Actuator, and manufacturing method and manufacturing core for the actuator case

Abstract

According to the present invention, in an actuator case, an attachment groove to which an attachment portion of a boot is to be attached is formed on an inner peripheral face of an output hole to enable protection of the attachment portion from outside impact, and to enable formation of the attachment groove at the same time as molding of the actuator case with a resin. A plurality of first protruding walls that protrude inward in the radial direction and are arrayed at first intervals in a circumferential direction of the output hole are formed in an outer edge portion of the output hole. A plurality of second protruding walls that protrude inward in the radial direction and are arrayed at second intervals in a circumferential direction of the output hole are formed in an inner edge portion of the output hole. The first and second protruding walls are arranged not to overlap in a plan view of the output hole. The first and second protruding walls define the attachment groove to which the attachment portion of the boot is to be attached, on the inner peripheral face of the output hole.

Description

[Technical Field]

[0001] The present invention relates to an actuator in which an actuator mechanism is housed in a resin actuator case, an output member of the actuator mechanism is arranged to pass through an output hole of the actuator case, and a boot is attached to the actuator case to cover the outer portion of the output member that protrudes outside the output hole, as well as a method for manufacturing the actuator case and a core used in the manufacturing method. [Background technology]

[0002] Such an actuator is already known, as disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2019 / 187362 publication Summary of the Invention [Problem to be solved by the invention]

[0004] In the actuator described in Patent Document 1, when attaching the boot to the actuator case, an attachment groove surrounding the output hole is formed on the outer peripheral surface of an annular protruding wall that protrudes from the outer surface of the actuator case, and the attachment portion of the boot is attached to this attachment groove. In such an actuator, the attachment portion of the boot is exposed to the outside of the actuator case, and there is a risk that this attachment portion will come off the attachment groove if it receives some kind of impact.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide an actuator in which an attachment groove for attaching the boot attachment portion is formed on the inner surface of the output hole in the actuator case, thereby protecting the attachment portion from external impact, and in which the attachment groove can be formed simultaneously when the actuator case is molded from resin, as well as a manufacturing method and manufacturing core for the actuator case. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides an actuator, the actuator comprising: The actuator includes a resin actuator case and an actuator mechanism housed in the actuator case. an output member of the actuator mechanism is disposed so as to pass through an output hole of the actuator case; a boot that covers an outer portion of the output member that protrudes outside the output hole is attached to the actuator case; At the outer end of the output hole, a plurality of first projecting walls are formed, which project radially inward from the inner peripheral surface of the output hole and are arranged in the circumferential direction of the output hole with first gaps between them, Further, a plurality of second projecting walls are formed at an inner end of the output hole, protruding radially inward from the inner peripheral surface of the output hole and arranged circumferentially of the output hole with second gaps between them, the first and second projecting walls are arranged so as not to overlap with each other in a plan view of the output hole, The first feature is that the first and second protruding walls define an attachment groove on the inner surface of the output hole for attaching the attachment portion of the boot.

[0007] The output member corresponds to an output bolt 19 in an embodiment of the present invention, which will be described later.

[0008] In addition to the first feature, the present invention has a second feature in that the width of the first gap between the first protruding walls is set to be larger than the length of the second protruding wall along the circumferential direction of the output hole.

[0009] Furthermore, in addition to the first feature, the present invention has a third feature in that the protruding height of the second protruding wall is set to be greater than the protruding height of the first protruding wall, and the second protruding wall supports the mounting portion during the process of attaching the mounting portion to the mounting groove.

[0010] Furthermore, in addition to the first feature, the present invention has a fourth feature in that the length of the first protruding wall along the circumferential direction of the output hole is set to be smaller than the length of the second protruding wall along the circumferential direction of the output hole.

[0011] Furthermore, in addition to any one of the first to fourth features, the present invention has a fifth feature in that a reinforcing member is embedded in the mounting portion.

