Gear system

Abstract

To restrain an increase in size of a combination of a gear device and a rotation detector.SOLUTION: A gear device comprises an internal gear 22 provided in a casing 24, external gears 20A and 20B engaged with the internal gear 22, a first carrier 26A provided on one side in an axial direction with respect to the external gears 20A and 20B, a first main bearing 28A arranged between the casing 24 and the first carrier 26A, and a first rotation detector 52A for detecting rotation of the first carrier 26A or the casing 24. The first rotation detector 52A is arranged between the first main bearing 28A and the internal gear 22.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a gear device.

Background Art

[0002] Patent Document 1 discloses a gear device including an auxiliary rotation shaft arranged in parallel with the output shaft of the gear device, a rotation transmission means for transmitting the rotation of the output shaft to the auxiliary rotation shaft, and a rotation detector for detecting the rotation of the auxiliary rotation shaft. In the disclosed technology of Patent Document 1, in order to attach the rotation detector outside the casing of the gear device, a pulley case and an encoder case are provided separately from the gear device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the disclosed technology of Patent Document 1, the rotation of an auxiliary rotation shaft offset from the output shaft is detected by a rotation detector outside the casing of the gear device. Therefore, the combination of the gear device and the rotation detector tends to be enlarged.

[0005] One object of the present disclosure is to suppress the enlargement of the combination of the gear device and the rotation detector.

Means for Solving the Problems

[0006] The gear apparatus of the present disclosure comprises an internal gear provided on a casing, an external gear meshing with the internal gear, a first carrier provided on one axial side with respect to the external gear, a first main bearing disposed between the casing and the first carrier, and a first rotation detector for detecting the rotation of the first carrier or the casing, wherein the first rotation detector is disposed between the first main bearing and the internal gear. [Effects of the Invention]

[0007] According to this disclosure, it is possible to suppress the increase in size of the combination of gear mechanism and rotation detector. [Brief explanation of the drawing]

[0008] [Figure 1] This is a side cross-sectional view of the gear device of the first embodiment. [Figure 2] This is an enlarged view of Figure 1. [Figure 3] This is a cross-sectional view AA in Figure 1. [Figure 4] This figure is a version of Figure 2 with the rotation detector omitted. [Figure 5] Figure 5(A) is a schematic diagram showing the first and second carriers rotating under no load, and Figure 5(B) is a schematic diagram showing the first and second carriers rotating under load. [Figure 6] This is a block diagram showing some functional blocks of a gear mechanism according to the first embodiment. [Figure 7] Figure 7(A) is a schematic diagram showing a part of the gear system of the first embodiment, Figure 7(B) is a schematic diagram showing a part of the gear system of the second embodiment, Figure 7(C) is a schematic diagram showing a part of the gear system of the third embodiment, and Figure 7(D) is a schematic diagram showing a part of the gear system of the fourth embodiment. [Figure 8] This is another schematic diagram showing the first and second carriers rotating under load in the deformed configuration. [Modes for carrying out the invention]

[0009] Embodiments are described below. The same reference numerals are used for identical components, and redundant descriptions are omitted. For the sake of clarity, components are omitted, enlarged, or reduced in each drawing as appropriate. Drawings should be viewed in accordance with the orientation of the reference numerals. In this specification, "fixed," "contact," and "connected" include cases where the two parties directly satisfy the conditions mentioned, as well as cases where they satisfy the conditions through other members, unless otherwise specified.

[0010] (First Embodiment) Refer to Figure 1. The gear device 10 is mainly characterized by its connection to the rotation detectors 52A and 52B, but the surrounding structure will be explained first. In this specification, the direction along the center line CL1 of the first main bearing 28A, which will be described later, is referred to as the "axial direction," and the radial and circumferential directions with the center line CL1 as the center of the circle are referred to as the "radial direction" and "circumferential direction," respectively.

[0011] The gear device 10 comprises an input member 12 to which rotation is input from a drive source, a gear mechanism 14 that changes the speed of rotation of the input member 12, and an output member 16 that outputs the output rotation taken from the gear mechanism 14 to the driven member to be driven. The drive source is, for example, a motor, gear motor, engine, etc. The specific example of the driven member is not particularly limited. The driven member may be, for example, a part of a driven machine such as a conveyor, machine tool, or wheel. In addition, the driven member may be, for example, an arm member of a multi-joint arm.

