JP2019035392A - Bearing support structure and throttle device - Google Patents

Abstract

To provide a technology capable of preventing holding force for holding a bearing from lowering due to thermal expansion at a cylindrical part.SOLUTION: A bearing support structure comprises: a body; and a cylindrical part projecting from a surface of the body, and supporting a bearing, wherein the bearing is arranged on an inner peripheral side. On an outer peripheral surface of the cylindrical part, three or more grooves are arranged so as to extend from a tip of the cylindrical part toward the body. The bearing support structure is, for example, useful in a case of being applied to a throttle device comprising a bearing for supporting a shaft of an on-off valve.SELECTED DRAWING: Figure 7

Description

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

  Patent Document 1 discloses a bearing support structure that is employed in a crankcase of an internal combustion engine. A circular hole into which the bearing is inserted is provided in the inner wall of the crankcase. On the inner peripheral surface of the circular hole, a plurality of trapezoidal piece members are arranged along the inner peripheral surface. The side surface of the piece member corresponding to the lower base 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 having a larger linear expansion coefficient than aluminum. When the crankcase is thermally expanded, a gap is generated between the inner peripheral surface of the circular hole and the outer peripheral surface of the bearing. At this time, the piece member is thermally expanded so that the side surface of the piece member corresponding to the lower base of the trapezoid protrudes toward the inside of the circular hole. Thereby, a bearing is hold | maintained by the piece member.

JP 2014-25547 A

  In the bearing support structure described above, a piece member made of a material different from that of the crankcase must be disposed.

  In this specification, the technique for suppressing that the holding force for hold | maintaining a bearing by thermal expansion of a cylindrical part falls without using a piece member is provided.

  The bearing support structure disclosed in the present specification includes a main body and a cylindrical portion that protrudes from the surface of the main body and supports a bearing disposed on the inner peripheral side. Three or more grooves extending from the tip of the head toward the main body are arranged.

  As a result of examining a bearing support structure that suppresses a decrease in holding force that holds the bearing due to thermal expansion, according to the above configuration, the amount of expansion of the portion where the groove is disposed (hereinafter referred to as “arrangement portion”) However, it turned out that it becomes small compared with the expansion amount in the structure where the groove | channel is not arrange | positioned.

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

  The three or more grooves may have the same shape. 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 arrangement parts are substantially equal, and the bearing is held by the three or more arrangement parts arranged at equal intervals. As a result, it is possible to suppress the bearing shaft from being displaced from the cylindrical portion shaft.

  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 structure, the fall of the retention strength with respect to the bearing by thermal expansion can be suppressed appropriately.

  It is effective to employ the above bearing support structure in the throttle device. That is, the throttle device is supported by the main body including the intake pipe, the cylindrical portion protruding from the surface of the main body to the side away from the intake pipe, the bearing disposed on the inner peripheral side of the cylindrical portion, and the bearing. And an on-off valve that opens and closes the intake pipe. Three or more grooves extending from the tip of the cylindrical portion toward the main body may be disposed on the outer peripheral surface of the cylindrical portion. According to this configuration, in the throttle device, by disposing three or more grooves in the cylindrical portion, it is possible to suppress a decrease in holding force with respect to the bearing due to thermal expansion without using a piece member.

The perspective view of the throttle device of the 1st example is shown. Sectional drawing in the II-II plane of FIG. 1 is shown. Fig. 3 shows an enlarged view of range III in Fig. 2; The top view of the throttle main body of 1st Example is shown. The cylindrical part of a comparative example is shown. The simulation result in a comparative example is shown. The cylindrical part of 1st Example is shown. The simulation result in 1st Example is shown. The cylindrical part of 2nd Example is shown. The simulation result in 2nd Example is shown. The cylindrical part of a modification is shown.

(First embodiment)
(Configuration of throttle device)
The bearing support structure of the first embodiment will be described with reference to the drawings. The bearing support structure of this embodiment is employed in the throttle device 2. 1 to 3 show the throttle device 2. The throttle device 2 is mounted on a vehicle including an internal combustion engine such as an automobile. The throttle device 2 is disposed on the intake path of the vehicle. The throttle device 2 opens and closes the intake path in accordance with instructions from the vehicle ECU (Engine Control Unit: not shown). 2 shows a cross-sectional view taken along the II-II plane of FIG. 1 along the axis of the shaft 12 of the on-off valve 10 described later.

  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. 1 and 2, the illustration of a cover that covers the housing 42 of the throttle body 4 is omitted.

  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 passes through the throttle body 4 on the bottom surface side of the housing 42.

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

  The bearing 8 is made of a steel material such as stainless steel. The bearing 8 is disposed 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 disposed 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 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 about the axis of 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.