[0012] The present invention also provides a method for manufacturing an actuator case, comprising: The actuator case includes: The device has an output hole through which an output member passes, and an attachment groove into which an attachment portion of a boot that covers the outer portion of the output member that protrudes outside the output hole is attached, and the attachment groove is defined on the inner peripheral surface of the output hole by a plurality of first protruding walls that protrude radially inward from the outer end of the output hole and are lined up in the circumferential direction of the output hole with a first gap therebetween, and a plurality of second protruding walls that protrude radially inward from the inner end of the output hole and are lined up in the circumferential direction of the output hole with a second gap therebetween, the first and second projecting walls are arranged so as not to overlap with each other in a plan view of the output hole, In the step of molding the actuator case with resin, A core is provided that forms the inner peripheral surface of the output hole, and the core is configured by fitting a first core half located on the outer end side of the output hole and a second core half located on the inner end side of the output hole so that they can be separated in the axial direction, First and second recesses that form the first and second projecting walls, respectively, are defined between the first and second core halves, The sixth feature is that resin is injected into a cavity including the first and second recesses, which is defined by the first and second core halves and an outer mold that forms the outer surface of the actuator case.

[0013] Furthermore, the present invention provides a core used in a method for manufacturing an actuator case having a sixth feature, which comprises: The first core half is composed of a hollow cylindrical portion that forms the inner circumferential surface of the mounting groove and a ceiling wall portion that is continuous with the outer end of the hollow cylindrical portion, The ceiling wall portion is provided with a groove portion corresponding to the first protruding wall, Furthermore, the hollow cylindrical portion is provided with a notch corresponding to the gap between the second projecting walls, The second core half is composed of a first cylindrical portion that is removably fitted onto the inner circumferential surface of the hollow cylindrical portion, and a second cylindrical portion that is connected to the first cylindrical portion and has a larger diameter than the first cylindrical portion, The first cylindrical portion is provided with a protrusion that engages with the notch and cooperates with the groove to define the first recess, A seventh feature is that the second recess is defined by the tip surface of the hollow cylindrical portion, the ridge, and the step between the first and second cylindrical portions.

[0014] According to a first feature of the present invention, the outer end of the output hole is formed with a plurality of first protruding walls that protrude radially inward and are spaced apart circumferentially around the output hole. The inner end of the output hole is formed with a plurality of second protruding walls that protrude radially inward and are spaced apart circumferentially around the output hole. The first and second protruding walls are arranged so that they do not overlap each other in a plan view of the output hole. A mounting groove for attaching a boot mounting portion is defined between the first and second protruding walls. Therefore, when molding the actuator case from resin, the first and second protruding walls can be formed using a core that is divided axially within the output hole, thereby defining the mounting groove. Therefore, additional processing to form the mounting groove is not required after molding the actuator case, which can contribute to reducing manufacturing costs. Furthermore, the mounting portion of the boot that is attached to the mounting groove in the output hole is protected from external impact and prevents it from coming off the mounting groove.

[0015] According to the second feature of the present invention, the width of the first gap between the first protrusion walls is set to be larger than the length of the second protrusion wall along the circumferential direction of the output hole, so that when the actuator case is molded from resin, the first and second protrusion walls can be easily and reliably formed by a core that is divided axially within the output hole.

[0016] According to a third feature of the present invention, the protruding height of the second protruding wall is set to be greater than the protruding height of the first protruding wall, and the mounting portion is supported by the second protruding wall during the process of attaching the mounting portion to the mounting groove. This makes it easy to press the mounting portion into the mounting groove, and the second protruding wall prevents the mounting portion from going too far.

[0017] According to a fourth feature of the present invention, by setting the length of the first protrusion wall along the circumferential direction of the output hole to be smaller than the length of the second protrusion wall along the circumferential direction of the output hole, it is possible to more easily press-fit the mounting part into the mounting groove, and after the mounting, the first protrusion wall can prevent the mounting part from coming off the mounting groove.

[0018] According to the fifth feature of the present invention, by embedding a reinforcing member in the mounting portion, the press-fitting force of the mounting portion into the mounting groove can be effectively increased, and the mounting state of the mounting portion in the mounting groove can be stabilized.

[0019] According to the sixth feature of the present invention, when molding the actuator case, the first and second cores can be used to form the output hole with the mounting groove. Therefore, after molding, additional processing to obtain the mounting groove is not required, which can contribute to reducing manufacturing costs.