[0012] In this embodiment, the driven member that is subjected to the load is positioned on one axial side (left side in the figure) relative to the gear mechanism 14. For the sake of explanation, in this specification, the axial side will be described as the load side and the other axial side (right side in the figure) as the non-load side, but the position of the driven member is not particularly limited. The driven member may be positioned on the other axial side relative to the gear mechanism 14, or it may be positioned to overlap the gear mechanism 14 radially.

[0013] The gear mechanism 14 in this embodiment is an eccentric oscillating gear mechanism. This gear mechanism 14 comprises external gears 20A, 20B and internal gear 22 that mesh with each other, with one of them being an oscillating gear 18. This gear mechanism 14 can rotate one of the external gears 20A, 20B and internal gear 22 with the oscillation of the oscillating gear 18, and transmit the rotational component as output rotation to the output member 16. In this embodiment, the external gears 20A and 20B become the oscillating gear 18, and the external gears 20A and 20B are rotatable. The gear mechanism 14 in this embodiment functions as a reduction mechanism that reduces the rotation of the input member 12 before transmitting it to the output member 16.

[0014] In addition, the gear unit 10 includes a casing 24 that houses the gear mechanism 14, carriers 26A and 26B provided axially laterally to the external gears 20A and 20B of the gear mechanism 14, and main bearings 28A and 28B positioned between the casing 24 and the carriers 26A and 26B. The details of each component will be described below.

[0015] In this embodiment, the input member 12 is a crankshaft 30 that passes through the oscillating gear 18 in the axial direction. The crankshaft 30 includes at least one eccentric body 32 that oscillates the oscillating gear 18. The axis CL2 of the eccentric body 32 is eccentric with respect to the rotational centerline CL3 of the crankshaft 30. In this embodiment, the at least one eccentric body 32 is provided as multiple (specifically two) eccentric bodies 32. The eccentric phases of the multiple eccentric bodies 32 are shifted by 360° / M when the number of eccentric bodies 32 is M. The number of eccentric bodies 32 is not particularly limited and may be one or three or more.

[0016] The external gears 20A and 20B (oscillating gears 18) are individually provided corresponding to each of the multiple eccentric bodies 32 and are supported via eccentric body bearings 34 so as to be rotatable relative to the corresponding eccentric body 32. The external gears 20A and 20B include a first external gear 20A positioned on the load side and a second external gear 20B positioned on the non-load side.

[0017] The internal gear 22 is provided on the inner peripheral portion of the casing 24. The internal gear 22 of the present embodiment includes a gear body 22a integrated with the casing 24 and a plurality of pin members 22b provided separately from the gear body 22a and constituting the internal teeth of the internal gear 22. The pin members 22b are rotatably supported by pin grooves 22c provided on the inner peripheral portion of the gear body 22a.

[0018] The carriers 26A and 26B include a first carrier 26A disposed on the load side with respect to the external gears 20A and 20B, and a second carrier 26B disposed on the anti-load side with respect to the external gears 20A and 20B. The carriers 26A and 26B support the crankshaft 30 via support bearings 35. The carriers 26A and 26B penetrate the external gears 20A and 20B and are integrated with pin bodies 36 for synchronizing with the rotation components of the external gears 20A and 20B. Here, "synchronizing with the rotation components" means maintaining the rotation components of the external gears 20A and 20B and the carriers 26A and 26B to be the same magnitude within a numerical range including zero. The pin body 36 of the present embodiment connects the first carrier 26A and the second carrier 26B.

[0019] The main bearings 28A and 28B include a first main bearing 28A disposed between the casing 24 and the first carrier 26A, and a second main bearing 28B disposed between the casing 24 and the second carrier 26B. The first main bearing 28A allows relative rotation between the casing 24 and the first carrier 26A. The second main bearing 28B allows relative rotation between the casing 24 and the second carrier 26B. The main bearings 28A and 28B of the present embodiment are angular bearings. Specific examples of the main bearings 28A and 28B are not particularly limited, and may be tapered roller bearings, cylindrical roller bearings, ball bearings, cross roller bearings, etc.

