Linear motion conversion device

Abstract

A linear motion conversion device (1) comprises a holding part (14B) that holds a guide member (15) between the holding part (14B) and the cylinder part (11) in the linear motion direction of a linear motion part (13B) to restrict movement of the guide member (15) in the linear motion direction of the linear motion part (13B).

Description

Linear motion conversion device 【0001】 The present disclosure relates to a linear motion conversion device. 【0002】 Patent Document 1 discloses a ball screw device in which a part of a cylindrical shaft is accommodated in a fixed groove surface of the inner surface of a housing, and the rotation of a flange protruding radially from a nut body is restricted by the shaft. 【0003】 Japanese Patent No. 7477062 【0004】 In the linear motion conversion mechanism disclosed in Patent Document 1, a retaining ring is provided on the housing to prevent the shaft from coming off, but there is room for improvement in terms of production cost. One aspect of the present disclosure aims to reduce the production cost of the linear motion conversion device. 【0005】 In order to solve the above problems, a linear motion conversion device according to one aspect of the present disclosure converts the rotational motion of a rotating part into the linear motion of a linear motion part, and in the linear motion conversion device that linearly moves a piston inside a cylinder part by the linear motion part, a restricted part that is displaced together with the linear motion part and the piston, a guide member that restricts the rotational motion of the linear motion part or the piston and allows the linear motion of the restricted part, the linear motion part or the piston, and a clamping part that sandwiches the guide member in the linear motion direction of the linear motion part between the guide member and the cylinder part and restricts the movement of the guide member in the linear motion direction of the linear motion part, and the clamping part is at least one of a bearing in which an outer ring is fixed to the cylinder part and a rotating part is inserted through an inner ring, and a buffer part that buffers an impact caused by the linear motion of the linear motion part or the restricted part. 【0006】 According to one aspect of the present disclosure, the production cost of the linear motion conversion device can be reduced. 【0007】 It is a schematic diagram showing a configuration example of a linear motion conversion device according to Embodiment 1 of the present disclosure. It is a schematic diagram showing a configuration example of a linear motion conversion device according to Embodiment 2 of the present disclosure. 【0008】[Embodiment 1] Figure 1 is a schematic diagram showing an example configuration of a linear motion converter according to Embodiment 1 of the present disclosure. The hydraulic pressure generator 1 shown in Figure 1 is an example of a linear motion converter and comprises a cylinder section 11, a piston 12, a linear motion converter mechanism 13, a bearing 14, a guide member 15, and an electric motor 16. Hereinafter, the forward direction and the reverse direction are defined as shown by the arrows in Figure 1. The forward direction is the direction in which the piston 12 moves linearly to reduce the hydraulic pressure chamber 20. 【0009】 The linear motion conversion mechanism 13 has a rotating part 13A, a linear motion part 13B, and a flange 13C. The rotating part 13A is, for example, a screw shaft. The axial direction of the rotating part 13A is parallel to the forward and backward directions. The rotating part 13A rotates when the rotational motion of the motor shaft 16A of the electric motor 16 is transmitted to it. The linear motion part 13B is, for example, a nut. The linear motion part 13B converts the rotational motion of the rotating part 13A into linear motion. The piston 12 is connected to the linear motion part 13B and moves linearly in conjunction with the linear motion part 13B. The flange 13C is an example of a restricted part and is connected to the linear motion part 13B. 【0010】 The bearing 14 has an inner ring 14A and an outer ring 14B. The rotating part 13A of the linear motion conversion mechanism 13 is inserted through the inner ring 14A of the bearing 14. The outer ring 14B of the bearing 14 is fixed to the cylinder part 11 and does not move in the forward or backward direction. For example, the outer ring 14B of the bearing 14 may be fixed to the gear case, and the gear case may be fixed to the cylinder part 11, or the outer ring 14B of the bearing 14 may be sandwiched and fixed between the cylinder part 11 and the gear case. 【0011】 Inside the cylinder portion 11, a hydraulic chamber 20 is partitioned by a piston 12. A movable space 21 of the flange 13C is provided between the cylinder portion 11 and the linear motion portion 13B of the linear motion conversion mechanism 13. The flange 13C can be displaced together with the linear motion portion 13B in the forward and backward directions inside the movable space 21. 【0012】The guide member 15 is, for example, a columnar pin and extends in the axial direction of the rotating part 13A. The guide member 15 contacts or fits with the flange 13C in the movable space 21, thereby restricting the rotational movement of the flange 13C and allowing the linear movement of the flange 13C. By restricting the rotational movement of the flange 13C, the rotational movement of the linear motion part 13B and the piston 12 is restricted, and the linear motion conversion mechanism 13 can efficiently convert the rotational motion of the electric motor 16 into linear motion. 