LINEAR MOTION DEVICE, CONVERSION MECHANISM, CONSTRUCTION MACHINE AND RAILWAY BRAKE

Abstract

[Task] A shock is damped, which is transmitted to a linear motion mechanism 5, which converts a rotary motion into a linear motion. [Solution] A linear motion device 1 includes a drive unit 2 that outputs rotation, a linear motion mechanism 5 that converts rotational motion input from the drive unit 2 into linear motion, a cylinder 6 that accommodates a fluid L into which the linear motion is input from the linear motion mechanism 5, and an output member 7 to which the linear motion input from the linear motion mechanism 5 is transmitted via the fluid L.

Description

Technical area

[0001] The present invention relates to a linear motion device, a conversion mechanism, a construction machine, and a railway brake. Background technology

[0002] A device that converts the rotary motion output from an electric mechanism into a linear motion and utilizes it is conventionally known. For example, Patent Document 1 describes an electric linear actuator for generating a driving force of a linear motion drive section in a construction machine such as an excavator. Specifically, Patent Document 1 describes that the electric linear actuator is used to drive a boom, arm, bucket, or the like of the excavator.

[0003] The electric linear actuator described in Patent Document 1 includes both an electric mechanism including a rotary shaft and a feed screw device including a feed screw shaft and a linear motion nut. The feed screw device is configured such that when the feed screw shaft is rotated by the electric mechanism, the linear motion nut engaging with the feed screw shaft is moved linearly. The electric linear actuator described in Patent Document 1 converts rotary motion into linear motion with the aid of the feed screw device. Citation listPatent document

[0004] Patent Document 1: International Publication No. WO 2013 / 114451 Disclosure of the invention

[0005] A shock could be transmitted from the side where a linear motion is output to a mechanism that converts rotary motion into linear motion, such as the conveyor screw device described in Patent Document 1. In particular, in the case where the mechanism was used to drive a construction equipment, such as a boom, arm, bucket, or the like of an excavator, a relatively strong shock could be transmitted to the mechanism. It was also suspected that by transmitting the strong shock to the mechanism that converts rotary motion into linear motion, the mechanism was damaged. For this reason, it was necessary to dampen the shock transmitted to the mechanism that converts rotary motion into linear motion.

[0006] The present invention has been made in consideration of the above circumstances, and the object of the present invention is to dampen a shock transmitted to a linear motion mechanism that converts a rotational motion into a linear motion.

[0007] A first aspect of the present disclosure relates to a linear motion device comprising: a drive unit that outputs rotation; a linear motion mechanism that converts a rotary motion input from the drive unit into a linear motion; a cylinder that accommodates a fluid into which the linear motion from the linear motion mechanism is input; and an output element to which the linear motion input from the linear motion mechanism is transmitted via the fluid.

[0008] According to a second aspect of the present disclosure, in the linear motion device according to the above-described first aspect, the drive unit may include an electric mechanism and a reduction section that decelerates rotation of the electric mechanism and transmits it to the linear motion mechanism.

[0009] According to a third aspect of the present disclosure, in the linear motion device according to the above-described first aspect or the above-described second aspect, an area of ​​a surface that presses the fluid of the linear motion mechanism and an area of ​​a surface that is pressed by the fluid of the output member may be different from each other.

[0010] According to a fourth aspect of the present disclosure, in the linear motion device according to the above-described third aspect, the area of ​​the surface that presses the fluid of the linear motion mechanism may be larger than the area of ​​the surface that is pressed by the fluid of the output member.

[0011] According to a fifth aspect of the present disclosure, in the linear motion device according to any one of the first to fourth aspects described above, the cylinder may have a tubular shape, the linear motion mechanism may have a surface that pushes the fluid, the output element may have a surface which is pressed by the fluid, and the fluid may be enclosed in a space surrounded by an inner surface of the cylinder, the surface that pushes the fluid, of the linear motion mechanism, and the surface that is pushed by the fluid, of the output element.

[0012] According to a sixth aspect of the present disclosure, the linear motion device according to the above-described fifth aspect may further include an accumulator having a first chamber opened on the inner surface of the cylinder so as to communicate with the space, and a second chamber whose volume changes depending on a pressure in the first chamber to change a volume of the first chamber.

[0013] According to a seventh aspect of the present disclosure, the linear motion device according to any of the first to sixth aspects described above may further comprise: a receiving member that receives at least one rotary unit, which rotates by a rotary motion input from the drive unit, of the linear motion mechanism; and a bearing in contact with the rotating unit and the receiving element such that the rotating unit can rotate relative to the receiving element.

[0014] According to an eighth aspect of the present disclosure, in the linear motion device according to the second aspect described above, the reducing section may include: a first element having internal teeth; a second member relatively rotatable relative to the first member; a crankshaft rotatably supported on the second member; and an external gear provided with a through-hole through which the crankshaft passes and having external teeth which engage with the internal teeth of the first element, wherein rotation of the second member can be input into the linear motion mechanism.

[0015] According to a ninth aspect of the present disclosure, in the linear motion device according to any one of the first to eighth aspects described above, the linear motion mechanism may include a ball screw including a screw shaft and a nut.

[0016] A tenth aspect of the present disclosure relates to a conversion mechanism that converts rotary motion into linear motion, comprising: a linear motion mechanism that converts an input rotary motion into a linear motion; a cylinder that accommodates a fluid into which the linear motion from the linear motion mechanism is input; and an output element to which the linear motion input from the linear motion mechanism is transmitted via the fluid.

[0017] An eleventh aspect of the present disclosure relates to a construction machine comprising: the linear motion device according to each of the first to ninth aspects described above; and an action section which is linearly driven by the linear motion device.

[0018] A twelfth aspect of the present disclosure relates to a railway brake comprising the linear motion device according to any one of the first to ninth aspects described above.

[0019] According to the present invention, a shock transmitted to a linear motion mechanism that converts a rotary motion into a linear motion can be damped. Brief explanation of the figures [ Fig. 1] Fig. 1 shows a cross-sectional view of a configuration example of a linear motion device according to an embodiment. [ Fig. 2] Fig. 2 shows a cross-sectional view of a reduction portion according to the embodiment. [ Fig. 3] Fig. 3 shows a cross-sectional view of the reduction portion according to the embodiment. [ Fig. 4] Fig. 4 is a cross-sectional view showing a configuration example of the linear motion device according to a modification 1. [ Fig. 5] Fig. 5 is a cross-sectional view showing a configuration example of the linear motion device according to a modification 2. [ Fig. 6] Fig. 6 is a cross-sectional view showing a configuration example of the linear motion device according to a modification 3. [ Fig. 7] Fig. 7 is a cross-sectional view showing a configuration example of the linear motion device according to a modification 4. [ Fig. 8] Fig. 8 is a cross-sectional view showing a configuration example of the linear motion device according to Modification 4. Forms for carrying out the invention

[0020] The present embodiment will be described in detail with reference to drawings. First, a linear motion device 1 according to the present embodiment will be described. Fig. 1 shows a cross-sectional view of a configuration example of the linear motion device 1. Fig. 1 shows in particular a cross-sectional view of the linear motion device 1, cut in a plane passing through a rotation axis LA of a rotation output by a drive unit 2 described below.

[0021] The linear motion device 1 includes the drive unit 2 that outputs rotation, a linear motion mechanism 5, a cylinder 6, and an output member 7. The linear motion mechanism 5 converts rotational motion input from the drive unit 2 into linear motion. The cylinder 6 accommodates a fluid L into which the linear motion from the linear motion mechanism 5 is input. The linear motion input from the linear motion mechanism 5 is transmitted to the output member 7 via the fluid L. A direction in which the axis LA extends is referred to as an axis direction DA. A side of the axis direction DA on which the output member 7 is located, with the linear motion mechanism 5 serving as a reference, is referred to as a first side SA1. A side of the axis direction DA on which the linear motion mechanism 5 is located, with the output member 7 serving as a reference, is referred to as a second side SA2.A direction that revolves around the axis LA is called the circumferential direction DB, and a direction perpendicular to the axis LA is called the radial direction DC.

[0022] The drive unit 2 will be described in more detail. The drive unit 2 includes an electric mechanism 3 and a reduction section 4, which slows down rotation of the electric mechanism 3 and transmits it to the linear motion mechanism 5.

[0023] In the present embodiment, the electric mechanism 3 is a general electric motor. Fig. 1, the electrical mechanism 3 is attached to a mounting element 47 of the reduction section 4 described below. Although not shown, the electrical mechanism 3 is screwed to the mounting element 47 by means of a bolt and thus fastened to the surface of the mounting element 47 located on the second side SA2. The mounting element 47 is, as shown in Fig. 1, is provided with a through-hole 471 that passes through the mounting member 47 in the axial direction DA. A rotary shaft 31 of the electric mechanism 3 is inserted into the through-hole 471. The rotary shaft 31 projects toward the first side SA1 and extends in the axial direction DA. Fig. 1, the axis of rotation about which the rotary shaft 31 rotates coincides with the axis of rotation LA of a rotation output by the drive unit 2.

