the on-off valve 10 is rotated around the shaft 12 via the shaft 12. The motor gear 36 and the intermediate gears 34 and 32 are made of the same resin as the throttle gear 30.

(Construction of cylindrical part)
The cylindrical portion 6 will be described with reference to FIG. FIG. 4 is a plan view of the throttle body 4 as viewed from the axial direction of the cylindrical portion 6. On the outer peripheral surface of the cylindrical portion 6, four grooves 6a extending from the tip of the cylindrical portion 6 (that is, the end opposite to the bottom surface 42a of the housing 42) toward the throttle body 4 are arranged. The four grooves 6a have the same shape as each other. The four grooves 6a are arranged at equal intervals (that is, at intervals of 90 degrees) along the outer peripheral surface of the cylindrical portion 6. The shape of each groove 6a will be described later with reference to FIG. 7. The four grooves 6a extend to the bottom surface 42a of the housing 42 (see FIG. 3). In the modified example, at least one of the four grooves 6a does not have to extend to the bottom surface 42a. For example, the groove 6a may extend from the tip of the cylindrical portion 6 to an intermediate position from the bottom surface 42a.

The throttle device 2 is arranged in the vicinity of the internal combustion engine. The throttle body 4 is exposed to heat from an internal combustion engine and becomes hot. Further, the throttle body 4 receives the heat of the motor 50 and becomes hot. As a result of the temperature of the throttle body 4 becoming high, the cylindrical portion 6 and the bearing 8 thermally expand. Here, the coefficient of linear expansion of the aluminum alloy cylindrical portion 6 is larger than the coefficient of linear expansion of the steel bearing 8. As a result, the diameter of the inner peripheral surface of the cylindrical portion 6 expands larger than the diameter of the outer peripheral surface of the bearing 8, and the holding force for holding the bearing 8 press-fitted into the cylindrical portion 6 decreases. The above four grooves 6a are arranged to suppress a decrease in holding force. Hereinafter, the results of the simulation of the thermal expansion of the cylindrical portion will be described with respect to this example and the comparative example of FIG.

(Cylindrical part of comparative example and simulation result)
The simulation results of the thermal expansion of the cylindrical portion 100 and the cylindrical portion 100 of the comparative example will be described with reference to FIGS. 5 and 6. As shown in FIG. 5, the diameter of the outer peripheral surface of the cylindrical portion 100 is R1. The diameter R1 is the same as the diameter of the outer peripheral surface of the cylindrical portion 6 of the first embodiment. The diameter of the inner peripheral surface of the cylindrical portion 100 is R2 (<R1). The diameter R2 is the same as the diameter of the inner peripheral surface of the cylindrical portion 6 of the first embodiment. In the cylindrical portion 100, unlike the cylindrical portion 6 of the first embodiment, no groove is arranged on the outer peripheral surface.

Here, the conditions of the simulation will be described. As shown in FIG. 2, the base of the cylindrical portion 6 of the throttle device 2 is fixed to the throttle body 4. The simulation was performed under the condition that the base portion of the cylindrical portion was constrained and the tip of the cylindrical portion 100 was not constrained, imitating the configuration of such a cylindrical portion. That is, the base of the cylindrical portion does not thermally expand. Unless otherwise specified, this condition is common to all simulations described later.

The shape S1 drawn by the thick broken line in FIG. 6 represents the inner peripheral surface of the tip of the cylindrical portion 100 before the simulation (that is, before thermal expansion at room temperature). The shape S1 is a circular shape having a diameter R2. On the other hand, the shape S2 drawn by the thick solid line in FIG. 6 represents the inner peripheral surface of the tip of the cylindrical portion 100 after simulation (that is, after thermal expansion). The shape S2 is a circular shape having a diameter larger than the diameter R2. As shown in the shape S2, when the cylindrical portion 100 thermally expands, the diameter of the inner peripheral surface of the cylindrical portion 100 expands, and the amount of expansion thereof is uniform over the entire circumference of the inner peripheral surface.

(Cylindrical portion of the first embodiment and simulation results)
The simulation results of the thermal expansion of the cylindrical portion 6 and the cylindrical portion 6 of the first embodiment will be described with reference to FIGS. 7 and 8.

First, the shapes of the four grooves 6a will be described. Each inner surface of the four grooves 6a has the shape of an arc C1 having a diameter R3 when viewed from the axial direction of the cylindrical portion 6. The diameter R3 is equal to or less than the diameter R1 of the outer peripheral surface of the cylindrical portion 6. The center P1 of the arc C1 is located outside the outer peripheral surface of the cylindrical portion 6 when viewed from the axial direction of the cylindrical portion 6. The corners generated on the outer peripheral surface when the arc-shaped groove is formed on the outer peripheral surface of the cylindrical portion 6 are chamfered with a predetermined roundness.