[0020] According to the seventh feature of the present invention, when molding the actuator case, the output hole having the mounting groove can be reliably formed by using the first and second cores. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is a vertical cross-sectional side view of the actuator according to the embodiment of the present invention. [Figure 2]FIG. 2 is an enlarged view of part 2 of FIG. 1 (however, the output voltage is not shown). [Figure 3] Cross-sectional view taken along line 3-3 in Figure 2. [Figure 4] 10A and 10B are cross-sectional views of a product and a molding die illustrating a molding method for the periphery of an output hole of the actuator case. [Figure 5] FIG. 5 is a cross-sectional view showing the product and the core in FIG. 4 in an exploded state. [Figure 6] Cross-sectional views corresponding to Figure 4 but at different cross-sectional locations. [Figure 7] FIG. 7 is a cross-sectional view showing the product and the core in FIG. 6 in an exploded state. [Figure 8] FIG. 2 is a perspective view showing the product and the core in an exploded state. DETAILED DESCRIPTION OF THE INVENTION

[0022] First, an embodiment of the present invention will be described with reference to the accompanying FIG.

[0023] The actuator A comprises an actuator case 10 and an actuator mechanism 11 housed therein. In this actuator A, the direction in which an output bolt 19 (described later) extends from the actuator case 10 is the front, and the opposite direction is the rear.

[0024] The actuator case 10 has a cylindrical motor case portion 10a, a cylindrical output case portion 10b arranged adjacent to and parallel to the motor case portion 10a, and a gear case portion 10c connecting the rear ends of the motor case portion 10a to the middle portion of the output case portion, and an output hole 15 is provided at the front end of the output case portion 10b.

[0025] The actuator case 10 is also divided into a front half case body 10A and a rear half case cover 10B to enable assembly and disassembly of the actuator mechanism 11. The case body 10A and the case cover 10B are injection molded from resin.

[0026] The actuator mechanism 11 comprises a motor 12 housed in the motor case portion 10a, an output bolt 19 arranged to protrude from the output case portion 10b through the output hole 15 to the outside, a reduction gear train 13 housed from the gear case portion 10c to the output case portion 10b and which reduces the rotation of the rotor shaft 10a of the motor 12 and transmits it to the final gear 14, and a motion conversion mechanism 16 housed in the output case portion 10b and which converts the rotational motion of the final gear 14 into axial motion and transmits it to the output bolt 19.

[0027] The motion conversion mechanism 16 comprises a rotating nut 18 that is supported on the output case portion 10b via a bearing 17 so as to be rotatable but immovable in the axial direction, and a male thread 19a of the output bolt 19 that screws into the female thread 18a of the rotating nut 18. The rotating nut 18 has a large-diameter cylindrical portion 20 that is integrally connected to its rear end and is connected to the final gear 14, so that the rotating nut 18 can rotate together with the final gear 14 but cannot move in the axial direction. In addition, a key 21 that protrudes in the diameter direction is formed at the rear end of the output bolt 19, and a key groove 22 in which the key 21 slidably engages is provided in the output case portion 10b. Therefore, the output bolt 19 can move in its axial direction but cannot rotate.

[0028] The tip of this output bolt 19 that protrudes outside the output hole 15 is connected to a parking brake mechanism (not shown) of the drum brake via a cable 23.

[0029] A plurality of disc springs 24 are housed within the large diameter cylindrical portion 20 of the rotating nut 18 and are compressed as the key 21 moves forward.

[0030] Thus, when the motor 12 is operated, the rotational power of the rotor shaft 10a is reduced and transmitted to the final gear 14 via the gear train 13. When the rotating nut 18 rotates together with the final gear 14, the rotating female thread 18a of the rotating nut 18 applies a thrust force to the output bolt 19 via the male thread 19a, moving it forward or backward, depending on the direction of rotation. When the output bolt 19 is shifted rearward by this thrust force, it pulls the cable 23, putting a parking brake mechanism (not shown) into a braked state. When the output bolt 19 is shifted forward, it relaxes the cable 23, putting the parking brake mechanism into a brake-released state. In this brake-released state, the disc spring 24 is compressed between the rotating nut 18 and the key 21, and the reaction force from this compresses the backlash between the female thread 18a and the male thread 19a.

