Reduction gearbox

Abstract

The reduction gear comprises a reduction mechanism and a transmission gear 40. The transmission gear 40, in its engaged state, is connected to the input shaft via splines at one end and is secured axially by a stop element. The transmission gear 40 meshes with an input gear 30, driven by a power source, to transmit the drive force from the input gear 30 to the input shaft. A recess 45 is provided on the outer face of the transmission gear 40, which receives the end of the input shaft and the engagement section of the stop element.The recess 45 is designed to satisfy two conditions, namely a condition in which the tooth width w2 of the splines of the input shaft and the transmission gear 40 is 60% or more of the tooth width w1 of the transmission gear 40, and the other condition in which the axially orthogonal plane S1, which passes through the axial center ac of the tooth width w1 of the transmission gear 40, lies within the area of ​​the tooth width w2 of the splines of the input shaft and the transmission gear 40.

Description

Technical field

[0001] The present invention relates to a reduction gear. State of the art

[0002] In industrial robots, machine tools and similar applications, reduction gears are used to reduce the speed of a drive source such as a motor (see, for example, patent document 1).

[0003] The reduction gear described in patent document 1 has internal teeth on the inner circumference of a cylindrical housing. Inside the housing is a reduction mechanism that meshes with the internal teeth to reduce the input rotation. The reduction mechanism comprises a carrier rotatably mounted in the housing, a crankshaft (input shaft) rotatably mounted on the carrier, and a rocker gear that oscillates under the influence of the pivoting force from the eccentric section of the crankshaft.

[0004] The oscillating gear has external teeth that mesh with the internal teeth of the housing, the external teeth having fewer teeth than the internal teeth of the housing. A transmission gear (spur gear) is fixed to the crankshaft of the reduction mechanism. The transmission gear meshes with an input gear on the drive source side.

[0005] In this reduction gearbox, the reduction mechanism is activated by transferring the torque via the input gear and the transmission gear to the crankshaft, causing the eccentric section of the crankshaft to rotate eccentrically. This reduces the power on the drive side of the reduction mechanism to a predetermined reduction ratio and delivers it to the carrier or housing.

[0006] In the reduction gear described in patent document 1, a male splined shaft is also formed at the end of the crankshaft and a female splined shaft is formed on the transmission gear mounted on the crankshaft.

[0007] The male splined shaft of the crankshaft has multiple splines spaced circumferentially. These splines extend from the end of the crankshaft along its axial direction towards the side of the reduction mechanism. Furthermore, the male splines feature grooves located between adjacent splines circumferentially. At the end of the groove on the reduction mechanism side, an inclined section is provided. This inclined section is angled within the groove so that it extends radially outwards from the crankshaft as it approaches the reduction mechanism side.

[0008] Therefore, when the female splines of the transmission gear are engaged with the male splines of the crankshaft, the teeth of the female splines press into the inclined sections of the male splines. This reduces rattling in the transmission gear. State-of-the-art documents, patent documents

[0009] [Patent Document 1] Japanese published patent application no. 2014-92249 Disclosure of the invention. Problem of the invention.

[0010] In the reduction gear described in patent document 1, the end of the crankshaft projects axially outwards beyond the end face of the support. A transmission gear is also mounted at the end of the projecting crankshaft. The transmission gear engages with one end of the crankshaft via splined teeth and is axially secured to the crankshaft by a stop element, for example, a retaining ring, to maintain the engagement.

[0011] The axial end of the crankshaft must project a certain length or more beyond the face of the transmission gear so that the stop element can engage with the outer circumference of the crankshaft. This increases the axial length of the crankshaft by the amount by which it projects beyond the face of the transmission gear. Therefore, the increased crankshaft length hinders the miniaturization of the entire reduction gear.

[0012] To solve these problems, it is conceivable to provide a recess in the end face of the transmission gear (in the end face that points outwards in the axial direction) and to arrange the end of the crankshaft and the engagement section of the stop element within this recess.

[0013] Since the stop element is located in the recess of the transmission gear in this case, the axial length of the crankshaft can be shortened. However, the meshing section of the transmission gear is offset axially inwards in the crankshaft by the amount of the recess via the splined connection.