[0020] The main bearings 28A and 28B comprise an outer ring 38 and an inner ring 40, and rolling elements 42 that roll on the outer ring 38 and the inner ring 40. In this embodiment, the main bearings 28A and 28B have a dedicated outer ring 38 that is separate from the casing 24. Alternatively, the main bearings 28A and 28B may not have a dedicated outer ring 38, and the casing 24 may also serve as the outer ring 38. In this embodiment, the main bearings 28A and 28B do not have a dedicated inner ring 40, and the carriers 26A and 26B serve as the inner ring 40. Alternatively, the main bearings 28A and 28B may also have a dedicated inner ring 40 that is separate from the carriers 26A and 26B.

[0021] In this embodiment, the output member 16 is the first carrier 26A, and the driven member is connected to the output member 16. In this case, the casing 24 is fixed to the fixed member located outside the gear unit 10.

[0022] Furthermore, a first oil seal 44A is positioned between the casing 24 and the first carrier 26A on the side opposite to the internal gear (in the axial direction, opposite to the internal gear 22) relative to the first main bearing 28A. Also, a second oil seal 44B is positioned between the casing 24 and the second carrier 26B on the side opposite to the internal gear relative to the second main bearing 28B. The oil seals 44A and 44B seal the enclosed space into which the lubricant for lubricating the gear mechanism 14 is contained.

[0023] The operation of the gear device 10 described above will now be explained. When rotation is input from the drive source to the input member 12, the gear mechanism 14 is activated. When the gear mechanism 14 is activated, the output rotation, which has been speed-shifted in relation to the rotation of the input member 12, is taken out from the gear mechanism 14 through the output member 16. In this embodiment, when the input member 12 rotates, the meshing positions of the external gears 20A, 20B and the internal gear 22 change sequentially in the circumferential direction, accompanied by the oscillation of the oscillating gear 18. As a result, the external gears 20A and 20B rotate on their own, and the component of that rotation is taken out from the output member 16 as output rotation.

[0024] Refer to Figure 2. We will now move on to the description of the rotation detectors 52A and 52B. The gear device 10 includes a first rotation detector 52A that detects the rotation of the first rotating member 50A, and a second rotation detector 52B that detects the rotation of the second rotating member 50B. The first rotating member 50A is either the first carrier 26A or the casing 24, and in this embodiment it is the first carrier 26A. The second rotating member 50B is either the second carrier 26B or the casing 24, and in this embodiment it is the second carrier 26B. Hereinafter, the other of the first carrier 26A or the casing 24 will be referred to as the first fixed member 54A, and the other of the second carrier 26B or the casing 24 will be referred to as the second fixed member 54B. In this embodiment, both the first fixed member 54A and the second fixed member 54B are the casing 24.

[0025] The first rotation detector 52A is positioned between the first main bearing 28A and the internal gear 22. In this embodiment, the first rotation detector 52A is positioned between the first main bearing 28A and the pin member 22b of the internal gear 22. The second rotation detector 52B is positioned between the second main bearing 28B and the internal gear 22. In this embodiment, the second rotation detector 52B is positioned between the second main bearing 28B and the pin member 22b of the internal gear 22.

[0026] The following describes the features common to the first rotation detector 52A and the second rotation detector 52B. This common configuration will be explained using Figure 3, which shows the first rotation detector 52A, in addition to Figure 2. In Figures 2 and 3, for the sake of clarity, hatching is applied only to the areas of the carriers 26A and 26B that constitute the detected section 60 (described later).

[0027] The rotation detectors 52A and 52B in this embodiment are magnetic encoders. The rotation detectors 52A and 52B comprise a detection unit 60 integrated with the rotating members 50A and 50B (here, the carriers 26A and 26B), and a detection unit 62 fixed to the fixing members 54A and 54B (here, the casing 24). In this embodiment, the detection unit 62 is radially opposed to the detection unit 60 with a gap between them. The detection unit 62 is fixed to the fixing members 54A and 54B using fasteners such as screw members 61.