(Configuration 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. Four grooves 6 a extending from the tip of the cylindrical portion 6 (that is, the end opposite to the bottom surface 42 a of the housing 42) toward the throttle body 4 are disposed on the outer peripheral surface of the cylindrical portion 6. The four grooves 6a have the same shape. 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. The four grooves 6a extend to the bottom surface 42a of the housing 42 (see FIG. 3). In the modification, at least one of the four grooves 6a may not extend to the bottom surface 42a. For example, the groove 6a may extend to an intermediate position from the tip of the cylindrical portion 6 to the bottom surface 42a.

  The throttle device 2 is disposed in the vicinity of the internal combustion engine. The throttle body 4 is exposed to heat from the internal combustion engine and becomes high temperature. In addition, the throttle body 4 is heated by receiving heat from the motor 50. As a result of the high temperature of the throttle body 4, the cylindrical portion 6 and the bearing 8 are thermally expanded. Here, the linear expansion coefficient of the cylindrical part 6 made of aluminum alloy is larger than the linear expansion coefficient of the bearing 8 made of steel. 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 is reduced. The four grooves 6a are arranged in order to suppress a decrease in holding force. Hereinafter, the result of the simulation of the thermal expansion of the cylindrical portion will be described for the present embodiment and the comparative example of FIG.

(Comparison example cylindrical part and simulation results)
With reference to FIG. 5 and FIG. 6, the simulation result of the thermal expansion of the cylindrical part 100 of the comparative example and the cylindrical part 100 will be described. As shown in FIG. 5, the diameter of the outer peripheral surface of the cylindrical part 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. This is the diameter R2 (<R1) of the inner peripheral surface of the cylindrical portion 100. 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 disposed on the outer peripheral surface.

  Here, simulation conditions will be described. As shown in FIG. 2, the base portion 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 configuration of the cylindrical portion was imitated and the base portion of the cylindrical portion was constrained and the tip of the cylindrical portion 100 was not constrained. That is, the base portion of the cylindrical portion does not thermally expand. This condition is common to all simulations described later unless otherwise specified.

  A shape S1 drawn with a thick broken line in FIG. 6 represents the inner peripheral surface of the tip of the cylindrical portion 100 before simulation (that is, before thermal expansion at room temperature). The shape S1 is a circular shape having a diameter R2. On the other hand, a shape S2 drawn by a 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 is thermally expanded, the diameter of the inner peripheral surface of the cylindrical portion 100 is increased, and the amount of expansion is uniform over the entire circumference of the inner peripheral surface.

(Cylindrical portion of first embodiment and simulation result)
With reference to FIG. 7 and FIG. 8, the simulation result of the thermal expansion of the cylindrical part 6 of 1st Example and the cylindrical part 6 is demonstrated.

  First, the shape of the four grooves 6a will be described. When viewed from the axial direction of the cylindrical portion 6, each inner surface of the four grooves 6a has a shape of an arc C1 having a diameter R3. The diameter R3 is not more than the diameter R1 of the outer peripheral surface of the cylindrical portion 6. When viewed from the axial direction of the cylindrical portion 6, the center P <b> 1 of the arc C <b> 1 is located outside the outer peripheral surface of the cylindrical portion 6. In addition, the angle which arises in an outer peripheral surface when forming an arc-shaped groove | channel in the outer peripheral surface of the cylindrical part 6 is chamfered by predetermined roundness.

  Further, the minimum thickness t of the portion where each groove 6a is disposed (hereinafter referred to as “arrangement portion”) 6b is 60 percent of the thickness T of the cylindrical portion 6 (that is, T = (R1−R2) / 2). In order to secure the strength of the cylindrical portion 6, it is desirable that the minimum thickness t of the arrangement portion 6 b is 30 percent or more of the thickness T of the cylindrical portion 6.

  A 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 is different from the expansion amount of the portion other than the arrangement portion 6b (hereinafter, “non-arrangement portion”) 6c. Here, the expansion amount 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 (see shape S2) in the comparative example, while the expansion amount of the non-arrangement portion 6c is larger than the expansion amount in the comparative example.

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

  Moreover, as shown in FIG. 8, the expansion amount of the four arrangement | positioning parts 6b is equal. The four arrangement portions 6 b are arranged at equal intervals along the outer peripheral surface of the cylindrical portion 6. That is, the bearing 8 is held by the four arrangement portions 6b arranged at equal intervals. As a result, it is possible to suppress the shaft of the bearing 8 from being displaced from the shaft of the cylindrical portion 6.

  The phenomenon of thermal expansion as in the shape S3 in FIG. 8 is considered as follows. The non-arranged portion 6 c sandwiched between two adjacent grooves 6 a expands in the radial direction and extends in the circumferential direction of the cylindrical portion 6. As a result, the thermal expansion of the arrangement | positioning part 6b arrange | positioned between the non-arrangement | positioning parts 6c adjacent in the circumferential direction of the cylindrical part 6 is suppressed. As a result, the expansion amount of the arrangement portion 6b is considered to be smaller than the expansion amount in the comparative example.