[0014] This results in the axial offset of the tooth width of the transmission gear and the axial center of the meshing section (mesh section above the splined connection) between the transmission gear and the crankshaft. This phenomenon leads to a wobble in the transmission gear during power transmission. This wobble can easily cause vibration noise during operation of the reduction gear.

[0015] One object of the present invention is to propose a reduction gear in which the axial length of the input shaft of the reduction mechanism can be shortened and at the same time the generation of vibration noise during operation can be minimized. Solution of the invention

[0016] A reduction gear according to one aspect of the present invention comprises a reduction mechanism with an input shaft that reduces and outputs the rotation introduced into the input shaft; and a transmission gear which, in the engaged state, engages one end of the input shaft via splined teeth and is secured axially by a stop element, wherein the transmission gear meshes with an input gear driven by a drive source to transmit the driving force from the input gear to the input shaft. A recess is provided on the axially outwardly facing outer face of the transmission gear, which receives the end of the input shaft and the engagement portion of the stop element.The recess is designed to satisfy two conditions: one condition where the comb width of the splines of the input shaft and the transmission gear is 60% or more of the tooth width of the transmission gear, and the other condition where the axially orthogonal plane passing through the axial center of the tooth width of the transmission gear lies within the area of ​​the comb width of the splines of the input shaft and the transmission gear.

[0017] In this design, a recess is provided on the outer face of the transmission gear, in which the end of the input shaft and the engagement section of the stop element are received. Therefore, the axially outer end of the input shaft does not protrude further outwards beyond the transmission gear. Consequently, the axial length of the input shaft can be shortened.

[0018] In this version, a recess is also formed on the outer end surface of the transmission gear such that it fulfills the following two conditions (condition 1) and (condition 2). (Condition 1) The thickness of the splines of the input shaft and the transmission gear is 60% or more of the tooth width of the transmission gear. (Condition 2) An axisorthogonal plane passing through the axial center of the tooth width of the transmission gear lies within the area of ​​the thimble width of the splines of the input shaft and the transmission gear.

[0019] When the input gear and the transmission gear mesh to transmit power, the wobble of the transmission gear is suppressed. Therefore, in this design of the reduction gear, the generation of vibration noise caused by the wobble of the transmission gear is suppressed.

[0020] A reduction gear according to a further aspect of the present invention comprises a housing with internal teeth on its inner circumference; a support rotatably held in the housing; a crankshaft rotatably mounted by the support, wherein an eccentric section of the crankshaft pivots under the influence of an externally acting rotational force; a rocker gear with external teeth meshing with internal teeth, the external teeth having fewer teeth than the internal teeth, and wherein the rocker gear rotates oscillatingly under the influence of the pivoting force from the eccentric section of the crankshaft and transmits the output rotation to the support; and a transmission gear which, in the engaged state, engages with one end of the crankshaft via splined teeth and is secured axially by a stop element, wherein the transmission gear meshes with an input gear driven by a drive source.to transmit the driving force from the input gear to the crankshaft. A recess is provided on the axially outwardly facing outer face of the transmission gear, which accommodates the end of the crankshaft and the engagement section of the stop element. The recess is designed to satisfy two conditions: firstly, that the mesh width of the splines of the crankshaft and transmission gear is 60% or more of the tooth width of the transmission gear; and secondly, that the axially orthogonal plane passing through the axial center of the tooth width of the transmission gear lies within the area of ​​the mesh width of the splines of the crankshaft and transmission gear.

[0021] In this design, a recess is provided on the outer face of the transmission gear, in which the end of the crankshaft and the engagement section of the stop element are received. Therefore, the axially outer end of the crankshaft does not protrude further outwards beyond the transmission gear. This allows the axial length of the crankshaft to be reduced.

[0022] In this version, a recess is also formed on the outer end surface of the transmission gear such that it fulfills the following two conditions (condition 1A) and (condition 2A). (Condition 1A) The thickness of the splines of the crankshaft and the transmission gear is 60% or more of the tooth width of the transmission gear. (Condition 2A) An axisorthogonal plane passing through the axial center of the tooth width of the transmission gear lies within the range of the thimble width of the splines of the crankshaft and the transmission gear.