[0028] In this embodiment, the detection unit 62 is an encoder head. The detection unit 62 includes a sensor 64 capable of detecting a predetermined physical quantity (e.g., magnetic field, light intensity, etc.). The detected unit 60 can change the physical quantity detected by the sensor 64 when the rotating members 50A and 50B rotate. The detection unit 62 can detect the rotation of the rotating members 50A and 50B by detecting the physical quantity that changes due to the detected unit 60 in this way. In other words, the detection unit 62 can detect the rotation of the rotating members 50A and 50B in cooperation with the detected unit 60.

[0029] For example, if the rotation detectors 52A and 52B are magnetic encoders, the sensor 64 becomes a magnetic sensor capable of detecting magnetic fields, and the detected part 60 becomes a magnetic scale with N poles and S poles arranged alternately in the circumferential direction. The detected part 60, composed of the magnetic scale, can change the magnetic field detected by the sensor 64 when the rotating members 50A and 50B rotate. The detection unit 62 can detect the rotation of the rotating members 50A and 50B by detecting the magnetic field that changes due to the detected part 60 using the sensor 64.

[0030] The detected portion 60, which is composed of a magnetic scale, is integrated with the rotating members 50A and 50B. In this embodiment, the detected portion 60 is integrated with the outer circumference of the rotating members 50A and 50B (here, the carriers 26A and 26B). In this embodiment, the detected portion 60 is integrally molded as part of the rotating members 50A and 50B for integration with them. To achieve this, the rotating members 50A and 50B may be made of a ferromagnetic material such as ferrite, and the magnetic pattern constituting the magnetic scale (detected portion 60) may be magnetized using a magnetizer. Alternatively, the detected portion 60 may be provided separately from the rotating members 50A and 50B for integration with them. To achieve this, a ring on which the magnetic scale is provided may be attached to the rotating members 50A and 50B.

[0031] The detection unit 62 processes the sensor signal generated by the sensor 64 and, as a result of the detection, can acquire a detection signal indicating the rotational state (rotation angle, etc.) of the rotating members 50A and 50B. The method for processing the sensor signal to achieve this is not particularly limited, and various known processing methods may be adopted. For example, the detection unit 62 may acquire either the relative rotation angle or the absolute rotation angle of the rotating members 50A and 50B. The detection unit 62 can output the acquired detection signal to an external information processing device (here, the calculation unit 84, which will be described later). In this embodiment, these functions of the detection unit 62 are realized by hardware such as a CPU built into the housing of the encoder head that constitutes the detection unit 62.

[0032] The gear unit 10 is equipped with wiring 66 connected to the detection unit 62. The detection signal from the detection unit 62 is transmitted to an external information processing device through the wiring 66. The wiring 66 is led out of the casing 24 through a wiring hole 68 formed in the casing 24.

[0033] Furthermore, the casing 24 includes a first casing housing section 69A for housing the first rotation detector 52A and a second casing housing section 69B for housing the second rotation detector 52B. The casing housing sections 69A and 69B are provided so as to be recessed radially outward on the inner circumference of the casing 24. Parts of the rotation detectors 52A and 52B, and in this embodiment, part of their detection section 62, are housed in the casing housing sections 90A and 90B. The detection section 62 is placed against the side surface of the casing housing sections 69A and 69B on the internal gear side and fixed to that side surface by a fixing device such as a screw member 61. The screw member 91 passes through the detection section 62 in the axial direction and its tip is screwed into the casing 24.

[0034] Refer to Figures 2 to 4. The gear mechanism 10 includes a first regulating member 70A that overlaps with the first rotation detector 52A in the axial position, and a second regulating member 70B that overlaps with the second rotation detector 52B in the axial position. Here, "overlapping in the axial position" means that the axial positions of the rotation detectors 52A, 52B and the regulating members 70A, 70B mentioned are at least partially overlapping. The features common to the first regulating member 70A and the second regulating member 70B will be described below.

[0035] The regulating members 70A and 70B in this embodiment are ring-shaped. The regulating members 70A and 70B are provided at locations that overlap with the rotation detectors 52A and 52B in the axial position, and include a detector housing 72 that accommodates the rotation detectors 52A and 52B. The detector housing 72 in this embodiment is composed of a notch that cuts out the regulating members 70A and 70B. This notch penetrates the regulating members 70A and 70B radially and is open toward the side opposite the internal gear.