[0024] The reduction section 4 will be described. The reduction section 4 is arranged on the first side SA1 of the axis direction DA of the electric mechanism 3.

[0025] Fig. Figure 2 shows a cross-sectional view of the reduction section 4, cut in a plane passing through the axis LA. It should be noted that in Fig. 2, a representation of the mounting element 47 is omitted. Fig. Figure 3 shows a cross-sectional view of the reduction section 4, cut along the line III-III in Fig. 2. The reduction section 4 includes a first element 41, a second element 42 that is relatively rotatable relative to the first element 41, and a reduction mechanism 45 that decelerates an input from the electric mechanism 3 to rotate the first element 41 and the second element 42 relative to each other. Rotation of the second element 42 of the reduction section 4 is input to the linear motion mechanism 5.

[0026] In the present embodiment, the first member 41 has internal teeth 412. The reduction mechanism 45 includes crankshafts 43 rotatably supported on the second member 42, and external gears 44 provided with through-holes 44d through which the respective crankshafts 43 pass, and having external teeth 441a and 442a. In the reduction mechanism 45, the crankshafts 43, to which rotation is input, cause eccentric vibration of the external gears 44. When the external teeth 441a and 442a of the external gears 44, which are subjected to eccentric vibration, mesh with the internal teeth 412 of the first member 41, the first member 41 and the second member 42 rotate relative to each other.

[0027] In the present embodiment, the external gear 44 is provided with the through holes 44d through which the respective crankshafts 43 pass. That is, the reduction section 4 of the present embodiment includes the first member 41 having the internal teeth 412, the second member 42 relatively rotatable relative to the first member 41, the crankshafts 43 rotatably supported on the second member 42, and the external gears 44 provided with the through holes 44d through which the respective crankshafts 43 pass and having external teeth 441a and 442a that mesh with the internal teeth 412 of the first member 41. Rotation of the second member 42 is input to the linear motion mechanism 5. In this case, the reduction section 4 can be said to include the crankshafts 43 and the external gears 44 as the reduction mechanism 45.

[0028] In the present embodiment, the reduction mechanism 45 includes the plurality of crankshafts 43. The plurality of crankshafts 43 extend through the through holes 44d of the external gear 44. The external gear 44 is provided with the plurality of through holes 44d, and the plurality of crankshafts 43 extend through the respective through holes 44d.

[0029] In the present embodiment, the reduction section 4 includes a cylindrical housing 41a as the first member 41. As the second member 42, the reduction section 4 further includes a bracket 42a disposed inward in the radial direction DC of the housing 41a (on the side approaching the axis LA in the radial direction DC). The reduction section 4 further includes an input shaft 46 that provides a driving force for rotating the bracket 42a. The reduction section 4 further includes the mounting member 47 provided with the through-hole 471 and to which the electric mechanism 3 is fixed. The mounting member 47 has a cylindrical shape. The reduction section 4 further includes a third member 48 fixed to the first member 41 (the housing 41a). The third member 48 has a cylindrical shape. The third element 48 is located on the first side SA1 of the axial direction DA of the housing 41a.A part in the vicinity of the end portion of the housing 41a located outside in the radial direction DC (on the side away from the axis LA in the radial direction DC) is held clamped in the axial direction DA between the third member 48 and the mounting member 47.

[0030] A screw hole 41b extending in the axial direction DA and opening on the second side SA2 is provided in the vicinity of the end portion of the housing 41a located outward in the radial direction DC (on the side away from the axis LA in the radial direction DC). Using the screw hole 41b, the mounting member 47 is screwed to the housing 41a by means of a bolt, thus fixing the mounting member 47 to the housing 41a. By fixing the mounting member 47 to the housing 41a and fixing the electrical mechanism 3 to the mounting member 47, the electrical mechanism 3 is fixed to the housing 41a via the mounting member 47. A through hole 41c extending in the axial direction DA and penetrating the housing 41a is provided in the vicinity of the end portion of the housing 41a located outward in the radial direction DC.The third member 48 is provided with a screw hole 48a extending in the axial direction DA and open on the second side SA2. Using the screw hole 48a and the through-hole 41c, the mounting member 47 and the third member 48 can be screwed to the housing 41a by means of a bolt. Specifically, when the bolt is inserted into the through-hole of the mounting member 47 and the through-hole 41c of the housing 41a (in . Fig. 3 not shown) is inserted into the screw hole 48a of the third element 48, the mounting element 47 and the third element 48 are screwed to the housing 41a.

[0031] The internal teeth 412 are arranged on the inner peripheral surface of the housing 41a. The internal teeth 412 are pin-shaped (round column-shaped) teeth arranged on the inner peripheral surface of the housing 41a. Specifically, the first member 41 includes internal tooth pins 412a, which are inserted into pin grooves 412b. A plurality of internal teeth 412 are arranged at equal intervals in the radial direction DC.

[0032] The carrier 42a is rotatably mounted on the housing 41a by paired main bearings 42j, which are spaced apart in the axial direction DA. The main bearings 42j are, for example, angular contact ball bearings. The carrier 42a is arranged coaxially with the housing 41a and the axis LA.

[0033] The carrier 42a comprises a disc-shaped end plate portion 421 arranged on the second side SA2 of the axial direction DA, a disc-shaped substrate portion 422 arranged on the first side SA1 of the axial direction DA, and three column portions 423 formed integrally with the substrate portion 422 and projecting from the substrate portion 422 toward the end plate portion 421. The Fig. The column sections 423 shown in Figure 3 each have a columnar shape, with its cross section perpendicular to the axial direction DA having a substantially triangular shape with rounded corners. The column sections 423 are arranged at equal intervals in the circumferential direction DB. The column sections 423 and the end plate section 421 are screwed together by means of a bolt 42b in a state in which the front end surfaces of the column sections 423 overlap with the end plate section 421, and are thereby fixed to each other. In this state, a space having a predetermined width in the axial direction is formed between the substrate section 422 and the end plate section 421.

[0034] A bolt screw hole 42c is formed in the column portion 423, into which the bolt 42b is screwed. A bolt insertion hole 42d is formed in the end plate portion 421, into which the bolt 42b is inserted. The bolt 42b, inserted into the bolt insertion hole 42d from the side opposite the column portion 423 with the end plate portion 421 therebetween, is screwed into the bolt screw hole 42c of the column portion 423. A pin 42e for positioning the end plate portion 421 relative to the substrate portion 422 is arranged further inward in the radial direction than the bolt 42b. The pin 42e is arranged to straddle the column portions 423 and the end plate portion 421. It should be noted that the column sections 423 do not necessarily have to be formed integrally with the substrate section 422.In this case, the column sections 423 are screwed to the substrate section 422. Furthermore, the column sections 423 do not necessarily have to have a columnar shape; their cross-section perpendicular to the axis direction DA may be substantially triangular with rounded corners. It is sufficient if a space having a predetermined width in the axis direction DA is formed between the substrate section 422 and the end plate section 421 by the column sections 423. Alternatively, the column sections 423 may be round-columnar.

[0035] In the end plate portion 421 and the substrate portion 422, a plurality of hole portions 42f and 42g (e.g., three each in the present embodiment) are formed, into which the respective crankshafts 43 of the reduction mechanism 45 are inserted. The hole portions 42f and 42g are arranged at equal intervals in the circumferential direction. Further, at the center of the end plate portion 421 and the substrate portion 422 in the radial direction DC, a through hole 42h and a through hole 42i are formed, respectively, which pass through in the axial direction DA. The input shaft 46 is arranged coaxially with the housing 41a and the axis LA.

[0036] A proximal end portion of the input shaft 46 on the side of the electric mechanism 3 (on the second side SA2 of the axis direction DA) is coupled to the rotating shaft 31 of the electric mechanism 3. As a result, the input shaft 46 rotates together with the rotating shaft 31. A front end portion 46a of the input shaft 46 on the side opposite the electric mechanism 3 (on the first side SA1 of the axis direction DA) is arranged inside the mounting member 47. A drive gear 461 having external teeth is provided integrally with the front end portion 46a of the input shaft 46. In the Fig. 2, a screw shaft 54 ​​of the linear motion mechanism 5 described below is inserted into the through-hole 42i of the substrate portion 422, a first through-hole 44a of a first external gear 441 and a second external gear 442, and the through-hole 42h of the end plate portion 421. In the example shown in Fig. In the example shown in Figure 1, the end portion of the screw shaft 54 ​​located on the second side SA2 of the axis direction DA is disposed inside the mounting member 47. In this way, in the present embodiment, the screw shaft 54 ​​of the linear motion mechanism 5 can penetrate into the through-hole 42i of the substrate portion 422, the first through-hole 44a of the first external gear 441 and the second external gear 442, the through-hole 42h of the end plate portion 421, and the interior of the mounting member 47. This ensures the width of the space within which the screw shaft 54 ​​can move linearly.