[0023] When the input gear and the transmission gear mesh to transmit power, the wobble of the transmission gear is suppressed. Therefore, in this design of the reduction gear, the generation of vibration noise caused by the wobble of the transmission gear is suppressed.

[0024] Furthermore, particularly in the case of the reduction gear, the carrier rotates as the output rotating body when the reduction gear is in operation. In a structure where the crankshaft is mounted at a position offset from the carrier's center of rotation, the transmission gear therefore rotates in mesh with the input gear while pivoting around the carrier's center of rotation. In this case, a force can often act on the transmission gear due to a change in the output of the drive source, etc., causing wobbling behavior. However, in this design, a recess is formed on the outer end face of the transmission gear to satisfy the following two conditions (Condition 1A) and (Condition 2A). This effectively suppresses the vibration noise caused by the wobbling behavior of the transmission gear. Effects of the invention

[0025] According to the reduction gear of the present invention, it is possible to shorten the axial length of the input shaft of the reduction mechanism and at the same time minimize the generation of vibration noise during operation. Brief description of the characters Fig. Figure 1 is a side view of an industrial robot equipped with a reduction gear according to one embodiment. Fig. Figure 2 is a schematic front view of the reduction gear according to the embodiment. Fig. Figure 3 is a cross-sectional view of the reduction gear according to the embodiment along line III-III in Fig. 2. Fig. Figure 4 is an enlarged view of Section IV in Fig. 3 of the reduction gear according to the embodiment. Fig. Figure 5 shows cross-sectional views of a transmission gear according to one embodiment and of a transmission gear according to a comparative example. Examples of implementation

[0026] In the following, an embodiment of the present invention is described with reference to the drawings.

[0027] Fig. Figure 1 is a side view of an industrial robot 100, which is equipped with a reduction gear 10 according to an embodiment.

[0028] As in Fig. As shown in Figure 1, the industrial robot 100 is used, for example, in the manufacture of precision instruments for tasks such as parts feeding and assembly. According to this embodiment, the industrial robot 100 comprises a base 110, a first arm 120, a second arm 130, a working head 140, and an end effector 150.

[0029] The base 110 includes a motor 160 as a drive source, for example a servo motor, as well as a reduction gear 10. The first arm 120 is connected to the output section of the reduction gear 10.

[0030] The first arm 120 rotates around the axis O1. The power of the motor 160 is reduced to a predetermined reduction ratio by the reduction gear 10 and transmitted to the first arm 120. The second arm 130 is rotatably coupled to the distal end of the first arm 120.

[0031] The second arm 130 rotates about an axis parallel to axis O1. The second arm 130 is rotated by the power of a motor (not shown). A working head 140 is held at the distal end of the second arm 130.

[0032] The end effector 150, for example a robot hand, is attached to the working head 140. The end effector 150 is actuated by the power of a motor (not shown).

[0033] Fig. Figure 2 is a front view of the reduction gearbox 10 as seen from the input side (the side to which the motor 160 is connected).

[0034] As in Fig. As shown in Figure 2, the reduction gear 10 comprises three transmission gears 40 (40A, 40B, 40C), each consisting of a spur gear, and an input gear 30, which also consists of a spur gear. The input gear 30 is connected to the output shaft of the motor 160 (see Figure 2). Fig. 1) coupled. The transmission gears 40 and the input gear 30 are each designed as involute gears.

[0035] In Fig. Figure 2 shows the central axis O1 of the input gear 30 and the central axes C1, C2, C3 of the three transmission gears 40A, 40B, 40C. The central axis O1 of the input gear 30 coincides with the central axis O1 of the support described below (first support block 13A and second support block 13B). Furthermore, the central axis O1 of the input gear 30 coincides with the axis O1 that forms the center of rotation of the first arm 120 (see Figure 2). Fig. 1).

[0036] The three transmission gears 40A, 40B, 40C are arranged at substantially equal intervals on an imaginary circle whose center lies on the central axis O1 of the input gear 30. The central axes C1, C2, C3 of the transmission gears 40A, 40B, 40C coincide with the central axes C1, C2, C3 of the three crankshafts 14 described below. The teeth 40a (external teeth) of the three transmission gears 40A, 40B, 40C mesh with the teeth 30a (external teeth) of the input gear 30.

