Suspension

Abstract

The invention provides a suspension capable of shortening the overall length. An actuator (2) is provided with: a housing (7); a hollow shaft (8) rotatably supported by the housing (7) via bearings (9a, 9b) and having a bottom (8b); a screw shaft (14) connected to the bottom (8b) of the hollow shaft (8) and having a center line common to the hollow shaft (8); and a nut (15) which is in threaded engagement with the screw shaft (14). The nut (15) moves in the axial direction of the lead screw shaft (14) and can enter the space between the hollow shaft (8) and the lead screw shaft (14).

Description

[0001] This application is a divisional application of an invention patent application with an international application date of November 2, 2020, an international application number of PCT / JP2020 / 040999, a priority date of November 19, 2019, an application number of 202080074787.X, and an invention name of “Actuator or Suspension”. Technical Field

[0002] The present invention relates to a suspension having a screw mechanism. Background Art

[0003] In the past, an actuator having a screw mechanism is known. The screw mechanism has a screw shaft and a nut that is threadedly engaged with the screw shaft. When the screw shaft is driven to rotate, the nut moves relatively along the axial direction of the screw shaft. As a suspension assembled with the actuator, that is, a suspension having a screw mechanism, a vehicle height adjustment suspension is known (see patent document 1). When the screw shaft is driven to rotate by a drive unit, the nut moves along the axial direction. The nut is connected to a spring bracket that receives one end of a suspension spring. By adjusting the axial position of the spring bracket together with the nut, the vehicle height can be adjusted.

[0004] In addition, as another conventional suspension having a screw mechanism, an electromagnetic suspension is known (see Patent Document 2). In the electromagnetic suspension, the screw mechanism is used to convert the change in the distance between the body part and the wheel part of the vehicle into the rotational motion of the screw shaft. The screw is connected to a motor that hinders the rotation of the screw shaft. The damping force can be generated by the hindrance of the motor.

[0005] Prior Art Literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 8-276882

[0008] Patent Document 2: Japanese Patent Application Publication No. 2005-140144

[0009] However, in conventional actuators having a screw mechanism, there is a problem that the screw shaft needs to be lengthened to ensure the relative stroke of the nut with respect to the screw shaft, thereby increasing the overall length of the actuator. When the actuator has a small space for installation, it is desirable to shorten the overall length of the actuator.

[0010] The same problem also exists in the suspension with a screw mechanism in the past. That is, in the suspension with a screw mechanism in the past, there is the following problem: in order to ensure the relative stroke of the nut with respect to the screw shaft, the screw shaft needs to be lengthened, thereby the overall length of the suspension becomes longer. In the case where the configuration space of the actuator is small, it is desirable to shorten the overall length of the actuator. In the case where the configuration space of the suspension is small, it is desirable to shorten the overall length of the suspension. Summary of the invention

[0011] Problems to be solved by the invention

[0012] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a suspension that can shorten the overall length.

[0013] Solutions to Solve Problems

[0014] In order to solve the above-mentioned problems, one scheme of the present invention relates to a suspension, wherein the suspension comprises: a housing; a screw shaft, which is rotatably supported on the housing via a bearing; a nut, which is threadably engaged with the screw shaft; a shock absorber, which has a shell filled with working oil and an inner rod provided with a piston, and the shock absorber is configured to generate a damping force when the inner rod moves axially relative to the shell, the nut is connected to the inner rod of the shock absorber, and the screw shaft can enter the hollow portion of the inner rod.

[0015] Effects of the Invention

[0016] According to the present invention, the overall length of the suspension can be shortened. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 : is an external view of a suspension according to a first embodiment of the present invention in which an actuator according to a first embodiment of the present invention is assembled ( Figure 1 (a) is the side view, Figure 1 (b) is the main view).

[0018] Figure 2 It is a longitudinal sectional view of the suspension according to the present embodiment (the shortest state of the suspension).

[0019] Figure 3 yes Figure 2 Enlarged view of part III (longitudinal cross-sectional view of the actuator).