[0037] The reduction mechanism 45 rotates the carrier 42a at a speed reduced by a predetermined ratio from the speed of the input shaft 46. The reduction mechanism 45 includes a plurality of (e.g., three in the present embodiment) transmission gears 431 meshing with the drive gear 461, and a plurality of (e.g., three in the present embodiment) crankshafts 43, one end of which is fixed to the respective transmission gears 431. In the present embodiment, the reduction mechanism 45 further includes the first external gear 441 and the second external gear 442, which rotate oscillatingly with the rotation of the crankshafts 43, as external gears 44.

[0038] The transmission gears 431 are fixed to one end of the crankshafts 43; therefore, rotation of the rotary shaft 31 is transmitted to the crankshafts 43 via the transmission gears 431. The crankshafts 43 are arranged parallel to the input shaft 46. That is, the crankshafts 43 rotate about the rotation axis parallel to the rotation axis LA of a rotation output from the drive unit 2. The crankshaft 43 is rotatably supported on the end plate portion 421 via a first crank bearing 43a. The crankshaft 43 is further rotatably supported on the substrate portion 422 via a second crank bearing 43b. The first crank bearing 43a and the second crank bearing 43b are, for example, tapered roller bearings.

[0039] At the axial center of the crankshaft 43, a first eccentric portion 43c and a second eccentric portion 43d are formed, which are eccentric with respect to the shaft center of the crankshaft 43. The first eccentric portion 43c and the second eccentric portion 43d are disposed adjacent to each other between the first crank bearing 43a and the second crank bearing 43b in the axial direction DA. The first eccentric portion 43c is adjacent to the first crank bearing 43a. The second eccentric portion 43d is adjacent to the second crank bearing 43b. The phase angle of the first eccentric portion 43c and that of the second eccentric portion 43d differ from each other.

[0040] These crankshafts 43 are inserted into the respective hole portions 42f and the respective hole portions 42g of the end plate portion 421 and the substrate portion 422, respectively. That is, the crankshafts 43, like the hole portions 42f and the hole portions 42g, are arranged at equal intervals in the circumferential direction DB.

[0041] A first roller bearing 43e is mounted on the first eccentric portion 43c of the crankshaft 43. A second roller bearing 43f is mounted on the second eccentric portion 43d. The first roller bearing 43e is, for example, a cylindrical roller bearing. Via the roller bearings 43e and 43f, the first external gear 441 and the second external gear 442 oscillate with the rotation of the crankshafts 43.

[0042] The first external gear 441 and the second external gear 442 are arranged in a space between the substrate portion 422 and the end plate portion 421 of the carrier 42a. The first external gear 441 and the second external gear 442 have external teeth 441a and 442a, respectively, which mesh with the internal teeth 412 of the housing 41a. The first external gear 441 and the second external gear 442 are formed with the first through-hole 44a arranged around the axis LA, second through-holes 44b into which the respective column portions 423 are inserted, and through-holes 44d into which the respective crankshafts 43 are inserted. The eccentric portions 43c and 43d of the crankshaft 43 are inserted into the through-hole 44d.

[0043] The first eccentric portion 43c and the first roller bearing 43e of the crankshaft 43 are inserted into the through-hole 44d of the first external gear 441. The second eccentric portion 43d and the second roller bearing 43f of the crankshaft 43 are inserted into the through-hole 44d of the second external gear 442. As a result, the first eccentric portion 43c and the second eccentric portion 43d swingably rotate due to rotation of the crankshafts 43, and thus the first external gear 441 and the second external gear 442 swingably rotate while meshing with the internal teeth 412 of the housing 41a.

[0044] The action of the reduction section 4 is described. When the electric mechanism 3 is driven, the input shaft 46 is driven together with the rotating shaft 31. The rotation of the input shaft 46 then causes the transmission gears 431 to rotate via the drive gear 461. As a result, the crankshafts 43 rotate together with the transmission gears 431.

[0045] When the crankshaft 43 rotates, the first external gear 441 rotates with the momentum of the first eccentric portion 43c while meshing with the internal teeth 412. Furthermore, the second external gear 442 rotates with the momentum of the second eccentric portion 43d while meshing with the internal teeth 412. That is, the crankshafts 43 rotate around the rotation axis parallel to the rotation axis LA of a rotation output from the drive unit 2 and orbit the rotation axis LA. Thus, the rotation of the crankshafts 43 drives the first external gear 441 and the second external gear 442.

[0046] When the first external gear 441 and the second external gear 442 are driven, the second member 42 (the carrier 42a), in which the column portions 423 are inserted into the first external gear 441 and the second external gear 442, is driven by the first external gear 441 and the second external gear 442. As a result, the carrier 42a rotates relative to the housing 41a, which is fixed to the electric mechanism 3 via the mounting member 47, at a speed reduced from the speed of the input shaft 46. Consequently, rotation of the electric mechanism 3 can be slowed down by the reduction portion 4.

[0047] It should be noted that, as the reduction section 4, the reduction section 4 in which the reduction mechanism 45 includes the crankshafts 43 and the external gears 44 is specifically described; however, the shape of the reduction section 4 is not limited thereto. It is also possible that the reduction mechanism 45 of the reduction section 4 includes a planetary gear rotatably supported on the second member 42, and the planetary gear, to which rotation is input, meshes with the internal teeth 412 of the first member 41 to rotate the first member 41 and the second member 42 relative to each other. That is, the reduction section 4 may alternatively be a planetary gear reduction gear.

[0048] The linear motion mechanism 5 will be described. The linear motion mechanism 5 converts a rotary motion input from the drive unit 2 into a linear motion. The linear motion mechanism 5 is arranged on the first side SA1 of the axial direction DA of the reduction section 4. The linear motion mechanism 5 includes a rotary unit 51 that rotates by a rotary motion input from the drive unit 2, and a linear motion unit 52 that is driven by the rotary motion of the rotary unit 51 and moves linearly. The rotary unit 51 is fixed to a rotating part of the drive unit 2 and rotates with the rotation of the rotating part. Rotation of the linear motion unit 52 relative to the cylinder 6 in the circumferential direction DB is inhibited. In the present embodiment, the rotary unit 51 is fixed to the second member 42 (the bracket 42a) of the reduction section 4.The rotating unit 51 is, in particular, attached to the second element 42 via the third element 48. As a result, rotation of the second element 42 (the carrier 42a), which rotates at a speed reduced compared to the speed of the input shaft 46, is input to the rotating unit 51.

[0049] In the present embodiment, the linear motion mechanism 5 includes a ball screw 53 including the screw shaft 54 ​​and a nut 55. The nut 55 of the ball screw 53 is fixed to the second member 42. The nut 55 is fixed to the end portion of the second member 42 located on the first side SA1 of the axis direction DA. In the present embodiment, the nut 55 constitutes the rotary unit 51, which rotates by a rotary motion input from the drive unit 2. Further, in the present embodiment, the screw shaft 54 ​​constitutes the linear motion unit 52, which is driven by a rotary motion of the rotary unit 51 and moves linearly.

[0050] The nut 55 is a member provided with a through-hole 55b in which an internal thread 55a is formed. The internal thread 55a is provided on the inner wall of the through-hole 55b. In the present embodiment, the through-hole 55b extends in the axis direction DA. The through-hole 55b is arranged such that the axis LA is at the center of the through-hole 55b.

[0051] The screw shaft 54 ​​is a rod-shaped element with an external thread 54a formed therein. In the present embodiment, the external thread 54a extends in the axial direction DA. The screw shaft 54 ​​is arranged coaxially with the axis LA.

[0052] The external thread 54a of the screw shaft 54 ​​and the internal thread 55a of the nut 55 are engaged with each other. Therefore, when one of the screw shaft 54 ​​and the nut 55 rotates relative to the other in the circumferential direction DB, the positional relationship between the screw shaft 54 ​​and the nut 55 changes in the axial direction DA.

[0053] In the present embodiment, the nut 55 rotates by a rotational motion input from the drive unit 2, and the screw shaft 54 ​​is then driven by the rotational motion of the nut 55 and moves linearly. By using the ball screw 53, which includes the screw shaft 54 ​​and the nut 55, for the linear motion mechanism 5 in this way, rotational motion can be converted into linear motion. In the case where the linear motion mechanism 5 includes the ball screw 53, the linear motion unit 52 moves linearly in the direction in which the through hole 55b and the screw shaft 54 ​​extend. In the present embodiment, the linear motion unit 52 moves linearly in the axis direction DA.