[0036] The restricting members 70A and 70B contact the main bearings 28A and 28B from the internal gear side (the side with the internal gear 22 in the axial direction), thereby restricting the axial movement of the main bearings 28A and 28B toward the internal gear side. To achieve this, the restricting members 70A and 70B in this embodiment contact the outer ring 38 of the main bearings 28A and 28B from the internal gear side. In this embodiment, the first restricting member 70A contacts the first main bearing 28A directly, and the second restricting member 70B contacts the second main bearing 28B via the ring-shaped first spacer 74.

[0037] Furthermore, the axial movement of the main bearings 28A and 28B toward the carriers 26A and 26B is restricted by contacting them from the side opposite to the internal gear. In this embodiment, the rolling elements 42 of the main bearings 28A and 28B contact the carriers 26A and 26B from the side opposite to the internal gear. In other words, the movement of the main bearings 28A and 28B toward both sides is restricted by contact from both sides in the axial direction by the restricting members 70A and 70B and the carriers 26A and 26B.

[0038] The first restricting member 70A restricts the axial movement of the pin member 22b of the internal gear 22 toward the load side by contacting it from the load side (left side in Figure 2). The first restricting member 70A functions as a spacer to maintain the distance between the pin member 22b and the first main bearing 28A by contacting both the first main bearing 28A and the pin member 22b. The second restricting member 70B restricts the axial movement of the pin member 22b toward the non-load side by contacting it from the non-load side (right side in Figure 2). The second restricting member 70B functions as a spacer to maintain the distance between the pin member 22b and the second main bearing 28B by contacting both the second main bearing 28B and the pin member 22b. In this embodiment, the movement of the pin member 22b toward both sides of the axial direction is restricted by contact from both sides of the first restricting member 70A and the second restricting member 70B.

[0039] The first restricting member 70A restricts the axial movement of the first external gear 20A toward the load side by contacting the first external gear 20A from the load side. The first restricting member 70A functions as a spacer that maintains the distance between the external gears 20A, 20B and the first main bearing 28A by contacting the first main bearing 28A and each of the external gears 20A and 20B. The second restricting member 70B restricts the axial movement of the second external gear 20B toward the non-load side by contacting the second external gear 20B from the non-load side. The second restricting member 70B functions as a spacer that maintains the distance between the external gears 20A, 20B and the second main bearing 28B by contacting the second main bearing 28B and each of the external gears 20A and 20B. The external gears 20A and 20B located between the first restricting member 70A and the second restricting member 70B have their axial movement restricted on both sides by the contact between the first restricting member 70A and the second restricting member 70B from both sides in the axial direction. Adjacent external gears 20A and 20B make contact via a ring-shaped second spacer 76 positioned between them.

[0040] The effects of the gear mechanism 10 described above will now be explained.

[0041] The gear unit 10 includes a first rotation detector 52A positioned between the first main bearing 28A and the internal gear 22. This means that the first rotation detector 52A is located inside the casing 24 of the gear unit 10. Therefore, compared to the case where the first rotation detector 52A is positioned outside the casing 24 of the gear unit 10, the overall size of the gear unit 10 and the rotation detector 52A combination (especially in the radial direction) can be reduced. Furthermore, if a customer who has purchased only the gear unit 10 wishes to use the first rotation detector 52A, they will not need to design the mounting of the rotation detectors 52A and 52B outside the casing 24. In short, this reduces the effort required from the customer when using the first rotation detector 52A.

[0042] Furthermore, since the customer does not need to design for the use of the first rotation detector 52A, the costs required on the customer's side can be reduced. Also, if the first rotation detector 52A is placed outside the casing 24 of the gear unit 10 separately from the gear unit 10, the customer who purchased only the gear unit 10 will need to calibrate the first rotation detector 52A in order to use it. In this respect, since the first rotation detector 52A in this embodiment is incorporated into the gear unit 10, the manufacturer can calibrate the first rotation detector 52A, eliminating the need for the customer to perform calibration.

[0043] The gear unit 10 is equipped with a first main bearing 28A and a second main bearing 28B, and the first rotation detector 52A is positioned between the first main bearing 28A and the internal gear 22. Therefore, compared to the case without the first rotation detector 52A, the bearing span La (see Figure 1) between the pair of main bearings 28A and 28B can be widened, and the bearing rigidity of the main bearings 28A and 28B can be increased. Here, the bearing span La refers to the distance between the points of action Pa of the first main bearing 28A and the second main bearing 28B, as shown in Figure 1. Here, the point of action Pa refers to the intersection of the lines of action Lb of the main bearings 28A and 28B and the center line CL1.