[0020] Figure 4 4 is a longitudinal sectional view of the suspension according to the present embodiment (the longest state of the suspension).

[0021] Figure 5 This is a detailed diagram of the anti-rotation mechanism ( Figure 4 (enlarged view of the V part).

[0022] Figure 6 It is a longitudinal sectional view of the suspension according to the second embodiment of the present invention in which the actuator according to the second embodiment of the present invention is assembled.

[0023] Description of reference numerals:

[0024] 1…suspension, 2…actuator, 3…drive unit, 6…impact absorber, 7…housing, 8…hollow shaft, 8b…bottom, 9a, 9b…bearings, 14…screw shaft, 15…nut, 21…inner rod, 21d…hollow portion, 32…protrusion, 33…stop member, 33a…limiter, 33b…groove, 41…suspension, 42…actuator, 43…motor, 44…housing. DETAILED DESCRIPTION

[0025] Hereinafter, the actuator and suspension of the embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the actuator and suspension of the present invention can be embodied in various forms and are not limited to the embodiment described in this specification. This embodiment is provided for the purpose of enabling those skilled in the art to fully understand the invention by making the specification fully disclosed.

[0026] (First embodiment)

[0027] Figure 1 This is an external view of a suspension 1 (vehicle height adjustment suspension) according to the first embodiment of the present invention in which the actuator 2 according to the first embodiment is incorporated. Figure 1 (a) is the side view, Figure 1 (b) is a main view. 2 is an actuator including a drive unit 3, 4 is a suspension spring, 5a and 5b are spring brackets, and 6 is an impact absorber. The suspension spring 4 and the impact absorber 6 absorb the unevenness of the road surface. The suspension spring 4 specifies the nominal vehicle height. The actuator 2 can be extended and retracted. The vehicle height is displaced up and down by the extension and retraction of the actuator 2.

[0028] The suspension 1 is provided between a portion on the vehicle body and a portion on the wheel side. The method of mounting the suspension 1 on the vehicle is not limited. The suspension 1 may be an independent suspension type suspension or an axle type suspension. For example, one end of the suspension 1 (one end of the housing 7) is connected to the vehicle body, and the other end of the suspension 1 (the other end of the impact absorber 6) is connected to the lower arm, or is connected to the lower arm via a push rod.

[0029] Figure 2 It is a longitudinal sectional view of the suspension 1 according to the present embodiment. Figure 3 yes Figure 2 The enlarged view of part III. Figure 3 As shown, the actuator 2 of this embodiment includes a housing 7, bearings 9a, 9b, a hollow shaft 8, a screw shaft 14, a nut 15, a drive unit 3, and a rotation stop mechanism 31 (see also Figure 2 ). Hereinafter, they will be described one by one.

[0030] The housing 7 is in the shape of a generally bottomed cylinder. The housing 7 is provided with a spherical bearing 7a for connection with a portion of the vehicle body. The hollow shaft 8 is rotatably supported on the housing 7 via bearings 9a and 9b. The hollow shaft 8 is in the shape of a generally bottomed cylinder having a smaller diameter than the housing 7. A flange 8a is formed on the hollow shaft 8. The position of the hollow shaft 8 in one axial direction (direction (1) in the figure) is determined by making the flange 8a abut against the bearing 9b. A worm wheel 12 is fixed to the flange 8a, and the worm wheel 12 meshes with the worm 11. Specifically, the annular worm wheel 12 is fixed to the flange 8a using a fixing scheme such as a stop ring or a serrated press fit.

[0031] The bearings 9a and 9b that support the hollow shaft 8 so that it can rotate are, for example, angular contact bearings. The bearing 9b is subjected to a load in one axial direction (the direction (1) in the figure applied by the weight of the vehicle body). The bearing 9a is subjected to a load in the other axial direction (the direction (2) in the figure when the vehicle body is lifted). The bearing 9b is larger than the bearing 9a. It should be noted that the type, number, and size of the bearings 9a and 9b are not limited to those described above, and thrust bearings may also be used for the bearings 9a and 9b.