[0054] The linear motion mechanism 5 has a surface 56 that pushes the fluid L accommodated in the cylinder 6 described below. The surface 56 that pushes the fluid L of the linear motion mechanism 5 is also referred to as a pushing surface 56. The pushing surface 56 is a surface that pushes the fluid L when linear motion is input to the fluid L. In the present embodiment, the linear motion unit 52 of the linear motion mechanism 5 has the pushing surface 56. In the present embodiment, the pushing surface 56 is a surface perpendicular to the direction in which the linear motion unit 52 linearly moves (the axis direction DA).In the present embodiment, the screw shaft 54 ​​constituting the linear motion unit 52 includes a screw shaft body 54b in which the external thread 54a is formed, and a pressing portion 54c provided at the end portion of the screw shaft body 54b located on the first side SA1 of the axial direction DA. The pressing portion 54c has a larger dimension in the radial direction DC than the screw shaft body 54b. In the present embodiment, the surface of the pressing portion 54c located on the first side SA1 of the axial direction DA forms the pressing surface 56.

[0055] The cylinder 6 will be described. The cylinder 6 is a member that accommodates the fluid L, to which linear motion is input from the linear motion mechanism 5. In the present embodiment, the cylinder 6 has a tubular shape. The cylinder 6 is arranged on the first side SA1 of the axis direction DA of the linear motion mechanism 5.

[0056] The cylinder 6 houses the portion of the linear motion mechanism 5 having the pressing surface 56. In the present embodiment, the cylinder 6 houses the pressing portion 54c of the screw shaft 54. In the present embodiment, a part of the linear motion unit 52 penetrates into the interior of the cylinder 6 via an opening of the tubular cylinder 6 located on the first side SA1 of the axis direction DA. In this way, the cylinder 6 houses the portion of the linear motion mechanism 5 having the pressing surface 56. Further, in the portion housing the portion of the linear motion mechanism 5 having the pressing surface 56, the cylinder 6 extends in the direction of a linear motion output from the linear motion mechanism 5.In the present embodiment, the cylinder 6 includes a portion in which a hollow portion is formed, which has the same shape as the pressing surface 56 in the cross section perpendicular to the direction in which the linear motion unit 52 moves linearly (the axis direction DA). This portion is referred to as the first portion 61 of the cylinder 6. The first portion 61 is continuous in the direction in which the linear motion unit 52 moves linearly. This results in the linear motion unit 52 of the linear motion mechanism 5 being able to move linearly as long as the portion having the pressing surface 56 does not protrude beyond the first portion 61. In the present embodiment, the entire cylinder 6 extends in the axis direction DA. The cylinder 6 is arranged coaxially with the axis LA.

[0057] The cylinder 6 receives the fluid L. The fluid L is received in the cylinder 6 in such a way that it lies overlapping the first section 61 of the cylinder 6 and a second section 62 of the cylinder 6, described below.

[0058] The material of the fluid L is not particularly limited as long as a linear motion input from the linear motion mechanism 5 can be transmitted to the output member 7 described below. The fluid L may be a liquid or a gas. In view of the fact that the linear motion input from the linear motion mechanism 5 is efficiently transmitted to the output member 7 and, as described below, the shock transmitted to the linear motion mechanism 5 or the like is dampened by the fluid L, the fluid L is preferably a material with high viscosity. Since oil generally has a higher viscosity than water, for example, oil is more suitable than water for the material of the fluid L. In the case where the fluid L is a gas, for example, a gas compressed at high pressure can be used as the fluid L.

[0059] The output element 7 will be described. The output element 7 is a member to which a straight line input from the linear motion mechanism 5 is transmitted via the fluid L. In the present embodiment, the output element 7 is arranged on the first side SA1 of the axis direction DA of the cylinder 6. In the present embodiment, the output element 7 is a rod-shaped member. The output element 7 extends in the axis direction DA. The output element 7 is arranged coaxially with the axis LA.

[0060] The output element 7 has a surface 71 that is pressed by the fluid L. The surface 71 of the output element 7 that is pressed by the fluid L is also referred to as the pressed surface 71. The pressed surface 71 is a surface that is pressed by the fluid L when a linear movement is transmitted to the output element 7 via the fluid L. In the present embodiment, the surface of the output element 7 located on the second side SA2 of the axial direction DA forms the pressed surface 71.

[0061] Here, the cylinder 6 receives the portion of the output element 7 having the pressed surface 71. In the present embodiment, a part of the output element 7 penetrates into the interior of the cylinder 6 through an opening of the tubular cylinder 6 located on the second side SA2 of the axial direction DA. In this way, the cylinder 6 receives the portion of the output element 7 having the pressed surface 71.

[0062] In the present embodiment, the cylinder 6 includes a portion in which a hollow portion is formed, which has the same shape as the pressed surface 71 in the cross section perpendicular to the direction in which the portion of the output member 7 accommodated in the cylinder 6 extends (the axial direction DA). This portion is referred to as the second portion 62 of the cylinder 6. The second portion 62 is continuous in the direction in which the portion of the output member 7 accommodated in the cylinder 6 extends. This results in the output member 7 being able to move linearly along the direction in which the portion of the output member 7 accommodated in the cylinder 6 extends, as long as the portion of the output member 7 having the pressed surface 71 does not protrude beyond the second portion 62.In the present embodiment, the linear motion unit 52 of the linear motion mechanism 5 and the output member 7 move linearly on the same line. Specifically, the linear motion unit 52 of the linear motion mechanism 5 and the output member 7 move linearly on the LA axis.

[0063] The output member 7 of the present embodiment further includes a mounting portion 72 on which an action portion driven by the linear motion device 1 is mounted. The mounting portion 72 is provided in an end portion of the output member 7 on the side opposite the side on which the pressed surface 71 is arranged (on the first side SA1 of the axis direction DA). The shape of the mounting portion 72 is not particularly limited as long as the action portion driven by the linear motion device 1 can be mounted thereon. In the present embodiment, the mounting portion 72 is a rod end, which may be coupled to another member. In this case, the mounting portion 72, namely the rod end, may have an annular shape.

[0064] In the present embodiment, the cylinder 6 has a tubular shape as described above. The linear motion mechanism 5 has the surface 56 (the pushing surface 56) that pushes the fluid L when linear motion is input to the fluid L. The output member 7 has the surface 71 (the pushed surface 71) that is pushed by the fluid L when linear motion is transmitted via the fluid L. The fluid L is enclosed in a space 65 surrounded by the inner surface of the cylinder 6, the surface 56 that pushes the fluid L of the linear motion mechanism 5, and the surface 71 that is pushed by the fluid L of the output member 7.

[0065] Here, the cylinder 6, which has a tubular shape, can have a cylindrical shape or, alternatively, a square tubular shape. In the case where the cylinder 6 has a square tubular shape, the shape of the hollow portion in the cross section perpendicular to the direction in which the cylinder 6 extends can be a triangle, a quadrilateral, or another polygon. If the cylinder 6 has a square tubular shape at least in the first portion 61, the following effects can be achieved. By making the shape of the pressing surface 56 the same as the shape of the hollow portion of the first portion 61 in the cross section perpendicular to the direction in which the cylinder 6 extends, the linear motion unit 52 having the pressing surface 56 can be prevented from rotating relative to the cylinder 6 in the circumferential direction DB.Furthermore, if the cylinder 6 has a square tubular shape at least in the second portion 62, the following effects can be achieved. By making the shape of the pressed surface 71 the same as the shape of the hollow portion of the second portion 62 in the cross section perpendicular to the direction in which the cylinder 6 extends, the output member 7 having the pressed surface 71 can be prevented from rotating relative to the cylinder 6 in the circumferential direction DB.

[0066] In the present embodiment, the surface area of ​​the pressing surface 56 and the surface area of ​​the pressed surface 71 are different from each other. Specifically, the surface area of ​​the pressing surface 56 is larger than the surface area of ​​the pressed surface 71. Furthermore, in the present embodiment, the cross-sectional area of ​​the hollow portion of the cylinder 6 with respect to the first portion 61 in the cross section perpendicular to the direction in which the linear motion unit 52 linearly moves (the axis direction DA) and the cross-sectional area of ​​the hollow portion of the cylinder 6 with respect to the second portion 62 in the direction in which the output member 7 linearly moves (the axis direction DA) are different from each other. The cross-sectional area of ​​the hollow portion of the cylinder 6 with respect to the first portion 61 is larger than the cross-sectional area of ​​the hollow portion of the cylinder 6 with respect to the second portion 62.