Further, the minimum thickness t of the portion (hereinafter, “arranged portion”) 6b in which each groove 6a is arranged is 60% of the thickness T (that is, T = (R1-R2) / 2) of the cylindrical portion 6. In order to secure the strength of the cylindrical portion 6, it is desirable that the minimum thickness t of the arrangement portion 6b is 30% or more of the thickness T of the cylindrical portion 6.

The shape S2 in FIG. 8 represents the inner peripheral surface of the tip of the cylindrical portion 100 after thermal expansion in the comparative example. On the other hand, the shape S3 represents the inner peripheral surface of the tip of the cylindrical portion 6 after thermal expansion. The shape S3 is not circular. Specifically, the expansion amount of the arrangement portion 6b and the expansion amount of the portion other than the arrangement portion 6b (hereinafter, “non-arrangement portion”) 6c are different. Here, the amount of expansion is the difference between the diameter of the inner peripheral surface of the cylindrical portion 6 after thermal expansion and the diameter of the inner peripheral surface of the cylindrical portion 6 before thermal expansion. As shown in FIG. 8, the expansion amount of the arrangement portion 6b is smaller than the expansion amount in the comparative example (see shape S2), while the expansion amount of the non-arrangement portion 6c is larger than the expansion amount in the comparative example.

According to this simulation result, the amount of expansion of the four arranged portions 6b formed by the four grooves 6a is smaller than that of the comparative example. According to this embodiment, since the bearing 8 is held at four points by the four arrangement portions 6b, it is possible to suppress a decrease in the holding force of the cylindrical portion 6 with respect to the bearing 8 due to thermal expansion as compared with the comparative example. Can be done.

Further, as shown in FIG. 8, the expansion amounts of the four arrangement portions 6b are equal. The four arrangement portions 6b are arranged at equal intervals along the outer peripheral surface of the cylindrical portion 6. That is, the bearings 8 are held by the four arrangement portions 6b arranged at equal intervals. As a result, it is possible to prevent the shaft of the bearing 8 from deviating from the shaft of the cylindrical portion 6.

The phenomenon of thermal expansion as shown in the shape S3 of FIG. 8 is considered as follows. The non-arranged portion 6c sandwiched between the two adjacent grooves 6a expands in the radial direction and extends in the circumferential direction of the cylindrical portion 6. As a result, the thermal expansion of the arranged portion 6b arranged between the non-arranged portions 6c adjacent to each other in the circumferential direction of the cylindrical portion 6 is suppressed. As a result, it is considered that the expansion amount of the arrangement portion 6b is smaller than the expansion amount in the comparative example.

As a result of various simulations, the phenomenon of FIG. 8 shows that the base of the cylindrical portion is constrained and the tip of the cylindrical portion is not constrained. In other words, the base of the cylindrical portion thermally expands from the tip of the cylindrical portion. It is prominently seen in difficult conditions. According to the throttle device 2 of the first embodiment, the cylindrical portion 6 projects from the bottom surface 42a of the throttle body 4. The base of the cylindrical portion 6 is cooled by air passing through an intake pipe 44 located near the bottom surface 42a. As a result, the base portion of the cylindrical portion 6 is less likely to thermally expand than the tip of the cylindrical portion 6. By arranging the four grooves 6a in the cylindrical portion 6 of the throttle device 2, the phenomenon of FIG. 8 occurs, and it is possible to suppress a decrease in the holding force of the cylindrical portion 6 with respect to the bearing 8 due to thermal expansion.

Further, as a result of simulating the cylindrical portion by variously changing the diameter of the arc shape of the groove 6a, it was found that the smaller the diameter of the arc shape of the groove 6a, the smaller the expansion amount of the arrangement portion 6b. Then, as a result of the simulation, if the diameter of the arc shape is equal to or less than the diameter R1 of the outer peripheral surface of the cylindrical portion 6, the position of the bearing 8 is appropriate even after thermal expansion while suppressing a decrease in the holding force with respect to the bearing 8. It turned out that it can be maintained.

(Correspondence)
Each of the throttle body 4, the bottom surface 42a, and the four grooves 6a is an example of the "main body", "surface", and "three or more grooves" of the claims.

(Second Example)
(Cylindrical portion of the second embodiment and simulation results)
The simulation results of the thermal expansion of the cylindrical portion 60 and the cylindrical portion 60 of the second embodiment will be described with reference to FIGS. 9 and 10.

In the cylindrical portion 60 of the second embodiment, three grooves 60a are arranged instead of the four grooves 6a of the first embodiment. Each shape of the three grooves 60a is the same as the shape of the groove 6a of the first embodiment. The three grooves 60a are arranged at equal intervals (that is, at intervals of 120 degrees) along the outer peripheral surface of the cylindrical portion 60. Further, the minimum thickness t of the arrangement portion 60b in which the groove 60a is arranged is 60% of the thickness T of the cylindrical portion 60 as in the first embodiment.