[0032] The bottom 8b of the hollow shaft 8 is connected to a screw shaft 14, which has a common center line with the hollow shaft 8. An annular accommodation space S is formed between the hollow shaft 8 and the screw shaft 14 (see also Figure 4 ). The inner diameter of the hollow shaft 8 is larger than the outer diameter of the nut 15. The accommodation space S is formed so that the nut 15 can enter.

[0033] The screw shaft 14 is connected to the hollow shaft 8 in a non-rotatable and axially non-movable manner using a connection mechanism such as a key (not shown) and a fastening structure 17. The key is located between the hollow shaft 8 and the screw shaft 14, and the screw shaft 14 is connected to the hollow shaft 8 in a non-rotatable manner relative to the hollow shaft 8. The annular fastening structure 17 is screwed with the end of the screw shaft 14 and clamps the bearings 9a and 9b between the flange 8a of the hollow shaft 8. The fastening structure 17 prevents the screw shaft 14 from moving axially relative to the hollow shaft 8. A step 14b is formed on the screw shaft 14, and the step 14b abuts against the bottom 8b of the hollow shaft 8. It should be noted that the hollow shaft 8 and the screw shaft 14 can also be integrated so that they are one component.

[0034] An external thread 14a such as a trapezoidal thread is formed on the outer surface of the screw shaft 14. The nut 15 surrounding the screw shaft 14 is threadedly engaged with the screw shaft 14. An internal thread 15a such as a trapezoidal thread that is threadedly engaged with the external thread 14a is formed on the inner surface of the nut 15. It should be noted that threaded rollers evenly arranged along the circumferential direction can be inserted between the screw shaft 14 and the nut 15, or a plurality of balls can be interposed between the thread groove of the screw shaft 14 and the thread groove of the nut 15 in a manner that allows rolling motion.

[0035] A flange 15b is formed at one end of the nut 15. The nut 15 is connected to the inner rod 21 of the shock absorber 6 via the flange 15b using a connection mechanism such as a bolt. A flange 21a is also formed at one end of the inner rod 21 of the shock absorber 6. The spring bracket 5a is fixed to the flange 21a of the inner rod 21. A gasket (not shown) is attached to the flange 21a of the inner rod 21 to prevent the flange 21a from contacting the housing 7.

[0036] like Figure 2 As shown, the drive unit 3 includes a motor 19 and a gear device 13. Figure 1 As shown, a gear box 7b for accommodating the gear device 13 is formed in the housing 7. The motor 19 is mounted on the gear box 7b. The center line of the motor 19 is at right angles to the center line of the screw shaft 14 of the actuator 2. Figure 2 As shown, the gear device 13 includes a worm 11 and a worm wheel 12. The worm 11 is connected to the output shaft of the motor 19. The worm wheel 12 meshes with the worm 11. As described above, the worm wheel 12 is provided on the flange 8a of the hollow shaft 8.

[0037] When the driving motor 19 rotates, the hollow shaft 8 is rotated via the gear device 13. When the hollow shaft 8 rotates, the screw shaft 14 rotates together with the hollow shaft 8. The nut 15 is stopped by the rotation stop mechanism 31, so the nut 15 moves in the axial direction.

[0038] The anti-rotation mechanism 31 includes a protrusion 32 and an anti-rotation member 33. Figure 5 As shown, a protrusion 32 is fixed to the outer surface of the housing 7. The protrusion 32 is, for example, semi-cylindrical. The anti-rotation member 33 faces the outer surface of the housing 7. Figure 2 As shown, the rotation-stopping member 33 is fastened to the nut 15 via the flange 21 a of the inner rod 21 using a fastening mechanism such as a bolt.