[0067] The linear motion device 1 of the present embodiment further includes a receiving member 81 that receives at least the rotary unit 51 of the linear motion mechanism 5, which rotates by a rotational motion input from the drive unit 2. The linear motion device 1 of the present embodiment further includes a bearing 82 that is in contact with the rotary unit 51 and the receiving member 81 such that the rotary unit 51 can rotate relative to the receiving member 81.

[0068] In the present embodiment, the receiving member 81 receives at least a part of the rotating unit 51. The receiving member 81 covers the rotating unit 51 of the linear motion mechanism 5 from the radial direction DC. In the present embodiment, the third member 48 is fixed to the first member 41 (the housing 41a) of the reducing portion 4. The third member 48 extends toward the first side SA1 of the axial direction DA. The nut 55 constituting the rotating unit 51 of the linear motion mechanism 5 is received in the extending portion of the third member 48. In this case, it can be said that a part of the third member 48 constitutes the receiving member 81.

[0069] It should be noted that the cylinder 6 may extend toward the second side SA2 of the axial direction DA, allowing the cylinder 6 to receive the rotary unit 51. In this case, it can be said that a part of the cylinder 6 forms the receiving element 81. Alternatively, the receiving element 81 may be a member that is different from both the element included in the reduction section 4 and the cylinder 6.

[0070] In the present embodiment, the bearing 82 is in contact with the rotating unit 51 and the portion of the third member 48 forming the receiving member 81 such that the rotating unit 51 can rotate relative to the portion of the third member 48 forming the receiving member 81. The type of the bearing 82 is not particularly limited as long as it can be in contact with the rotating unit 51 and the receiving member 81 such that the rotating unit 51 can rotate relative to the receiving member 81.

[0071] It should be noted that in the case where a part of the cylinder 6 forms the receiving element 81, the bearing 82 is in contact with the rotating unit 51 and the portion of the cylinder 6 forming the receiving element 81 such that the rotating unit 51 can rotate relative to the portion of the cylinder 6 forming the receiving element 81.

[0072] In the present embodiment, the end portion of the cylinder 6 located on the second side SA2 of the axial direction DA and the end portion of the third member 48 of the reduction section 4 located on the first side SA1 of the axial direction DA are connected to each other. Furthermore, the end portion of the first member 41 of the reduction section 4 located on the second side SA2 of the axial direction DA and the end portion of the mounting member 47 of the reduction section 4 located on the first side SA1 of the axial direction DA are connected to each other. Thus, the portion of the output member 7 having the pressed surface 71, the linear motion mechanism 5, and the second member 42 (the carrier 42a), and the reduction mechanism 45 of the reduction section 4 are accommodated in a space defined by the cylinder 6, the first member 41 of the reduction section 4, the mounting member 47, and the third member 48.Thereby, the portion of the output member 7 having the pressed surface 71, the linear movement mechanism 5 and the second member 42 (the carrier 42a) and the reduction mechanism 45 of the reduction portion 4 can be protected from external dust, etc.

[0073] The linear motion device 1 of the present embodiment further includes a first sealing member 85 for sealing between the portion of the output member 7 located further on the mounting portion 72 side than the pressed surface 71 and the cylinder 6. This allows the pressed surface 71 of the output member 7 and the like to be protected more stably. The linear motion device 1 of the present embodiment further includes a second sealing member 86 for sealing between the portion of the linear motion unit 52 located further on the drive unit 2 side than the pressing surface 56 and the cylinder 6. This allows the fluid L to be prevented from mixing with a lubricating oil or the like used for the linear motion mechanism 5, the reduction portion 4, and the like.

[0074] The linear motion device 1 of the present embodiment further includes an accumulator 83. The accumulator 83 has a first chamber 831 opened on the inner surface of the cylinder 6 to communicate with the space 65, and a second chamber 832 whose volume changes depending on the pressure in the first chamber 831 to change the volume of the first chamber 831. In the present embodiment, the accumulator 83 has the shape of a container opened on the inner surface of the cylinder 6 to communicate with the space 65. The first chamber 831 and the second chamber 832 are formed inside the accumulator 83. The first chamber 831 communicates with the space 65 via the opening. Therefore, the fluid L enters the first chamber 831. The second chamber 832 is separated from the first chamber 831 by a separation diaphragm 833.The separation membrane 833 deforms depending on the pressure difference between the first chamber 831 and the second chamber 832. The second chamber 832 is filled with a gas, such as nitrogen, for example.

[0075] When the pressure in the space 65 and the first chamber 831 is higher than the pressure in the second chamber 832, the separation membrane 833 deforms due to the pressure difference between the first chamber 831 and the second chamber 832, thereby reducing the volume of the second chamber 832. When the volume of the second chamber 832 is reduced, the volume of the first chamber 831 is increased. When the pressure in the space 65 and the first chamber 831 is lower than the pressure in the second chamber 832, the separation membrane 833 deforms due to the pressure difference between the first chamber 831 and the second chamber 832, thereby increasing the volume of the second chamber 832. When the volume of the second chamber 832 is increased, the volume of the first chamber 831 is reduced. In this way, the volume of the second chamber 832 changes depending on the pressure in the first chamber 831 to change the volume of the first chamber 831.In the event that, as described above, the pressure in the space 65 is high, the pressure accumulator 83 serves to increase the volume of the first chamber 831 into which the fluid L can enter, and in the event that the pressure in the space 65 is low, the pressure accumulator 83 serves to reduce the volume of the first chamber 831 into which the fluid L can enter.

[0076] The action of the linear motion device 1 of the present embodiment will be described below. First, the action of the linear motion device 1 will be described in the case where the acting section is driven by the linear motion device 1. The acting section is, for example, a construction machine such as an excavator, a railway brake, or the like. When driving the acting section by the linear motion device 1, the acting section is mounted on the mounting section 72 of the output member 7. Rotation is then output from the drive unit 2. In the case where the drive unit 2 includes the electric mechanism 3 and the reduction section 4, the drive unit 2 outputs rotation output from the electric mechanism 3 and decelerated by the reduction section 4. Thereby, rotational motion is input from the drive unit 2 to the linear motion mechanism 5.Subsequently, the linear motion mechanism 5 converts the rotational motion input from the drive unit 2 into linear motion. In the present embodiment, rotational motion is converted into linear motion by driving the linear motion unit 52 by a rotational motion of the rotary unit 51, which rotates by a rotational motion input from the drive unit 2, and moves linearly. As a result, the portion of the linear motion unit 52 having the pressing surface 56 moves linearly inside the cylinder 6, specifically, inside the first portion 61 of the cylinder 6. Therefore, the fluid L accommodated inside the cylinder 6 is pressed by the pressing surface 56. In the present embodiment, the fluid L is pressed by the pressing surface 56 toward the first side SA1 of the axis direction DA.The fluid L pressed by the pressing surface 56 presses the portion of the output member 7 having the pressed surface 71. In the present embodiment, the fluid L presses the portion of the output member 7 having the pressed surface 71 toward the first side SA1 of the axis direction DA. As a result, the output member 7 is pressed by the fluid L, causing the output member 7 to move linearly along the direction in which the portion of the output member 7 accommodated in the cylinder 6 extends. Consequently, the action portion mounted on the mounting portion 72 of the output member 7 can move linearly together with the output member 7.

[0077] The following describes the effect that, when the linear motion device 1 receives an impact from the side that outputs a linear motion, the impact transmitted to the linear motion mechanism 5 is dampened. Specifically, the effect that, when the linear motion device 1 receives an impact from the acting portion mounted on the mounting portion 72 of the output member 7, the impact transmitted to the linear motion mechanism 5 is dampened. When the linear motion device 1 receives an impact from the acting portion mounted on the mounting portion 72 of the output member 7, the output member 7 may be pushed toward the side on which the linear motion mechanism 5 is located (the second side SA2 of the axis direction DA). In this case, it is conceivable that the output member 7 moves toward the second side SA2 of the axis direction DA and pushes the fluid L.

[0078] Here, the linear motion device 1 of the present embodiment includes the linear motion mechanism 5 that converts a rotary motion input from the drive unit 2 into a linear motion, the cylinder 6 that accommodates the fluid L to which the linear motion is input from the linear motion mechanism 5, and the output member 7 to which the linear motion input from the linear motion mechanism 5 is transmitted via the fluid L. Therefore, the fluid L is located between the output member 7 and the linear motion mechanism 5. When the fluid L is located between the output member 7 and the linear motion mechanism 5, the shock transmitted from the output member 7 to the linear motion mechanism 5 can be dampened by the fluid L.In particular, in the case where a temporary strong shock is applied to the action portion mounted on the output member 7, the shock transmitted from the output member 7 to the linear motion mechanism 5 can be dampened by the fluid L. According to the linear motion device 1 of the present embodiment, the shock transmitted to the linear motion mechanism 5 can be dampened in this way.