[0037] The rotation introduced by the motor 160 onto the input gear 30 is transferred evenly to the three transmission gears 40A, 40B, 40C, each in the opposite direction of rotation to the rotation of the input gear 30.

[0038] Fig. Figure 3 is a cross-sectional view along line III-III in Fig. 2.

[0039] As in Fig. As shown in Figure 3, the reduction gear 10 comprises a cylindrical housing 11, a first support block 13A, a second support block 13B, three crankshafts 14, a first rocker gear 15A, and a second rocker gear 15B.

[0040] The first support block 13A and the second support block 13B are rotatably mounted on the inner circumferential side of the housing 11. The three crankshafts 14 are rotatably mounted in the first support block 13A and the second support block 13B. The first rocker gear 15A and the second rocker gear 15B rotate pivotally together with the two eccentric sections 14b that each crankshaft 14 has.

[0041] In this embodiment, the housing 11 is attached to the base 110 of the industrial robot 100. The first support block 13A and the second support block 13B form a carrier that serves as the output rotating body. The first oscillating gear 15A and the second oscillating gear 15B each form an oscillating gear that is rotated by the pivoting force of the eccentric section 14b of the crankshaft 14.

[0042] The first support block 13A comprises a perforated, disc-shaped substrate section 13Aa and several support sections 13Ab extending from an end face of the substrate section 13Aa towards the second support block 13B.

[0043] The second support block 13B is designed as a perforated, disc-shaped support block. The first support block 13A is joined to the second support block 13B such that the end faces of the support sections 13Ab rest on an end face of the second support block 13B. Each support section 13Ab is fixed to the second support block 13B by a bolt 16.

[0044] Furthermore, the second support block 13B is provided with positioning pins 17, which serve to align the second support block 13B onto the support sections 13Ab before it is fixed by the bolt 16.

[0045] An axial gap (intermediate space) is provided between the substrate section 13Aa of the first support block 13A and the second support block 13B. The first oscillating gear 15A and the second oscillating gear 15B are arranged in this gap (intermediate space).

[0046] Furthermore, relief bores 19 are formed in both the first oscillating gear 15A and the second oscillating gear 15B, through which the support sections 13Ab of the first support block 13A pass. The relief bores 19 are designed to be larger than the outer contour of the support sections 13Ab, so that the support sections 13Ab do not impede the pivoting movement of the first oscillating gear 15A and the second oscillating gear 15B.

[0047] The housing 11 comprises a cylindrical housing body 11a and a flange 11b, which projects radially outwards from the outer circumferential surface of the housing body 11a. The housing body 11a and the flange 11b are formed, for example, by casting as a single piece.

[0048] The housing body 11a is arranged such that it spans the outer circumferential surface of the substrate section 13Aa of the first support block 13A and the outer circumferential surface of the second support block 13B. On both axial sides of the housing body 11a, the substrate section 13Aa of the first support block 13A and the second support block 13B are rotatably mounted via a bearing 12.

[0049] On the inner circumferential surface of the central region (the region facing the outer circumferential surfaces of the first oscillating gear 15A and the second oscillating gear 15B) in the axial center of the housing body 11a, several pin slots 18 are formed, running parallel to the center of rotation (central axis O1) of the first and second support blocks 13A, 13B. A cylindrical, internally toothed pin 20 is rotatably mounted in each pin slot 18. The multiple internally toothed pins 20, which are located on the inner circumferential surface (pin slots 18) of the housing body 11a, face the outer circumferential surfaces of the first oscillating gear 15A and the second oscillating gear 15B.

[0050] In this embodiment, the internally toothed pins 20, which are housed in the pin grooves 18, form the internal toothing of the housing 11.

[0051] The first oscillating gear 15A and the second oscillating gear 15B are designed such that their outer diameter is slightly smaller than the inner diameter of the housing body 11a. External teeth 15Aa and 15Ba are formed on the outer circumferential surfaces of the first oscillating gear 15A and the second oscillating gear 15B, respectively. These teeth mesh with and are in contact with several internally toothed pins 20, which are arranged on the inner circumferential surface of the housing body 11a. The number of teeth of the external teeth 15Aa and 15Ba of the first oscillating gear 15A and the second oscillating gear 15B is slightly less (e.g., by one) than the number of internally toothed pins 20 (pin slots 18).