[0031] In order to close the output hole 15 of the output case portion 10b to protect it from dust and water, a bellows-type boot 25 made of an elastic material is attached to the output case portion 10b so as to cover the outer portion of the output bolt 19.

[0032] 1 and 2, the boot 25 has a large-diameter first mounting portion 26 at one end and a small-diameter second mounting portion 27 at the other end. A metal reinforcing member 28 is embedded in the large-diameter first mounting portion 26, and this first mounting portion 26 is press-fitted into a mounting groove 30 formed on the inner circumferential surface of the output hole 15, while the small-diameter second mounting portion 27 is mounted in an outer circumferential groove 31 at the tip of the output bolt 19. Thus, the first mounting portion 26 is an example of a mounting portion of the present invention.

[0033] The structure of the mounting groove 30 will be described with reference to FIGS. 2, 3, 5 and 8. FIG.

[0034] First, on the inner peripheral surface of the output hole 15, a plurality of (four in the illustrated example) first protruding walls 33 are formed on the outer end side thereof, each with a first gap 35 therebetween, in the circumferential direction of the output hole 15, and on the inner end side thereof, second protruding walls 34, the same number as the first protruding walls 33, are formed on the circumferential direction of the output hole 15, each with a second gap 36 therebetween, protruding radially inward from the inner peripheral surface of the output hole 15. In this case, these first and second protruding walls 33, 34 are arranged so as not to overlap each other in a plan view of the output hole 15 (see FIG. 3). Thus, the mounting groove 30 is defined on the inner peripheral surface of the output hole 15 by these first and second protruding walls 33, 34.

[0035] Furthermore, the width of the first gap 35 between the first projecting walls 33 is set to be larger than the length s2 of the second projecting walls 34 along the circumferential direction of the output hole 15. This is equivalent to saying that the width of the second gap 36 between the second projecting walls 34 is set to be larger than the length s1 of the first projecting walls 33 along the circumferential direction of the output hole 15.

[0036] Furthermore, the protruding height t2 of each second protruding wall 34 from the inner circumferential surface of the output hole 15 (i.e., the bottom surface of the mounting groove 30) is set to be larger than the protruding height t1 of each first protruding wall 33 from the inner circumferential surface of the output hole 15. This can also be said as the diameter of an imaginary circle tangent to the tip surfaces of all the second protruding walls 34 is set to be larger than the diameter of an imaginary circle tangent to the tip surfaces of all the first protruding walls 33.

[0037] In addition, the length s1 of each first projecting wall 33 along the circumferential direction of the output hole 15 is set to be smaller than the length s2 of each second projecting wall 34 along the circumferential direction of the output hole 15.

[0038] Moreover, the inner diameter D2 of the mounting groove 30 is set to be slightly smaller than the outer diameter D1 of the first mounting portion .

[0039] At the outer edge of the output hole 15 , a tapered press-fit guide surface 40 that continues to the outer end surface of the first projecting wall 33 is formed.

[0040] Next, the operation of this embodiment will be described.

[0041] To mount the first mounting portion 26 of the boot 25 in the mounting groove 30 of the output case portion 10b, the first mounting portion 26 is press-fitted toward the tapered press-fit guide surface 40 of the output case portion 10b. The first mounting portion 26 enters the mounting groove 30 while being compressed in the diameter-reducing direction by the first protruding wall 33, and is supported by the second protruding wall 34, preventing it from going too far. The first protruding wall 33 also prevents the first mounting portion 26 from coming out of the mounting groove 30. Furthermore, a set load is applied to the first mounting portion 26 in the diameter-reducing direction by the bottom surface of the mounting groove 30, resulting in a stable mounting state without any rattle. In particular, the reinforcing member 28 embedded in the first mounting portion 26 effectively increases the press-fit reaction force of the first mounting portion 26 into the mounting groove 30, further stabilizing the mounting state of the first mounting portion 26 in the mounting groove 30.