[0079] In the present embodiment, the drive unit 2 is located on the opposite side of the linear motion mechanism 5 from the side on which the output member 7 and the cylinder 6 are located. Here, according to the linear motion device 1 of the present embodiment, the shock transmitted from the output member 7 to the linear motion mechanism 5 is dampened by the fluid L, whereby a strong shock can be prevented from being transmitted from the output member 7 to the drive unit 2.

[0080] In the present embodiment, the drive unit 2 includes the electric mechanism 3 and the reduction section 4, which decelerates rotation of the electric mechanism 3 and transmits it to the linear motion mechanism 5. By including both the electric mechanism 3 and the reduction section 4 in the drive unit 2, the following effects can be achieved. If the drive unit 2 does not include the reduction section 4, it becomes necessary to increase the size of the electric mechanism 3 in order to output a large torque to the drive unit 2. In contrast, if the drive unit 2 includes the reduction section 4, a large torque can be output to the drive unit 2 while reducing the size of the electric mechanism 3 used.Furthermore, according to the linear motion device 1 of the present embodiment, in the case where the drive unit 2 includes the electric mechanism 3 and the reduction section 4, the shock transmitted from the output member 7 to the linear motion mechanism 5 is dampened by the fluid L, whereby a strong shock can be prevented from being transmitted from the output member 7 to the electric mechanism 3 and the reduction section 4. This can stably protect the reduction section 4 from shock.

[0081] In the present embodiment, as described above, the reduction section 4 includes the first member 41 having the internal teeth 412, the second member 42 relatively rotatable relative to the first member 41, the crankshafts 43 rotatably supported on the second member 42, and the external gears 44 provided with the through holes 44d through which the respective crankshafts 43 pass, and the external teeth 441a and 442a meshing with the internal teeth 412 of the first member 41. According to the linear motion device 1 of the present embodiment, even when the aforementioned reduction section 4 is used as the reduction section 4, the reduction section 4 can be stably protected from impact.

[0082] In the present embodiment, the fluid L is enclosed in the space 65 surrounded by the inner surface of the cylinder 6, the surface 56 that pushes the fluid L of the linear motion mechanism 5, and the surface 71 pressed by the fluid L of the output member 7. Therefore, when driving the action portion by the linear motion device 1, the force with which the pressing surface 56 pushes the fluid L can be efficiently transmitted to the output member 7 via the fluid L.

[0083] In the present embodiment, the surface area of ​​the surface 56 that presses the fluid L of the linear motion mechanism 5 (the pressing surface 56) and the surface area of ​​the surface 71 that is pressed by the fluid L of the output member 7 (the pressed surface 71) are different from each other. Furthermore, in the present embodiment, the cross-sectional area of ​​the hollow portion of the cylinder 6 with respect to the first portion 61 in the cross section perpendicular to the direction in which the linear motion unit 52 linearly moves (the axis direction DA) and the cross-sectional area of ​​the hollow portion of the cylinder 6 with respect to the second portion 62 in the direction in which the output member 7 linearly moves (the axis direction DA) are different from each other. Thus, according to Pascal's law, the ratio of the moving distance of the pressed surface 71 to the moving distance of the pressing surface 56 can be controlled.For example, if the surface area of ​​the pressing surface 56 is larger than the surface area of ​​the pressed surface 71, the ratio of the moving distance of the pressed surface 71 to the moving distance of the pressing surface 56 may be greater than 1. Alternatively, the surface area of ​​the surface 56 that presses the fluid L of the linear motion mechanism 5 (the pressing surface 56) may be smaller than the surface area of ​​the surface 71 that is pressed by the fluid L of the output element 7 (the pressed surface 71). If the surface area of ​​the pressing surface 56 is smaller than the surface area of ​​the pressed surface 71, the ratio of the moving distance of the pressed surface 71 to the moving distance of the pressing surface 56 may be less than 1. Similarly, the ratio of the moving speed of the pressed surface 71 to the moving speed of the pressing surface 56 can be controlled.

[0084] The effect resulting from the fact that the surface area of ​​the pressing surface 56 and the surface area of ​​the pressed surface 71 differ from each other in the present embodiment will be described in detail. For comparison, consider the linear motion device 1 in which the surface area of ​​the pressing surface 56 and the surface area of ​​the pressed surface 71 are the same. In this case, it is necessary to move the linear motion unit 52 at the same speed as the desired linear motion output by the linear motion device 1 over the same movement distance as the desired linear motion output by the linear motion device 1.For example, in the case where the linear motion mechanism 5 includes the ball screw 53, it is necessary to control the pitch of the threads of the external thread 54a of the screw shaft 54 ​​and the internal thread 55a of the nut 55, and the length of the screw shaft 54 ​​in the direction in which the linear motion unit 52 moves linearly, so that the linear motion unit 52 can move at the desired speed over the desired moving distance. On the other hand, according to the linear motion device 1 of the present embodiment, by making the area of ​​the pressing surface 56 and the area of ​​the pressed surface 71 different from each other, a linear motion output from the linear motion mechanism 5 can be transmitted to the output member 7 while converting its speed and moving distance due to the action of the fluid L accommodated in the cylinder 6.This can improve the degree of freedom in selecting the linear motion mechanism 5 used in the linear motion device 1.

[0085] In the present embodiment, the surface area of ​​the surface 56 that presses the fluid L of the linear motion mechanism 5 (the pressing surface 56) is larger than the surface area of ​​the surface 71 that is pressed by the fluid L of the output member 7 (the pressed surface 71). Furthermore, in the present embodiment, the cross-sectional area of ​​the hollow portion of the cylinder 6 with respect to the first portion 61 in the cross section perpendicular to the direction in which the linear motion unit 52 linearly moves (the axis direction DA) is larger than the cross-sectional area of ​​the hollow portion of the cylinder 6 with respect to the second portion 62 in the direction in which the output member 7 linearly moves (the axis direction DA). Thus, according to Pascal's law, the ratio of the moving distance of the pressed surface 71 to the moving distance of the pressing surface 56 can be greater than 1.Therefore, when the linear motion unit 52 of the linear motion mechanism 5 moves linearly at a speed slower than the speed of the linear motion required for the output member 7 over a moving distance shorter than the moving distance of the linear motion required for the output member 7, the desired linear motion of the output member 7 can be achieved. For example, even if the speed and moving distance of the linear motion required for the output member 7 are relatively large, the speed and moving distance of the linear motion required for the linear motion unit 52 can be reduced. Consequently, the size of the linear motion mechanism 5 can be reduced while achieving the desired linear motion of the output member 7.

[0086] In the present embodiment, the drive unit 2 includes the reduction section 4. Further, the area of ​​the pressing surface 56 is larger than the area of ​​the pressed surface 71. Therefore, a rotary motion output from the electric mechanism 3 of the drive unit 2 is first decelerated by the reduction section 4, converted into a linear motion by the linear motion mechanism 5, and then accelerated due to the action of the fluid L accommodated in the cylinder 6 to be transmitted to the output member 7. According to this linear motion device 1, a linear motion, in which movement at a relatively high speed over a long distance is performed, of the output member 7 can be enabled while reducing the size of the electric mechanism 3 and the linear motion mechanism 5 as described above.Furthermore, in the case where the output element 7 is moved linearly at a desired, specific speed over a desired, specific movement distance, the power to be input to the electric mechanism 3 for the linear movement can be kept small.

[0087] The linear motion device 1 of the present embodiment further includes the receiving member 81 that accommodates at least the rotating unit 51 of the linear motion mechanism 5, and the bearing 82 that is in contact with the rotating unit 51 and the receiving member 81 so that the rotating unit 51 can rotate relative to the receiving member 81. As a result, the rotating unit 51 can be held on the receiving member 81 via the bearing 82 while allowing rotation of the rotating unit 51. Furthermore, when a shock is transmitted from the output member 7 to the linear motion mechanism 5, the shock can be dissipated to the receiving member 81 via the bearing 82. This can improve the shock resistance of the linear motion mechanism 5. For example, the elements included in the linear motion mechanism 5, such as the rotating unit 51 and the linear motion unit 52, can be prevented from deforming due to shock.

[0088] The linear motion device 1 of the present embodiment further includes the accumulator 83, which has the first chamber 831, which is opened on the inner surface of the cylinder 6 so as to communicate with the space 65, and the second chamber 832, the volume of which changes depending on the pressure in the first chamber 831 to change the volume of the first chamber 831. When the pressure in the space 65 is high, the accumulator 83 serves to increase the volume of the first chamber 831 into which the fluid L can enter, and when the pressure in the space 65 is low, the accumulator 83 serves to reduce the volume of the first chamber 831 into which the fluid L can enter. Therefore, the accumulator 83 can prevent the pressure in the space 65 from suddenly increasing or decreasing.In particular, in the event that, for example, an impact is exerted on the output element 7 and the output element 7 is pressed into the cylinder 6, the pressure in the space 65 can be prevented from rising suddenly.