[0039] like Figure 5 As shown, the anti-rotation member 33 includes a frame-shaped guide limiter 34 and a guide rail 35 embedded in the guide limiter 34. A groove 33b is formed in the guide rail 35, and the groove 33b is embedded in the protrusion 32 and extends in the axial direction. The groove 33b is semicircular in cross section. A limiter 33a is provided at the front end of the guide limiter 34, and the limiter 33a can abut against the protrusion 32. The groove 35a formed on the side of the guide rail 35 is embedded in the protrusion 34a formed on the inner side surface of the guide limiter 34, and the guide limiter 34 is connected to the flange 21a of the inner rod 21 using a connecting mechanism such as a bolt. It should be noted that the guide limiter 34 and the guide rail 35 can also be integrated so that they are one component.

[0040] like Figure 2 As shown, the suspension 1 of the present embodiment includes an actuator 2, a suspension spring 4, and a shock absorber 6. The suspension spring 4 and the shock absorber 6 will be described in order below.

[0041] The suspension spring 4 is a coil spring that is concentric with the shock absorber 6. The suspension spring 4 is interposed between a spring bracket 5a and a spring bracket 5b. The spring bracket 5a is fitted in a nut 15. The spring bracket 5b is fixed to the shock absorber 6.

[0042] The shock absorber 6 includes an inner rod 21 and a housing 22. The spring bracket 5b is fixed to the housing 22. A connecting member 23 is fixed to an end of the housing 22, and the connecting member 23 is provided with a spherical bearing 23a.

[0043] The housing 22 is filled with hydraulic oil. A piston 21b is provided at the end of the inner rod 21. The interior of the housing 22 is divided into two working chambers by the piston 21b. A damping hole 21c is formed in the piston 21b. The shock absorber 6 is configured to generate a damping force when the inner rod 21 moves axially relative to the housing 22.

[0044] A hollow portion 21d is formed at one end of the inner rod 21 (see also Figure 3 ). The hollow portion 21d is composed of a hole extending in the axial direction. The inner diameter of the hollow portion 21d is larger than the outer diameter of the screw shaft 14. The hollow portion 21d is formed so that the screw shaft 14 can enter.

[0045] The above describes the structure of the actuator 2 and the suspension 1 of the present embodiment. According to the actuator 2 and the suspension 1 of the present embodiment, the following functions and effects are achieved. When the drive unit 3 drives the screw shaft 14 to rotate, the nut 15, which is stopped by the rotation stop mechanism 31, moves along the axial direction of the screw shaft 14. The nut 15 is engaged with the spring bracket 5a, so that the spring bracket 5a moves relative to the housing 7 along the axial direction of the screw shaft 14. Therefore, the actuator 2 (suspension 1) is Figure 2 The shortest state shown is Figure 4 Telescoping between the longest states shown.

[0046] exist Figure 2 In the shortest state of the actuator 2 (suspension 1) shown, the nut 15 enters between the hollow shaft 8 and the screw shaft 14, and the nut 15 overlaps with the bearing 9b (i.e., the nut 15 overlaps with the bearing 9b in a side view). In addition, the screw shaft 14 enters the hollow portion 21d of the inner rod 21. Moreover, the stop member 33 overlaps with the bearings 9a and 9b (i.e., the stop member 33 overlaps with the bearings 9a and 9b in a side view). Therefore, the overall length of the actuator 2 can be shortened while ensuring the stroke of the nut 15, and the overall length of the suspension 1 can be shortened.

[0047] In the conventional actuator and suspension, the bearing, nut, and inner rod are not arranged in an overlapping manner. Therefore, in order to ensure the stroke of the nut, the overall length of the actuator and the suspension needs to be lengthened. According to the suspension 1 of this embodiment, the overall length of the actuator 2 and the suspension 1 can be shortened while ensuring the stroke of the nut 15.

[0048] exist Figure 4 In the longest state of the actuator 2 (suspension 1 ) shown, the stopper 33 a of the rotation-stopping member 33 abuts against the protrusion 32 to restrict the relative movement of the nut 15 in the axial direction with respect to the housing 7 . Therefore, the nut 15 can be prevented from coming off the screw shaft 14 .