【0013】 One end 15A of the guide member 15 is supported by the cylinder portion 11. In Figure 1, one end 15A of the guide member 15 is inserted into a groove 11A provided in the cylinder portion 11. By inserting one end 15A of the guide member 15 into the groove 11A of the cylinder portion 11, the guide member 15 is restricted from tilting in the radial and circumferential directions of the cylinder portion 11 and from moving in the forward direction. The other end 15B of the guide member 15 is supported by the outer ring 14B of the bearing 14. The outer ring 14B of the bearing 14 is the clamping portion according to Embodiment 1. By being supported by the outer ring 14B of the bearing 14, the other end 15B of the guide member 15 is restricted from moving in the backward direction. That is, by being clamped between the cylinder portion 11 and the outer ring 14B of the bearing 14, the guide member 15 is restricted from moving in the forward and backward directions, which are the linear motion directions of the linear motion portion 13B. 【0014】 The length of the guide member 15 from one end 15A to the other end 15B is shorter than the distance from the bottom of the groove 11A of the cylinder portion 11 to the outer ring 14B of the bearing 14, even at the maximum dimensional tolerance. In other words, the guide member 15 is slidably supported between the groove 11A of the cylinder portion 11 and the outer ring 14B of the bearing 14. 【0015】 If the other end 15B of the guide member 15 is to be supported by the cylinder portion 11, the internal structure of the cylinder portion 11 becomes complex, and the production cost of the cylinder portion 11 increases. For example, if the cylinder portion 11 is formed by excavating the cylinder housing, and the other end 15B of the guide member 15 is to be supported by the cylinder portion 11, then the movable space 21 will be formed by excavating radially from a hole drilled in the axial direction of the cylinder portion 11. 【0016】Furthermore, as described in Patent Document 1, when a retaining ring such as a C-ring is installed in the cylinder portion 11 and the other end 15B of the guide member 15 is supported by the retaining ring, sufficient wall thickness is required between the groove into which the retaining ring is fitted and the bearing 14 in order to ensure the durability of the groove. As a result, the axial length of the cylinder portion 11 increases, and material costs increase. In addition, the production cost of the cylinder portion 11 is increased because it is necessary to cut a groove in a direction intersecting the axial direction of the cylinder portion 11 and to fit the retaining ring into that groove. Also, the axial length is increased due to the thickness of the retaining ring and the wall thickness. 【0017】 By sandwiching the guide member 15 between the cylinder portion 11 and the outer ring 14B of the bearing 14, it becomes unnecessary to support the other end 15B of the guide member 15 with the cylinder portion 11 or to provide a retaining ring on the cylinder portion 11. As a result, by excavating the cylinder housing from one direction, the hole through which the piston 12 slides, the movable space 21, and the groove 11A can be easily formed, reducing the production cost of the hydraulic pressure generator 1. Compared to the method of providing a retaining ring on the cylinder portion 11, the axial length of the cylinder portion 11 can be shortened, thus reducing the production cost of the hydraulic pressure generator 1 and allowing the hydraulic pressure generator 1 to be made smaller. As disclosed in Patent Document 1, the hydraulic pressure generator 1 is provided with a bearing 14 through which the rotating portion 13A of the linear motion conversion mechanism 13 is inserted. Since the outer ring 14B of the conventional bearing 14 is used as the member that sandwiches the guide member 15, no new material costs are incurred. 【0018】 The rotational motion of the electric motor 16 is transmitted to the rotating part 13A. The rotational motion of the linear motion part 13B and the flange 13C is restricted by the guide member 15, while linear motion is permitted. The rotational motion of the rotating part 13A is converted into linear motion of the linear motion part 13B and the flange 13C. The flange 13C moves linearly inside the movable space 21. The linear motion of the linear motion part 13B causes the piston 12 to slide inside the cylinder part 11, changing the volume of the hydraulic chamber 20 and generating hydraulic pressure. 【0019】 [Embodiment 2] Another embodiment of the present disclosure is described below. For the sake of convenience of explanation, components having the same function as those described in the above embodiments are denoted by the same reference numerals, and their descriptions are not repeated. 