[0052] The three crankshafts 14 are arranged on the same circle, the center of which coincides with the center of rotation (central axis O1) of the first support block 13A and the second support block 13B. Each crankshaft 14 is rotatably mounted via a bearing 21 in the first support block 13A and in the second support block 13B.

[0053] Each crankshaft 14 comprises a pair of shaft support sections 14a, which are axially spaced apart, and two eccentric sections 14b, which are arranged between the two shaft support sections 14a of this pair. Gear mounting sections 14c are formed at one axial end of the crankshaft 14, so that they adjoin the shaft support sections 14a. Each shaft support section 14a is guided by a shaft support bore 13Aa-1 formed in the first support block 13A (substrate section 13Aa), as well as by a shaft support bore 13Ba-1 formed in the second support block 13B. Each shaft support section 14a is rotatably mounted in the shaft support bores 13Aa-1 and 13Ba-1 via a bearing 21.

[0054] The gear mounting section 14c of each crankshaft 14 extends through the shaft support bore 13Ba-1 of the second support block 13B and projects axially outwards beyond the second support block 13B. A transmission gear 40 (40A, 40B, 40C) is attached to the gear mounting section 14c. The transmission gear 40 (40A, 40B, 40C) is rotationally fixed to the gear mounting section 14c of the crankshaft 14.

[0055] The two eccentric sections 14b of the crankshaft 14 each have a central axis that is eccentric to the central axis of the shaft support section 14a. Furthermore, the two eccentric sections 14b are arranged eccentrically around the central axis of the shaft support section 14a such that they are phase-shifted by 180° relative to each other.

[0056] Each eccentric section 14b of the crankshaft 14 passes through the respective first rocker gear 15A or second rocker gear 15B. Each eccentric section 14b is rotatably engaged in a support bore 22 via an eccentric bearing 23 (cylindrical roller bearing), which is formed in the first rocker gear 15A or in the second rocker gear 15B.

[0057] When the multiple crankshafts 14 in the reduction gear 10 of this embodiment are rotated in one direction by an external force, the eccentric sections 14b of the crankshafts 14 pivot with a predetermined radius and in the same direction. As a result, the first oscillating gear 15A and the second oscillating gear 15B pivot (oscillate) in the same direction and with the same radius as the pivoting of the eccentric sections 14b. During this process, the external teeth 15Aa, 15Ba of the first oscillating gear 15A and the second oscillating gear 15B mesh and contact the multiple internally toothed pins 20, which are held on the inner circumference of the housing body 11a.

[0058] In the reduction gear 10 of this embodiment, the number of teeth of the external gears 15Aa, 15Ba of the first rocker gear 15A and the second rocker gear 15B is slightly less (for example, by one) than the number of internally toothed pins 20 on the side of the housing body 11a. This causes the first and second rocker gears 15A, 15B, during their complete pivoting motion, which is caused by the rotation of the crankshaft 14, to rotate about their own axis under the influence of a reaction force in the direction of rotation from the internally toothed pins 20 on the side of the housing body 11a, and simultaneously to rotate about a predetermined pitch in the direction opposite to the pivoting direction. As a result, the first and second support blocks 13A, 13B, which are connected to the first and second rocker gears via the crankshaft 14, respectively, rotate.second oscillating gear 15A, 15B are engaged, together with the first and second oscillating gears 15A, 15B in the same direction and with the same pitch.

[0059] As a result, the rotation of the crankshaft 14 is reduced to a predetermined reduction ratio and output as the rotation of the first and second support blocks 13A, 13B. In this embodiment, the first support block 13A is coupled to the first arm 120, which is in Fig. Figure 1 is shown. Therefore, the rotation reduced by the reduction gear 10 is output as the rotation of the first arm 120.