[0044] The gear unit 10 includes a second rotation detector 52B positioned between the second main bearing 28B and the internal gear 22. Therefore, compared to the case without the second rotation detector 52B, the bearing span La between the pair of main bearings 28A and 28B can be further widened, and the bearing rigidity of the main bearings 28A and 28B can be further increased. In addition, by providing a second rotation detector 52B in addition to the first rotation detector 52A, redundancy can be provided with respect to the rotation detection function.

[0045] The restricting member 70A restricts the axial movement of the first main bearing 28A. Therefore, the restricting member 70A prevents the first main bearing 28A from hitting the first rotation detector 52A.

[0046] The restricting member 70A restricts the axial movement of the pin member 22b. Therefore, the restricting member 70A prevents the pin member 22b from hitting the first rotation detector 52A.

[0047] The restricting member 70A restricts the axial movement of the external gear 20A. Therefore, the restricting member 70A prevents the external gear 20A from hitting the first rotation detector 52A.

[0048] In this way, the restricting member 70A prevents the first main bearing 28A, etc. from hitting the first rotation detector 52A (in this embodiment, the detection unit 62 of the first rotation detector 52A), thereby preventing misalignment of the first rotation detector 52A. Consequently, by preventing misalignment of the first rotation detector 52A, the detection accuracy of the first rotation detector 52A can be ensured.

[0049] Next, other features of the gear unit 10 will be described. Refer to Figure 5. Figures 5(A) and 5(B) show each carrier 26A and 26B rotating in the rotational direction Da. Each carrier 26A and 26B has reference points A and B to determine its position in the rotational direction Da.

[0050] Figure 5(A) shows the state in which the first carrier 26A and the second carrier 26B are rotating under no-load conditions, where no rotational load L is acting on the first carrier 26A, which is the output member 16. The no-load condition is achieved when the driven member that applies the rotational load L to the first carrier 26A is not connected to the first carrier 26A. The difference between the rotation angle θA of the first carrier 26A and the rotation angle θB of the second carrier 26B is defined as the rotation angle difference φ (= θA - θB), and the rotation angle difference φ when under no-load conditions is defined as the initial rotation angle difference φ0. Here, the rotation angles θA and θB refer to the amount of rotation from the reference rotation position. In the example in Figure 5(A), both the first carrier 26A and the second carrier 26B are at the reference rotation position where the rotation angles θA and θB are zero, and the initial rotation angle difference φ0 is zero.

[0051] Figure 5(B) shows the state in which the first carrier 26A and the second carrier 26B are rotating under a load condition in which a rotational load L is acting on the first carrier 26A. The load condition is achieved when a driven member is connected to the first carrier 26A. Here, an example is shown in which the rotational force transmitted from the drive source via the gear mechanism 14 is output from the first carrier 26A to the driven member. At this time, the rotational reaction force transmitted from the driven member to the first carrier 26A acts on the first carrier 26A as a rotational load L. When under load, the rotational load L acting on the first carrier 26A causes the first carrier 26A and the pin body 36 to undergo elastic twisting deformation in the circumferential direction. When the rotational reaction force acts on the first carrier 26A as a rotational load L, the first carrier 26A undergoes twisting deformation such that its rotation angle lags behind that of the second carrier 26B compared to when it is unloaded. As a result, the difference in rotational angle φ between the first carrier 26A and the second carrier 26B when under load changes by an amount of change Δφ compared to the initial difference in rotational angle φ0 when under no load. In the example in Figure 5(B), since the initial difference in rotational angle φ0 is zero, the difference in rotational angle φ when under load is the amount of change Δφ itself.

[0052] The change in rotational angle difference φ, Δφ, increases as the rotational load L acting on the first carrier 26A increases. In other words, there is a positive correlation (for example, a linear relationship) between the rotational load L acting on the first carrier 26A and the change in Δφ. Therefore, by pre-determining the correspondence between the rotational load L and the change in Δφ, the rotational load L acting on the first carrier 26A can be calculated using the change in Δφ. In the gear device 10 of this embodiment, this approach is used to devise a method for calculating the rotational load L acting on the first carrier 26A. The details are described below.