【0020】 Figure 2 is a schematic diagram showing one example configuration of a hydraulic pressure generator equipped with a linear motion converter according to Embodiment 2 of the present disclosure. The hydraulic pressure generator 1 according to Embodiment 2 shown in Figure 2 is equipped with a disc spring 17. The disc spring 17 is a buffer that cushions the impact applied to the bearing 14 etc. from the linear motion part 13B or flange 13C that moves in the retraction direction. The outer diameter of the disc spring 17 is supported by an outer ring 14B, and the outer ring 14B is supported by a gear case. Since the gear case is supported by a cylinder part 11, the radial movement of the cylinder part 11 is restricted. For example, the outer ring 14B may be directly supported by the cylinder part 11, or the disc spring 17 may be directly supported by the cylinder part 11. Because the outer diameter of the disc spring 17 is supported by the outer ring 14B, it can be assembled simultaneously with the bearing 14 during assembly work. Therefore, the assembly position of the disc spring 17 can be aligned while suppressing an increase in the assembly work process, and assembly costs can be reduced. Furthermore, since the disc spring 17 is sandwiched between the outer ring 14B of the bearing 14 and the surface 11B of the cylinder portion 11 facing the outer ring 14B, its movement in the forward and backward directions is restricted. 【0021】 The disc spring 17 is a clamping portion according to Embodiment 2 and supports the other end 15B of the guide member 15. In Embodiment 2, the guide member 15 is clamped between the cylinder portion 11 and the disc spring 17. By clamping the guide member 15 between the cylinder portion 11 and the disc spring 17, the movement of the guide member 15 in the forward and backward directions, which are the directions in which the linear motion portion 13B moves linearly, is restricted. The length of the guide member 15 from one end 15A to the other end 15B is shorter than the distance from the bottom of the groove 11A of the cylinder portion 11 to the disc spring 17, even at the maximum value of the dimensional tolerance. That is, the guide member 15 is supported so as to be slidable between the groove 11A of the cylinder portion 11 and the disc spring 17. 【0022】By sandwiching the guide member 15 between the cylinder portion 11 and the outer ring 14B of the bearing 14 in this manner, it becomes unnecessary to support the other end 15B of the guide member 15 with the cylinder portion 11 or to provide a retaining ring on the cylinder portion 11. This reduces the production cost of the hydraulic pressure generator 1. Furthermore, since the axial length of the cylinder portion 11 can be shortened, the production cost of the hydraulic pressure generator 1 can be reduced and the size of the hydraulic pressure generator 1 can be made smaller. 【0023】 [Modifications] In embodiments 1 and 2 described above, a hydraulic pressure generator 1 was explained as an example of a linear motion converter, but the linear motion converter is not limited to a hydraulic pressure generator. For example, the linear motion converter may be an electric braking device in which a piston 12 presses a friction material against a rotating material that rotates together with the wheels of a vehicle. 【0024】 In the hydraulic pressure generator 1, which is one example of the configuration of the linear motion converter according to the above embodiments 1 and 2, the flange 13C is connected to the linear motion unit 13B. However, the object to which the flange 13C is connected is not limited to the linear motion unit 13B. For example, the flange 13C may be connected to the piston 12. Since the linear motion unit 13B is connected to the piston 12, even if the flange 13C is connected to the piston 12, the flange 13C can restrict the rotation of the linear motion unit 13B. Also, the flange 13C may be integrally formed with the linear motion unit 13B. 【0025】 In the hydraulic pressure generator 1, which is one example of the configuration of the linear motion converter according to the above embodiments 1 and 2, one end 15A of the guide member 15 is supported by the cylinder portion 11 by being inserted into a groove 11A provided in the cylinder portion 11. However, the cylinder portion 11 may support one end 15A of the guide member 15 by a structure other than the groove 11A. For example, one end 15A of the guide member 15 may be supported on the surface of the cylinder portion 11 where the groove 11A was provided, or it may be fixed to a support portion that protrudes from the inner circumferential side wall of the cylinder portion 11. 【0026】[Summary] A linear motion converter according to one aspect of the present disclosure is a linear motion converter that converts the rotational motion of a rotating part into the linear motion of a linear motion part, and causes a piston to move linearly inside a cylinder part by the linear motion part, comprising: a restricted part that displaces together with the linear motion part and the piston; a guide member that restricts the rotational motion of the linear motion part or the piston and allows the linear motion of the restricted part, the linear motion part or the piston; and a clamping part that clamps the guide member between itself and the cylinder part in the direction of linear motion of the linear motion part, and restricts the movement of the guide member in that direction, wherein the clamping part is at least one of a bearing in which the outer ring is fixed to the cylinder part and the rotating part is inserted through the inner ring, and a cushioning part that cushions the impact caused by the linear motion of