[0060] In this embodiment, the two eccentric sections 14b of the crankshaft 14 are arranged eccentrically such that they are offset by 180° about the central axes C1, C2, C3, whereby the pivoting phases of the first oscillating gear 15A and the second oscillating gear 15B are offset by 180°.

[0061] In this embodiment, the housing 11, the first and second support blocks 13A, 13B, the first and second oscillating gears 15A, 15B, the crankshaft 14, etc., described above, form a reduction mechanism 35 of the reduction gearbox 10. The crankshaft 14 also forms an input shaft of the reduction mechanism 35.

[0062] Fig. 4 is an enlarged view of Section IV of the in Fig. 3 reduction gears shown 10.

[0063] As in Fig. As shown in Figure 4, a male spline 52 is formed on the outer circumferential surface of the gear mounting section 14c of the crankshaft 14, which is formed at the axial end and projects outwards beyond the second support block 13B. A meshing bore 51 is formed in the rotational axis region of the transmission gear 40, which penetrates the transmission gear 40 in the axial direction. A female spline 53 is formed on the inner circumferential surface of the meshing bore 51.

[0064] The female spline 53 of the transmission gear 40 engages with the male spline 52 of the crankshaft 14. The transmission gear 40 is axially secured to the crankshaft 14 by a pair of retaining rings 48, which serve as stop elements, with the female spline 53 engaging with the male spline 52 on the side of the crankshaft 14 (positively coupled). The pair of retaining rings 48 is arranged such that one ring lies axially inside the transmission gear 40 (the side facing the second support block 13B) and the other ring lies axially outside the transmission gear 40 (the side facing away from the second support block 13B). The pair of retaining rings 48 is mounted at the respective positions on the outer circumferential surface of the crankshaft 14.

[0065] Furthermore, an annular engagement groove 54 is formed on the outer circumferential surface of the crankshaft 14. Each retaining ring 48 engages in its respective corresponding engagement groove 54.

[0066] Furthermore, a recess 45 is formed on the axially outwardly directed outer end face of the transmission gear 40, which receives the end of the crankshaft 14 (the section protruding from the engagement bore 51) as well as the engagement section of the retaining ring 48. In this embodiment, the recess 45 is circular in front view. The recess 45 is designed such that its inner diameter on the inner circumferential side of the recess 45 allows the retaining ring 48 to be installed and removed from the end of the crankshaft 14.

[0067] The recess 45 of the transmission gear 40 is designed to meet the following two conditions: (Condition 1A) and (Condition 2A). - (Condition 1A) The tooth width w2 of the splines of the crankshaft 14 and the transmission gear 40 is 60% or more of the tooth width w1 of the transmission gear 40. - (Condition 2A) An axis orthogonal plane S1 passing through the axial center ac of the tooth width w1 of the transmission gear 40 lies within the area of ​​the comb width w2 of the splines of the crankshaft 14 and the transmission gear 40.

[0068] The “axis orthogonal plane S1” is a plane that passes through the axial center ac of the comb section and is orthogonal to the central axis C1 (C2, C3) of the transmission gear 40.

[0069] Furthermore, the reduction gear 10 of this embodiment uses an eccentrically oscillating reduction mechanism as the reduction mechanism 35; however, the structure of the rotary input section described above can also be applied to reduction gears that employ a reduction mechanism other than the eccentrically oscillating type. In this case, the transmission gear 40 can be mounted on the input shaft of the reduction mechanism as described above.

[0070] The recess 45 of the transmission gear is designed such that it fulfills the following two conditions (condition 1) and (condition 2). - (Condition 1) The tooth width w2 of the splined connections of the input shaft and the transmission gear 40 is 60% or more of the tooth width w1 of the transmission gear 40. - (Condition 2) An axis orthogonal plane S1 passing through the axial center ac of the tooth width w1 of the transmission gear 40 lies within the area of ​​the comb width w2 of the splined connections of the input shaft and the transmission gear 40. <Wirkungen des Untersetzungsgetriebe dieser Ausführungsform>

[0071] In the reduction gear 10 of this embodiment, a recess 45 is formed on the axially outwardly facing end face of the transmission gear 40. The end of the input shaft (crankshaft 14) of the reduction mechanism 35 and the engagement section of the retaining ring 48 (stop element) are housed in the recess 45. Therefore, the axially outward end of the input shaft (crankshaft 14) does not project further outwards than the transmission gear 40.