  As a result of various simulations, the phenomenon of FIG. 8 is 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 is thermally expanded from the tip of the cylindrical portion. It is noticeable in difficult conditions. According to the throttle device 2 of the first embodiment, the cylindrical portion 6 protrudes from the bottom surface 42 a of the throttle body 4. The base portion of the cylindrical portion 6 is cooled by the air passing through the intake pipe 44 located in the vicinity of the bottom surface 42a. As a result, the base of the cylindrical portion 6 is less likely to thermally expand than the tip of the cylindrical portion 6. By arranging the four grooves 6 a in the cylindrical portion 6 of the throttle device 2, the phenomenon shown in FIG. 8 occurs, and a decrease in holding force on the bearing 8 due to thermal expansion of the cylindrical portion 6 can be suppressed.

  In addition, as a result of changing the diameter of the arc shape of the groove 6a and performing a simulation on the cylindrical portion, it has been found that the smaller the arc shape diameter of the groove 6a, the smaller the expansion amount of the arrangement portion 6b. As a result of the simulation, if the arc-shaped diameter 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 appropriately adjusted even after thermal expansion while suppressing a decrease in the holding force with respect to the bearing 8. It was found that it can be maintained.

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

(Second embodiment)
(Cylindrical portion of the second embodiment and simulation results)
With reference to FIG. 9, FIG. 10, the simulation result of the thermal expansion of the cylindrical part 60 of 2nd Example and the cylindrical part 60 is demonstrated.

  In the cylindrical portion 60 of the second embodiment, three grooves 60a are disposed 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.

  A 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, as in the first embodiment, the expansion amount of the placement portion 60b is smaller than the expansion amount (see shape S2) in the comparative example, while the expansion amount of the non-placement portion 60c is small. More than the expansion amount in the comparative example. Furthermore, compared with FIG. 8 showing the simulation result of the first embodiment, the expansion amount of the placement portion 60b is smaller than the expansion amount of the placement portion 6b of the first embodiment. Also in the present embodiment, the bearing 8 is held at three points by the three arrangement portions 60b, and it is possible to suppress a decrease in holding force with respect to the bearing 8 due to thermal expansion of the cylindrical portion 6. The three grooves 60a are an example of “three or more grooves” in the claims.

(Third embodiment)
(Configuration of cylindrical part)
With reference to FIG. 11, the cylindrical part 70 of 3rd Example is demonstrated. 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. The reinforcing member 72 is an annular member, and is made of a material (for example, 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 thermally expand as compared to the base portion of the cylindrical portion 6 of the first embodiment. Also in the present embodiment, as in the first embodiment, it is possible to suppress a decrease in holding force with respect to the bearing 8.

  The embodiments of the technology disclosed in the present specification have been described in detail above. However, these are merely examples, and the bearing support structure and the throttle device disclosed in the present specification are variously modified and changed. Is included.

(Modification 1) The bearing support structure in each of the embodiments described above may be employed in devices other than the throttle device. For example, you may employ | adopt as a crankcase, a motor, a transmission.

(Modification 2) The number of grooves disposed 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, it is sufficient that three or more grooves are disposed on the outer peripheral surface of the cylindrical portion.

(Modification 3) In said 1st Example, the inner surface of the groove | channel 6a is circular arc shape. Alternatively, the inner surface of the groove 6a may be V-shaped, elliptical, or oval.

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

  The technical elements described in this 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 technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

2: Throttle device 4: Throttle body 6, 60, 70, 100: Cylindrical portions 6a, 60a: Grooves 6b, 60b: Arrangement portions 6c, 60c: Non-arrangement portion 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: Reinforcement member C1: Arc P1: Centers S1-S4: Shape T: Thickness t: Minimum thickness

Claims (4)

The body,
A cylindrical portion that protrudes from the surface of the main body and supports a bearing disposed on the inner peripheral side;
With
A bearing support structure in which three or more grooves extending from the tip of the cylindrical portion toward the main body are disposed on the outer peripheral surface 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, wherein a center of the arc shape is located outside the outer peripheral surface when viewed from an axial direction of the cylindrical portion. A main body equipped with an intake pipe;
A cylindrical portion protruding from the surface of the main body to the side away from the intake pipe;
A bearing disposed on the inner peripheral side of the cylindrical portion;
An on-off valve comprising a shaft supported by the bearing, and for opening and closing the intake pipe;
With
The throttle device, wherein three or more grooves extending from the tip of the cylindrical portion toward the main body are disposed on the outer peripheral surface of the cylindrical portion.

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