[0042] Incidentally, the plurality of first and second protruding walls 33, 34 that define the mounting groove 30 on the inner peripheral surface of the output hole 15 are arranged so as not to overlap each other in a plan view of the output hole 15, which makes it possible to mold the case main body 10A using a core that is divided into two in the axial direction, as will be described later, and eliminates the need for special additional processing to form the mounting groove 30, which can contribute to reducing manufacturing costs. Moreover, the first mounting part 26 that is attached to the mounting groove 30 inside the output hole 15 protects it from external impacts and can prevent it from coming off the mounting groove 30.

[0043] Next, a method for injection molding the case main body 10A, particularly the front part of the output case portion 10b having the output hole 15, the first and second projecting walls 33, 34 and the mounting groove 30, using resin will be described with reference to FIGS.

[0044] When molding the case body 10A, an outer mold 41 (see Figure 4) that forms the outer surface of the case body 10A and a core 42 (see Figures 5, 7, and 8) that forms the inner surface of the output hole 15 are prepared.

[0045] The outer die 41 is composed of a first outer die half 41a and a second outer die half 41b that are overlapped and separable by a partition surface 43 that passes through the central axis Y of the output hole 15. The core 42 is composed of a first core half 42a located on the outer end side of the output hole 15 and a second core half 42b located on the inner end side of the output hole 15 that are fitted together so as to be separable in the axial direction. First and second recesses 45 and 46 that form the first and second projecting walls 33 and 34, respectively, are defined between these first and second core halves 42a and 42b as follows.

[0046] The first core half 42a is composed of a hollow cylindrical portion 47 that forms the inner circumferential surface of the mounting groove 30, and a ceiling wall portion 48 that is continuous with the outer end of the hollow cylindrical portion 47. A groove portion 49 (see FIG. 5) that corresponds to the first projecting wall 33 is provided in the ceiling wall portion 48. The outer end of the ceiling wall portion 48 is provided with a flange 50 that has a triangular cross section and forms the press-fitting guide surface 40. Meanwhile, the hollow cylindrical portion 47 is provided with a notch 51 that corresponds to the second gap 36 between the second projecting walls 34.

[0047] The second core half 42b is composed of a first cylindrical portion 52 that fits removably onto the inner peripheral surface of the hollow cylindrical portion 47, and a second cylindrical portion 53 that is connected to the first cylindrical portion 52 and has a larger diameter. The first cylindrical portion 52 is provided with a ridge 54 (see FIG. 8) that engages with the notch 51 and cooperates with the groove portion 49 to define the first recess 45. The second recess 46 is defined by the tip surface of the hollow cylindrical portion 47, the ridge 54, and a step portion 55 between the first and second cylindrical portions 52, 53.

[0048] Thus, when the first and second outer mold halves 41a, 41b are overlapped at the partition surface 43 and clamped together, and the first and second core halves 42a, 42b are fitted together inside thereof, a cavity 56 including the first and second recesses 45, 46 is defined between the first and second outer mold halves 41a, 41b and the first and second core halves 42a, 42b, and by injecting resin into this cavity 56, the case body 10A is molded, and at the same time, the multiple first and second protruding walls 33, 34 that define the mounting groove 30, and the press-fit guide surface 40 can be formed. Therefore, after molding the case body 10A, no additional processing is required to form the mounting groove 30, which can reduce manufacturing costs.

[0049] The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment, and various design changes can be made without departing from the present invention as described in the claims.

[0050] This application claims priority to Japanese Patent Application No. 2022-114949, filed July 19, 2022. The entire disclosure of Japanese Patent Application No. 2022-114949, filed July 19, 2022, including the specification, claims, drawings, and abstract, is incorporated herein by reference in its entirety. [Explanation of symbols]

[0051] A···· Actuator s1: Length of the first thrust wall s2: Length of the second thrust wall t1: Height of the first thrust wall t2: Height of the second ledge 10. Actuator case 11. Actuator mechanism 15. Output hole 19. Output member (output bolt) 25 Boots 26...First mounting part as mounting part 28... Reinforcing member 30···Mounting groove 33 First pier 34 Second pier 35...1st gap 36...Second gap 41... Outer mold 41a · 1st outer mold half 41b...Second outer mold half 42...Nakako 42a · 1st core half 42b...Second core half 45···First recess 46...Second recess 47...Hollow cylindrical section 48 Ceiling wall section 49 Groove 51 Notch 52 First cylindrical section 53 Second cylindrical section 54...projection 55...Double section 56···Cavity