[0072] Furthermore, in the reduction gear 10 of this embodiment, a recess 45 is formed on the end face of the transmission gear 40, which fulfills both conditions (condition 1) and (condition 2). Therefore, when the input gear 30 and the transmission gear 40 mesh to transmit power, the meshing force acting between them is stably absorbed by the splined engagement section between the crankshaft 14 and the transmission gear 40. Thus, during operation of the reduction gear 10, the wobble of the transmission gear 40 is suppressed.

[0073] As a result, when using the reduction gear 10 of this embodiment, it is possible to shorten the axial length of the input shaft of the reduction mechanism 35 and at the same time minimize the generation of vibration noise during operation.

[0074] Fig. Figure 5 shows a cross-section (a) of the transmission gear 40 that satisfies both conditions (condition 1) and (condition 2), and a cross-section (b) of the transmission gear 40' that does not satisfy both conditions (condition 1) and (condition 2).

[0075] The cross-section (a) in Fig. The transmission gear 40 shown in Figure 5 has a recess 45 designed such that the tooth width w2 of the splines of the input shaft (crankshaft 14) and the transmission gear 40 is 60% of the tooth width w1 of the transmission gear 40. The axially orthogonal plane S1, which passes through the axial center ac of the tooth width w1 of the transmission gear 40, lies within the area of ​​the tooth width w2.

[0076] The cross-section (b) in Fig. The transmission gear 40' shown in Figure 5 has a recess 45 designed such that the tooth width w2' of the splines of the input shaft (crankshaft 14) and the transmission gear 40' is 50% of the tooth width w1 of the transmission gear 40'. However, the axially orthogonal plane S1, which passes through the axial center ac of the tooth width w1 of the transmission gear 40', lies outside the area of ​​the tooth width w2'.

[0077] A noise test was carried out under the same conditions on a reduction gearbox with the cross-section (a) in Fig. 5 was equipped with the transmission gear 40 shown, as well as with a reduction gear which is connected to the cross-section (b) shown in Fig. The transmission gear shown in section 5 was 40'.

[0078] When using the cross-section (a) in Fig. The noise generated by the transmission gear 40 shown in Figure 5 was 73.5 dBA. In contrast, the noise generated was 75 dBA when using the gear shown in cross-section (b) in Figure 5. Fig. 5 shown transmission gear 40.

[0079] When using the transmission gear 40 of this embodiment, which has a cross-section (a) in Fig. As shown in Figure 5, the stiffness of the comb section with the input gear 30 increased by about 10 to 15%, and the noise level improved by about 1.0 to 2.0 dBA, compared with the use of the transmission gear 40' of the comparison example, which is shown in cross-section (b) in Fig. 5 is shown.

[0080] As can be seen from the noise test results described above, the generated noise can be reduced to a level that is not disturbing to the operator if the recess 45 of the transmission gear 40 is designed to meet both conditions (Condition 1) and (Condition 2). Conversely, if the recess 45 is designed with specifications that do not meet both conditions (Condition 1) and (Condition 2), the generated noise cannot be reduced to a level that is not disturbing to the operator.

[0081] Furthermore, the reduction gear 10 of this embodiment uses an eccentrically oscillating reduction mechanism 35, wherein the crankshaft 14 is mounted in a position that is offset from the center of rotation (axis O1) of the support (first support block 13A and second support block 13B).

[0082] Furthermore, the transmission gear 40 in the reduction gear 10 rotates in meshed position with the input gear 30 while pivoting around the center of rotation of the support. Therefore, when transmitting torque, a complex torque from various directions acts on the transmission gear 40 due to changes in the output of the drive source, etc., causing the transmission gear 40 to tend towards a pivoting motion.

[0083] According to the reduction gear 10 of this embodiment, the recess 45 on the end face of the transmission gear 40 is designed to fulfill both conditions (condition 1A) and (condition 1B). Therefore, the axial length of the crankshaft 14 can be reduced, while the vibration noise caused by the wobbling behavior of the transmission gear 40 is effectively suppressed.