[0089] The linear motion device 1 of the present embodiment may further include a force sensor for measuring a force applied to the linear motion unit 52 of the linear motion mechanism 5 and the output member 7, and a position sensor for measuring a displacement of the linear motion unit 52 of the linear motion mechanism 5 and the output member 7. When the linear motion device 1 includes the force sensor or the position sensor, it can be detected that an external impact is applied to the linear motion unit 52 and the output member 7. Therefore, when a rotational motion is output from the drive unit 2 to the linear motion mechanism 5 at the time when an external impact is detected to the linear motion unit 52 and the output member 7, a force is generated to repel the impact, whereby the linear motion mechanism 5 and the drive unit 2 can be protected.

[0090] The unit including the linear motion mechanism 5, the cylinder 6, and the output member 7 of the above-described linear motion device 1 of the present embodiment is also referred to as a conversion mechanism 10. The conversion mechanism 10 is the conversion mechanism 10 that converts rotary motion into linear motion, the linear motion mechanism 5 that converts input rotary motion into linear motion, the cylinder 6 that accommodates the fluid L to which the linear motion is input from the linear motion mechanism 5, and the output member 7 to which the linear motion input from the linear motion mechanism 5 is transmitted via the fluid L. According to the conversion mechanism 10, the shock transmitted from the output member 7 to the linear motion mechanism 5 can be dampened by the fluid L.

[0091] The above-described linear motion device 1 of the present embodiment can be used in a construction machine. In this case, the construction machine can be said to include the linear motion device 1 and the acting portion linearly driven by the linear motion device 1. The acting portion is mounted, for example, on the mounting portion 72 of the output member 7. The construction machine is, for example, an excavator. In the case where the construction machine is an excavator, the acting portion is, for example, a boom, an arm, a bucket, or the like of the excavator.According to the construction machine including the linear motion device 1 of the present embodiment, the shock transmitted from the acting portion to the linear motion mechanism 5 can be damped by the fluid L while the acting portion is linearly driven by the linear motion device 1.

[0092] The above-described linear motion device 1 of the present embodiment can be used in a railway brake. In this case, the railway brake can be said to include the linear motion device 1. According to the railway brake including the linear actuator of the present embodiment, the shock transmitted from the acting portion of the railway brake to the linear motion mechanism 5 can be damped by the fluid L while the acting portion of the railway brake is linearly driven by the linear motion device 1.

[0093] The present embodiment is described using specific examples; however, the specific examples do not limit the present embodiment. The present embodiment described above can be implemented in various other specific examples, and various omissions, substitutions, changes, and additions can be made without departing from the gist of the embodiment.

[0094] Examples of modifications are described below with reference to the drawings. In the following description and the drawings used in the following description, parts that may be structured similarly to those of the specific examples described above are denoted by the same reference numerals used for corresponding parts of the specific examples described above, and a repeated description is omitted. (Variation 1)

[0095] In the above-described embodiment, the case is described where, in the linear motion mechanism 5 including the ball screw 53, the nut 55 constitutes the rotary unit 51, and the screw shaft 54 ​​constitutes the linear motion unit 52. However, the shape of the linear motion mechanism 5 is not limited to this. Fig. 4 shows a cross-sectional view of the linear motion device 1 of the modification 1. Fig. 4 shows in particular a cross-sectional view of the linear motion device 1, cut in a plane passing through the axis of rotation LA of a rotation output by the drive unit 2.

[0096] In Modification 1, the screw shaft 54 ​​of the ball screw 53 constitutes the rotary unit 51, and the nut 55 constitutes the linear motion unit 52. In Modification 1, the screw shaft 54 ​​is fixed to the second member 42 (the support 42a) of the reduction section 4. Thus, the screw shaft 54 ​​constitutes the rotary unit 51, which rotates by rotation input from the second member 42. Furthermore, in Modification 1, the nut 55 is not fixed to the second member 42 (the support 42a). Therefore, the nut 55 constitutes the linear motion unit 52, which is driven by rotational motion of the screw shaft 54 ​​constituting the rotary unit 51 and moves linearly.

[0097] In Modification 1, the surface of the nut 55 located on the first side SA1 of the axis direction DA forms the pressing surface 56 that presses the fluid L accommodated in the cylinder 6. In the linear motion mechanism 5 of Modification 1, by driving the nut 55 by a rotational movement of the screw shaft 54 ​​and moving linearly, the fluid L is pressed by the pressing surface 56 formed on the nut 55.

[0098] Furthermore, in Modification 1, the receiving member 81 receives the screw shaft 54 ​​constituting the rotating unit 51. Furthermore, in Modification 1, the bearing 82 is in contact with the screw shaft 54 ​​and the receiving member 81 such that the screw shaft 54 ​​constituting the rotating unit 51 can rotate relative to the receiving member 81. The bearing 82 is in contact with a portion of the screw shaft 54 ​​where no external thread 54a is formed. It should be noted that in Modification 1, the receiving member 81 is a member different from both the member included in the reducing portion 4 and the cylinder 6. The receiving member 81 is connected to the cylinder 6 on the first side SA1 of the axial direction DA and is connected to the second member 42 (the carrier 42a) on the second side SA2 of the axial direction DA.As a result, the interior of the linear motion device 1 is delimited by the receiving element 81, the cylinder 6 and the second element 42 and the mounting element 47 of the reduction section 4.

[0099] The linear motion device 1 of Modification 1 further includes a rotation-preventing member 84 that prevents rotation of the linear motion unit 52 relative to the cylinder 6. The rotation-preventing member 84 is a rod-shaped member that extends inside the first portion 61 of the cylinder 6 in the direction in which the linear motion unit 52 moves linearly. The linear motion device 1 of Modification 1 includes the two rotation-preventing members 84. In Modification 1, the linear motion unit 52 is provided with a through-hole 52a that extends in the direction in which the linear motion unit 52 moves linearly. The rotation-preventing member 84 is passed through the through-hole 52a. The rotation-preventing member 84 is further attached to the receiving member 81. According to this rotation inhibiting element 84, a movement other than a linear movement of the linear motion unit 52 can be inhibited.

[0100] Although not shown, the linear motion mechanism 5 may include a seal portion that prevents the fluid L from entering the through-hole 55b of the nut 55. For example, the seal portion prevents the fluid L from entering between the nut 55 and the screw shaft 54. The seal portion is mounted on the nut 55 constituting the linear motion unit 52 and moves linearly together with the nut 55. (Variation 2)

[0101] In the above-described embodiment and modification, the case where the linear motion unit 52 of the linear motion mechanism 5 and the output member 7 linearly move on the same line is described. However, the shape of the linear motion device 1 is not limited to this. Fig. 5 shows a cross-sectional view of the linear motion device 1 of the modification 1. Fig. 5 shows in particular a cross-sectional view of the linear motion device 1, cut in a plane passing through the rotation axis LA of a rotation output by the drive unit 2 and an axis LB of the output element 7.

[0102] In variation 2, the first section 61 of the cylinder 6 is arranged coaxially with the LA axis. Therefore, the linear motion unit 52 moves linearly along the LA axis. In contrast, the second section 62 of the cylinder 6 is not arranged coaxially with the LA axis. Therefore, the LB axis of the output element 7 does not coincide with the LA axis of rotation of a rotation output by the drive unit 2 and the axis of the linear motion unit 52.

[0103] In Modification 2, the linear motion unit 52 moves linearly along the LA axis. Furthermore, the output element 7 moves linearly along the LB axis, which is not aligned with the LA axis. Therefore, in Modification 2, the linear motion unit 52 and the output element 7 move linearly along different lines.

[0104] In Variation 2, the first portion 61 and the second portion 62 may extend in mutually parallel directions or in mutually non-parallel directions. Furthermore, the linear motion unit 52 and the output element 7 may move linearly along mutually parallel lines or linearly along mutually non-parallel lines.