Claims

1. An actuator, the actuator comprising: The actuator includes a resin actuator case and an actuator mechanism housed in the actuator case. an output member of the actuator mechanism is disposed to pass through an output hole of the actuator case; a boot that covers an outer portion of the output member that protrudes outside the output hole is attached to the actuator case, a plurality of first projecting walls are formed on the outer end side of the output hole, the first projecting walls projecting radially inward from the inner peripheral surface of the output hole and being arranged in the circumferential direction of the output hole with first gaps between them; Further, a plurality of second projecting walls are formed on the inner end side of the output hole, protruding radially inward from the inner peripheral surface of the output hole and arranged with second gaps in between in the circumferential direction of the output hole, the first and second projecting walls are arranged so as not to overlap with each other in a plan view of the output hole, an actuator, wherein the first and second projecting walls define an attachment groove on the inner circumferential surface of the output hole, into which the attachment portion of the boot is attached;

2. 2. The actuator according to claim 1, An actuator, characterized in that the width of a first gap between the first projecting walls is set to be larger than the length of the second projecting wall along the circumferential direction of the output hole.

3. 2. The actuator according to claim 1, an actuator characterized in that a protruding height of the second protruding wall is set to be greater than a protruding height of the first protruding wall, and the second protruding wall supports the mounting portion during the process of attaching the mounting portion to the mounting groove.

4. 2. The actuator according to claim 1, An actuator, characterized in that the length of the first projecting wall along the circumferential direction of the output hole is set to be smaller than the length of the second projecting wall along the circumferential direction of the output hole.

5. The actuator according to any one of claims 1 to 4, An actuator characterized in that a reinforcing member is embedded in the mounting portion.

6. A method for manufacturing an actuator case, comprising: The actuator case includes: an output hole through which the output member passes; an attachment groove for attaching an attachment portion of a boot that covers an outer portion of the output member that protrudes outside the output hole; The mounting groove is defined on the inner peripheral surface of the output hole by a plurality of first projecting walls that protrude radially inward from the outer end of the output hole and are aligned in the circumferential direction of the output hole with a first gap therebetween, and a plurality of second projecting walls that protrude radially inward from the inner end of the output hole and are aligned in the circumferential direction of the output hole with a second gap therebetween, the first and second projecting walls are arranged so as not to overlap with each other in a plan view of the output hole, In the step of molding the actuator case from resin, a core is provided that forms an inner peripheral surface of the output hole, the core being configured by fitting a first core half located on an outer end side of the output hole and a second core half located on an inner end side of the output hole so as to be separable in the axial direction; First and second recesses are defined between the first and second core halves, forming the first and second projecting walls, respectively; A method for manufacturing an actuator case, characterized in that resin is injected into a cavity including the first and second recesses, which is defined by the first and second core halves and an outer mold that forms the outer surface of the actuator case.

7. A core used in the method for manufacturing an actuator case according to claim 6, the first core half is composed of a hollow cylindrical portion that forms an inner peripheral surface of the mounting groove and a ceiling wall portion that is continuous with an outer end portion of the hollow cylindrical portion, a groove portion corresponding to the first protruding wall is provided in the ceiling wall portion; The hollow cylindrical portion is provided with a notch corresponding to the second gap between the second projecting walls, the second core half is composed of a first cylindrical portion that is removably fitted onto the inner circumferential surface of the hollow cylindrical portion, and a second cylindrical portion that is connected to the first cylindrical portion and has a larger diameter than the first cylindrical portion, The first cylindrical portion is provided with a protrusion that engages with the notch and cooperates with the groove to define the first recess, A core used in a manufacturing method of an actuator case, characterized in that the second recess is defined by the tip surface of the hollow cylindrical portion, the protrusion, and the step portion between the first and second cylindrical portions.

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