[0049] In the conventional actuator and suspension, in order to prevent the nut from falling off the screw shaft, a stopper is required to be provided at the terminal of the screw shaft. According to the actuator 2 and suspension 1 of this embodiment, a stopper 33a is provided on the rotation stop member 33, so that the nut 15 can be easily prevented from falling off the screw shaft 14.

[0050] (Second embodiment)

[0051] Figure 6 4 is a longitudinal sectional view of a suspension 41 (electromagnetic suspension) according to a second embodiment of the present invention in which an actuator 42 according to a second embodiment of the present invention is assembled. Reference numeral 42 denotes an actuator including a motor 43, reference numeral 4 denotes a suspension spring, and reference numeral 6 denotes a shock absorber.

[0052] The structures of the suspension spring 4 and the shock absorber 6 are substantially the same as those of the suspension 1 of the first embodiment, and thus the same reference numerals are used to mark them and their description is omitted. The structures of the hollow shaft 8, the screw shaft 14, the nut 15, the bearings 9a, 9b, and the anti-rotation mechanism 31 of the actuator 42 are also substantially the same as those of the suspension 1 of the first embodiment, and thus the same reference numerals are used to mark them and their description is omitted.

[0053] In the suspension 41 of the second embodiment, the housing 44 of the actuator 42 is elastically attached to the vehicle body. The screw shaft 14 penetrates the housing 44 and the vehicle body. The motor 43 is connected to one end of the screw shaft 14.

[0054] The screw mechanism of the actuator 42 uses a ball screw to improve reverse efficiency. That is, a plurality of balls 45 are interposed between the thread groove of the screw shaft 14 and the thread groove of the nut 15 in a rollable manner.

[0055] When the distance between the part on the vehicle body and the part on the wheel side changes, the nut 15 moves up and down (the nut 15 moves along the axial direction of the screw shaft 14). The axial movement of the nut 15 is converted into the rotational movement of the screw shaft 14 by the screw mechanism. When the screw shaft 14 rotates, the motor 43 generates electricity. The resistance when the motor 43 generates electricity can cause the suspension 41 to generate a damping force. It should be noted that the impact absorber 6 absorbs high-frequency vibrations input from the road surface, making it difficult for the high-frequency vibrations to be transmitted to the nut 15.

[0056] On the other hand, when the motor 43 is rotated by the battery power, the nut 15 is displaced up and down, and the inner rod 21 of the impact absorber 6 is displaced up and down together with the nut 15. The propulsion force of the inner rod 21 is transmitted to the part on the wheel side in a state where it is absorbed to a certain extent by the impact absorber 6. In this way, the damping force of the suspension 41 can be adjusted.

[0057] The suspension 41 of the second embodiment also exhibits substantially the same effects as those of the suspension 1 of the first embodiment, and thus detailed description thereof will be omitted.

[0058] It should be noted that the present invention is not limited to the embodiments embodied in the above-mentioned embodiments, and can be modified into other embodiments within the scope of the gist of the present invention.

[0059] In the above embodiment, an example in which the actuator is assembled to the suspension is described, but the actuator is not limited to being assembled to the suspension. For example, the actuator can be used as a telescopic actuator or as an X-axis actuator that moves the movable part along the X-axis direction.

[0060] This specification is based on Japanese Patent Application No. 2019-208426 filed on November 19, 2019. The entire contents are incorporated herein.

Claims

1. A suspension, wherein: The suspension comprises: shell; a screw shaft rotatably supported by the housing via a bearing; a nut, which is threadably engaged with the screw shaft; and A shock absorber having a housing filled with hydraulic oil and an inner rod provided with a piston, wherein the shock absorber is configured to generate a damping force when the inner rod moves in an axial direction relative to the housing, The nut is connected to the inner rod of the impact absorber, The screw shaft can enter the hollow portion of the inner rod.

2. The suspension according to claim 1, characterized in that The screw shaft is driven to rotate by a driving unit, so that the nut is relatively moved along the axial direction with respect to the screw shaft to adjust the vehicle height.

3. The suspension according to claim 1, characterized in that The screw shaft is connected to a motor for generating a damping force.

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