[0105] In Modification 2, in addition to the first portion 61 in which the portion of the linear motion unit 52 having the pressing surface 56 can move, and the second portion 62 in which the portion of the output element 7 having the pressed surface 71 can move, the cylinder 6 includes a third portion 63 that extends non-parallel to the direction in which the first portion 61 and the second portion 62 extend, and connects the first portion 61 to the second portion 62. The fluid L is accommodated in the cylinder 6 such that it fills the third portion 63 and straddles the first portion 61 and the second portion 62.Therefore, in Modification 2, as in the above-described embodiment and modification, the pressing surface 56 of the linear motion unit 52 presses the fluid L, and thereby the pressed surface 71 of the output member 7 is pressed by the fluid L, whereby the output member 7 moves linearly. (Variation 3)

[0106] The third section 63, which connects the first section 61 to the second section 62, of the cylinder 6 may comprise a section made of a flexible material. Fig. 6 shows a cross-sectional view of the linear motion device 1 of the modification 3. Fig. 6 shows in particular a cross-sectional view of the linear motion device 1, cut in a plane passing through the axis of rotation LA of a rotation output by the drive unit 2 and the axis LB of the output element 7.

[0107] In Modification 3, the third portion 63 of the cylinder 6 includes a deformation portion 64 made of a flexible material. The material of the deformation portion 64 is not particularly limited as long as it has flexibility and can transmit a linear motion input from the linear motion mechanism 5 to the output member 7. The deformation portion 64 is, for example, a rubber tube. Also in Modification 3, the fluid L is accommodated in the cylinder 6 so as to fill the third portion 63 and straddle the first portion 61 and the second portion 62. Therefore, in Modification 3, as in the embodiment and the modifications described above, the pressing surface 56 of the linear motion unit 52 presses the fluid L, and thereby the pressed surface 71 of the output member 7 is pressed by the fluid L, causing the output member 7 to move linearly.

[0108] According to the linear motion device 1 of the modification 3, the positional relationship between the output member 7, the linear motion mechanism 5 and the drive unit 2 can be freely changed by deforming the deformation portion 64. (Variation 4)

[0109] In the embodiment and modifications described above, the case where the linear motion mechanism 5 includes the ball screw 53 is described. However, the shape of the linear motion mechanism 5 is not limited thereto. Fig. 7 and Fig. 8 each show a cross-sectional view of the linear motion device 1 of the modification 4. Fig. In particular, Figure 7 shows a cross-sectional view of the linear motion device 1, cut in a plane passing through the axis LB of the output element 7 and perpendicular to the axis LA. In Fig. 8 is a cross section along the line VIIIa-VIIIa in Fig. 7 is shown a cross-sectional view of the linear motion device 1 on the side of the output element 7 relative to the dashed line marked with a symbol L1. A cross-section of the device taken along the line VIIIb-VIIIb in Fig. 7 sectioned linear motion device 1 is shown on the side of the drive unit 2 relative to the dashed line marked with the character L1.

[0110] In Modification 4, the linear motion mechanism 5 includes a rack 58 and a pinion 59. The rack 58 is a rod-shaped member having teeth 58a. The teeth 58a are located on the side surface of the rack 58 and are juxtaposed along the direction in which the rack extends. In Modification 4, the rack 58 extends in the direction in which the axis LB of the output member 7 extends. The pinion 59 has a generally circular gear shape. The teeth 58a of the rack 58 mesh with teeth 59a of the pinion 59. Therefore, when the pinion 59 rotates, the rack 58 is driven by the pinion 59, thereby changing the positional relationship between the rack 58 and the pinion 59. In other words, the linear motion mechanism 5 comprises a so-called rack and pinion.

[0111] In Modification 4, the pinion 59 constitutes the rotary unit 51, which rotates by a rotary motion input from the drive unit 2. The pinion 59 is fixed to the end portion of the second member 42 located on the first side SA1 of the axial direction DA. In Modification 4, further, the rack 58 constitutes the linear motion unit 52, which is driven by a rotary motion of the rotary unit 51 and moves linearly. In Modification 4, when a rotary motion is output from the drive unit 2, the rotary motion is input to the pinion 59, causing the pinion 59 to rotate in the circumferential direction DB. When the pinion 59 rotates, the rack 58 is driven by the rotary motion of the pinion 59. At this time, the rack 58 moves linearly in the direction in which the rack 58 extends.Consequently, the linear motion mechanism 5 of the modification 4 can also convert a rotary motion input from the drive unit 2 into a linear motion.

[0112] In Modification 4, the rack 58 constituting the linear motion unit 52 moves linearly on the line that does not coincide with the rotation axis LA of a rotation output from the drive unit 2. In Modification 4, the rack 58 moves linearly in the direction orthogonal to the axis direction DA in which the axis LA extends. Note that in Modification 4, the rack 58 is arranged coaxially with the axis LB of the output element 7 and moves linearly on the axis LB.

[0113] Among the embodiments disclosed in this specification, with respect to a component consisting of multiple objects, the multiple objects may be integrated, and conversely, a component consisting of one object may be divided into multiple objects. Regardless of whether integration occurs, it is sufficient if the design is such that the purpose of the invention is achieved.

[0114] The aspects of the present invention are not limited to the individual embodiments described above, but include various modifications conceivable by those skilled in the art, and the effects of the present invention are also not limited to the above-described content. That is, various additions, changes, and partial deletions can be made without departing from the conceptual spirit and gist of the present invention, which are derived from the content defined in the claims and their equivalents. List of reference symbols 1 linear motion device 2 drive unit 3 electric mechanism 31 Rotating shaft 4 Reduction section 41 first element 42 second element 43 Crankshaft 44 External gear 5 Linear motion mechanism 53 Ball screw 54 screw shaft 55 mother 56 pressing surface 6 cylinders 65 Room 7 Output element 81 receiving element 82 warehouses 83 pressure accumulators 10 Conversion mechanism QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2013 / 114451

[0004]

Claims

[1] Linear motion device 1, comprising: a drive unit 2 that outputs rotation; a linear motion mechanism 5 that converts a rotary motion input from the drive unit 2 into a linear motion; a cylinder 6 which accommodates a fluid L into which the linear motion is input from the linear motion mechanism 5; and an output element 7 to which the linear movement input from the linear movement mechanism 5 is transmitted via the fluid L. [2] The linear motion device 1 according to claim 1, wherein the drive unit 2 includes an electric mechanism 3 and a reduction section 4 that slows down a rotation of the electric mechanism 3 and transmits it to the linear motion mechanism 5. [3] The linear motion device 1 according to claim 1, wherein an area of ​​a surface 56 that presses the fluid L of the linear motion mechanism 5 and an area of ​​a surface 71 that is pressed by the fluid L of the output member 7 are different from each other. [4] The linear motion device 1 according to claim 3, wherein the area of ​​the surface 56 that presses the fluid L of the linear motion mechanism 5 is larger than the area of ​​the surface 71 that is pressed by the fluid L of the output member 7. [5] Linear motion device 1 according to claim 1, wherein the cylinder 6 has a tubular shape, wherein the linear motion mechanism 5 has a surface 56 which presses the fluid L, wherein the output element 7 has a surface 71 which is pressed by the fluid L, and wherein the fluid L is enclosed in a space 65 surrounded by an inner surface of the cylinder 6, the surface 56 that pushes the fluid L of the linear motion mechanism 5 and the surface 71 that is pushed by the fluid L of the output element 7. [6] The linear motion device 1 according to claim 5, further comprising an accumulator 83 having a first chamber 831 opened on the inner surface of the cylinder 6 so as to communicate with the space 65, and a second chamber 832 whose volume changes depending on a pressure in the first chamber 831 to change a volume of the first chamber 831. [7] Linear motion device 1 according to claim 1, further comprising: a receiving member 81 that receives at least one rotary unit 51, which rotates by a rotary motion input from the drive unit 2, of the linear motion mechanism 5; and a bearing 82 which is in contact with the rotating unit 51 and the receiving element 81 such that the rotating unit 51 can rotate relative to the receiving element 81. [8] Linear motion device 1 according to claim 2, wherein the reduction section 4 comprises: a first element 41 having internal teeth 412; a second member 42 relatively rotatable relative to the first member 41; a crankshaft 43 rotatably supported on the second member 42; and an external gear 44 provided with a through-hole 44d through which the crankshaft 43 passes, and having external teeth 441a and 442a which mesh with the internal teeth 412 of the first element 41, wherein rotation of the second member 42 is input to the linear motion mechanism 5. [9] Linear motion device 1 according to claim 1, wherein the linear motion mechanism 5 comprises a ball screw 53 comprising a screw shaft 54 ​​and a nut 55. [10] Conversion mechanism 10 which converts a rotary motion into a linear motion, comprising: a linear motion mechanism 5 that converts an input rotary motion into a linear motion; a cylinder 6 which accommodates a fluid L into which the linear motion is input from the linear motion mechanism 5; and an output element 7 to which the linear movement input from the linear movement mechanism 5 is transmitted via the fluid L. [11] Construction machine, comprising: the linear motion device 1 according to one of claims 1 to 9; and an action section which is linearly driven by the linear motion device 1. [12] Railway brake comprising the linear motion device 1 according to any one of claims 1 to 9.

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