the linear motion part or the restricted part. In the linear motion converter of the present disclosure, the guide member is clamped between the cylinder part and the clamping part, thereby restricting the movement of the guide member in the direction in which the linear motion part moves linearly. The clamping portion consists of the outer ring and cushioning portion of the bearing, and is composed of parts that have been conventionally used in linear motion converters. By configuring the device to support a guide member between the conventional parts and the cylinder portion, the production cost of the linear motion converter can be reduced compared to conventional designs. For example, the process of forming a groove for installing a retaining ring and the process of fitting the retaining ring into that groove can be omitted, thus reducing production costs. Furthermore, since there is no need to provide that groove in the cylinder portion, there is no need to lengthen the cylinder portion to ensure the durability of the groove, and the dimensions of the cylinder portion in the linear motion direction of the linear motion unit can be shortened, thereby reducing material costs. 【0027】In a linear motion converter according to one aspect of the present disclosure, in the above embodiment, the guide member extends in the direction of linear motion of the linear motion unit, one end is supported by the cylinder portion and the other end is supported by the clamping portion, and the length between the one end and the other end of the guide member is shorter than the distance between the portion of the cylinder portion supporting the one end and the portion of the clamping portion supporting the other end. The linear motion converter of the present disclosure is configured such that the length between the one end and the other end of the guide member is shorter than the distance between the portion of the cylinder portion supporting the one end and the portion of the clamping portion supporting the other end. That is, the guide member is slidably clamped in the direction of linear motion of the linear motion unit. This creates tolerances for the assembly dimensions of the guide member, and the assembly cost of the guide member can be reduced. 【0028】 The clamping portion's movement in the direction of linear motion of the linear motion part is restricted by the cylinder portion. Viewed from the axial direction of the rotating portion, the guide member overlaps the clamping portion. The outer ring of the bearing is fixed to the cylinder portion, and its movement in the direction of linear motion of the linear motion part is restricted by the cylinder portion. Viewed from the axial direction of the rotating portion, the guide member overlaps the outer ring. The outer ring is fixed to the cylinder portion, and a portion of the buffer portion is sandwiched between the outer ring of the bearing and the cylinder portion. The buffer portion's movement in the direction of linear motion of the linear motion part is restricted by the outer ring of the bearing and the cylinder portion. Viewed from the axial direction of the rotating portion, the guide member overlaps the buffer portion and the bearing. Because the clamping portion is restricted from moving in the direction of linear motion of the linear motion part, the clamping portion can appropriately restrict the movement of the guide member in the direction of linear motion of the linear motion part. By preventing the guide member from contacting the rotating member, such as the outer ring of the bearing, when the linear motion part retracts, damage and wear to the rotating member can be prevented. 【0029】 [Additional Notes] This disclosure is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of this disclosure.

Claims

1. A linear motion conversion device that converts the rotational motion of a rotating part into the linear motion of a linear motion part, and causes a piston to move linearly inside a cylinder part by the linear motion part, comprising: a restricted part that displaces together with the linear motion part and the piston; a guide member that restricts the rotational motion of the linear motion part or the piston and allows the linear motion of the restricted part, the linear motion part or the piston; and a clamping part that clamps the guide member between itself and the cylinder part in the direction of the linear motion of the linear motion part and restricts the movement of the guide member in the direction of the linear motion of the linear motion part, wherein the clamping part is at least one of the following: a bearing in which the outer ring is fixed to the cylinder part and the rotating part is inserted through the inner ring; and a buffering part that buffers the impact caused by the linear motion of the linear motion part or the restricted part.

2. The linear motion converter according to claim 1, wherein the guide member extends in the direction of linear motion of the linear motion portion, one end is supported by the cylinder portion, and the other end is supported by the clamping portion, and the length between the one end and the other end of the guide member is shorter than the distance between the portion of the cylinder portion supporting the one end and the portion of the clamping portion supporting the other end.

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