[0084] It should be noted that the present invention is not limited to the embodiment described above, and that various modifications are possible, provided that the core of the invention is not departed from. For example, the reduction gear 10 of this embodiment comprises two rocker gears (first rocker gear 15A and second rocker gear 15B); however, the number of rocker gears can also be one, three, or more.

[0085] Furthermore, in the embodiment described above, the retaining ring 48 is used as a stop element for axially securing the transmission gear 40 to the end of the input shaft (crankshaft 14); however, the stop element is not limited to a retaining ring. Other types of components, such as pins, can also be used as stop elements, provided they axially secure the transmission gear 40 to the input shaft (crankshaft 14).

[0086] In the embodiment described above, the side of the housing 11 of the reduction gear 10 is attached to a base, and the supports (first support block 13A and second support block 13B) are rotatably designed as output rotating bodies. Conversely, however, the support side of the reduction gear 10 can also be attached to the base, while the side of the housing 11 serves as the output rotating body.

[0087] Furthermore, the reduction gear 10 is used in the drive unit of the industrial robot 100 in the embodiment described above; however, its application is not limited to the drive unit of the industrial robot 100. The reduction gear 10 can also be used in the drive units of various other devices, such as machine tools.

[0088] Furthermore, in the embodiments disclosed in this description, parts consisting of several components can be combined into a single component, and conversely, parts consisting of a single component can be divided into several components. Whether integrated or not, it is sufficient that they are configured in such a way as to achieve the objective of the invention. Reference symbol list

[0089] 10 ... reduction gear, 11 ... housing, 13A ... first support block (carrier), 13B ... second support block (carrier), 14 ... crankshaft (input shaft), 15A ... first oscillating gear (oscillating gear), 15B ... second oscillating gear (oscillating gear), 30 ... input gear, 35 ... reduction mechanism, 40 ... transmission gear, 45 ... recess, 48 ​​... retaining ring (stop elements), ac ... axial center, S1 ... axially orthogonal plane, w1 ... tooth width, w2 ... spline width QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] JP 2014-92249

[0009]

Claims

[1] Reduction gear, comprising: a reduction mechanism with an input shaft that reduces the rotation introduced into the input shaft and outputs it; and a transmission gear which, in the engaged state, is in contact with one end of the input shaft via splined teeth and is secured in the axial direction by a stop element, wherein the transmission gear meshes with an input gear driven by a drive source in order to transmit the drive force from the input gear to the input shaft, wherein a recess is provided on the axially outwardly directed outer end face of the transmission gear, which receives the end of the input shaft and the engagement section of the stop element, wherein the recess is designed to satisfy two conditions, namely a condition in which the comb width of the splines of the input shaft and the transmission gear is 60% or more of the tooth width of the transmission gear, and the other condition in which the axially orthogonal plane passing through the axial center of the tooth width of the transmission gear lies within the area of ​​the comb width of the splines of the input shaft and the transmission gear. [2] Reduction gear, comprising a housing with internal teeth on the inner circumference; a support which is rotatably held in the housing; a crankshaft which is rotatably mounted through the support, wherein an eccentric section of the crankshaft pivots under the influence of an externally acting rotational force; a rocker gear with an external toothing that meshes with the internal toothing, wherein the external toothing has a fewer number of teeth than the internal toothing, and wherein the rocker gear rotates in an oscillating manner under the influence of the pivoting force from the eccentric section of the crankshaft and transmits the output rotation to the carrier; and a transmission gear which, in the engagement state, is in contact with one end of the crankshaft via splined teeth and is secured in the axial direction by a stop element, wherein the transmission gear meshes with an input gear driven by a drive source in order to transmit the driving force from the input gear to the crankshaft. wherein a recess is provided on the axially outwardly directed outer end face of the transmission gear, which receives the end of the crankshaft and the engagement section of the stop element, wherein the recess is designed to satisfy two conditions, namely a condition in which the comb width of the splines of the crankshaft and the transmission gear is 60% or more of the tooth width of the transmission gear, and the other condition in which the axially orthogonal plane passing through the axial center of the tooth width of the transmission gear lies within the area of ​​the comb width of the splines of the crankshaft and the transmission gear.

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