The shape S4 in FIG. 10 represents the inner peripheral surface of the tip of the cylindrical portion 6 after the simulation. As shown in FIG. 10, in the shape S4, the expansion amount of the arrangement portion 60b is smaller than the expansion amount in the comparative example (see the shape S2) as in the first embodiment, while the expansion amount of the non-arrangement portion 60c is large. , It becomes larger than the expansion amount in the comparative example. Further, as compared with FIG. 8 showing the simulation result of the first embodiment, the expansion amount of the arrangement portion 60b is smaller than the expansion amount of the arrangement portion 6b of the first embodiment. Also in this embodiment, the bearing 8 is held at three points by the three arrangement portions 60b, and it is possible to suppress a decrease in the holding force of the cylindrical portion 6 with respect to the bearing 8 due to thermal expansion. The three grooves 60a are an example of the "three or more grooves" in the claim.

(Third Example)
(Construction of cylindrical part)
The cylindrical portion 70 of the third embodiment will be described with reference to FIG. The cylindrical portion 70 is the same as that of the first embodiment except that the reinforcing member 72 is embedded in the base portion thereof. The reinforcing member 72 is a ring-shaped member, and is made of a material (for example, a steel material) that is less likely to thermally expand than an aluminum alloy. By embedding the reinforcing member 72 and restraining the base portion of the cylindrical portion 70, the base portion of the cylindrical portion 70 is less likely to undergo thermal expansion as compared with the base portion of the cylindrical portion 6 of the first embodiment. In this embodiment as well, as in the first embodiment, it is possible to suppress a decrease in the holding force with respect to the bearing 8.

Although the embodiments of the techniques disclosed in the present specification have been described in detail above, these are merely examples, and the bearing support structure and the throttle device disclosed in the present specification are variously modified and modified in the above embodiments. Includes what you have done.

(Modification 1) The bearing support structure in each of the above embodiments may be adopted in a device other than the throttle device. For example, it may be used in a crankcase, a motor, a transmission, or the like.

(Modification 2) The number of grooves arranged on the outer peripheral surface of the cylindrical portion is not limited to three or four. For example, five or more grooves may be arranged. Generally speaking, three or more grooves may be arranged on the outer peripheral surface of the cylindrical portion.

(Modification 3) In the first embodiment described above, the inner surface of the groove 6a has an arc shape. Instead, the inner surface of the groove 6a may have a V-shape, an elliptical shape, or an oval shape.

(Modification 4) In the first embodiment described above, the four grooves 6a have the same shape as each other. Instead, at least one of the four grooves 6a may have a different shape (for example, V-shape) from the other grooves. Further, the four grooves 6a may not be arranged at equal intervals along the outer peripheral surface of the cylindrical portion 6. For example, the distance between two adjacent grooves among the four grooves 6a may be an angle other than 90 degrees, for example, 70 degrees or 100 degrees.

In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the techniques illustrated in this specification or drawings achieve a plurality of objectives at the same time, and achieving one of the objectives itself has technical usefulness.

2: Throttle device 4: Throttle body 6, 60, 70, 100: Cylindrical part 6a, 60a: Groove 6b, 60b: Arranged part 6c, 60c: Non-arranged part 8: Bearing 10: On-off valve 12: Shaft 30: Throttle gear 32, 34: Intermediate gear 36: Motor gear 42: Housing 42a: Bottom surface 44: Intake pipe 50: Motor 72: Reinforcing member C1: Arc P1: Center S1 to S4: Shape T: Thickness t: Minimum thickness

Claims (4)

With the main body
A cylindrical portion that protrudes from the surface of the main body and supports a bearing arranged on the inner peripheral side, and a cylindrical portion.
With
On the outer circumferential surface of the cylindrical portion is three or more grooves extending toward the main body from the distal end of the cylindrical portion is disposed,
The groove has a bearing support structure having a bottom in the radial direction of the cylindrical portion. The three or more grooves have the same shape as each other.
The bearing support structure according to claim 1, wherein the three or more grooves are arranged at equal intervals along the outer peripheral surface of the cylindrical portion. Each inner surface of the three or more grooves has an arc shape when viewed from the axial direction of the cylindrical portion.
The diameter of the arc shape is equal to or less than the diameter of the outer peripheral surface of the cylindrical portion.
The bearing support structure according to claim 1 or 2, wherein the center of the arc shape is located outside the outer peripheral surface when viewed from the axial direction of the cylindrical portion. The main body with an intake pipe and
A cylindrical portion protruding from the surface of the main body to the side separated from the intake pipe,
Bearings arranged on the inner peripheral side of the cylindrical portion and
An on-off valve that has a shaft supported by the bearing and opens and closes the intake pipe,
With
On the outer circumferential surface of the cylindrical portion is three or more grooves extending toward the main body from the distal end of the cylindrical portion is disposed,
The groove is a throttle device having a bottom in the radial direction of the cylindrical portion.

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