[0053] Refer to Figure 6. Figure 6 is a block diagram showing some of the functional blocks of the gear mechanism 10. Each block shown in the block diagram can be realized hardware-wise by electronic components such as a computer's CPU (Central Processing Unit), circuits, mechanical devices, etc., and software-wise by computer programs, etc. Here, we depict the functional blocks realized through the cooperation of these. It will be understood by those skilled in the art that these functional blocks can be realized in various ways by combinations of hardware and software.

[0054] The gear unit 10 includes a first storage unit 80 that stores the initial rotation angle difference φ0 of the first carrier 26A and the second carrier 26B when there is no load. The initial rotation angle difference φ0 can be determined by the difference between the rotation angle θA of the first carrier 26A detected by the first rotation detector 52A and the rotation angle θB of the second carrier 26B detected by the second rotation detector 52B when there is no load. The rotation angles θA and θB of these carriers 26A and 26B are determined using detection signals detected by the rotation detectors 52A and 52B at the same timing when the first carrier 26A and the second carrier 26B are rotating in the no-load state.

[0055] The gear unit 10 includes a second storage unit 82 that stores a relational expression or relational table that defines the correspondence between the rotational load L acting on the first carrier 26A and the change in rotational angle difference φ Δφ. This relational expression or relational table can be determined in advance by experiment or analysis and then stored in the second storage unit 82.

[0056] The gear unit 10 includes a calculation unit 84 that calculates the rotational load L acting on the first carrier 26A based on the detection results of the first rotation detector 52A and the second rotation detector 52B. As described below, the calculation unit 84 calculates the rotational angle difference φ of the first carrier 26A and the second carrier 26B based on the detection results of the rotation detectors 52A and 52B, and calculates the rotational load L based on the calculated rotational angle difference φ. The flow of the calculation process for calculating this rotational load L will be explained below.

[0057] When the first carrier 26A and the second carrier 26B are rotating under load, the calculation unit 84 calculates the rotation angle difference φ between the first carrier 26A and the second carrier 26B using the detection results of the first rotation detector 52A and the second rotation detector 52B (S10). This can be determined, for example, by the difference between the rotation angle θA of the first carrier 26A detected by the first rotation detector 52A and the rotation angle θB of the second carrier 26B detected by the second rotation detector 52B, as described above. The rotation angles θA and θB of these carriers 26A and 26B are also determined using the detection signals detected by the rotation detectors 52A and 52B at the same timing when the first carrier 26A and the second carrier 26B are rotating under load.

[0058] Next, the calculation unit 84 reads the initial rotation angle difference φ0 stored in the first storage unit 80 and calculates the change in rotation angle difference φ, which is the difference (=φ-φ0) between the rotation angle difference φ calculated in S10 and the initial rotation angle difference φ0 (S12).

[0059] Next, the calculation unit 84 refers to the relational expression or relational table stored in the second storage unit 82 and calculates the rotational load L acting on the first carrier 26A based on the calculated change in rotational angle difference φ Δφ (S14). The rotational load L may be calculated, for example, as either the torque or load acting on the first carrier 26A. The rotational load L is calculated by going through the above series of calculation processes.

[0060] The memory units 80, 82 and the calculation unit 84 described above may be built into the housing of one of the encoder heads that constitute the detection unit 62. In addition, the memory units 80, 82 and the calculation unit 84 may be mounted separately from the detection unit 62 as part of the gear mechanism (for example, the casing 24).

[0061] The gear unit 10 can determine the rotational load L acting on the first carrier 26A using the calculation unit 84 described above. The gear unit 10 may also include a motor control unit that controls the motor that is the drive source of the gear unit 10 using the rotational load L thus determined. The motor control unit may, for example, detect contact of an obstacle (e.g., a person) with the driven member based on the calculated rotational load L and stop the motor. In addition, the motor control unit may control the motor to apply a predetermined pressing force to an external member via the driven member based on the calculated rotational load L.

[0062] (Second to Fourth Embodiments) Figure 7(A) shows a schematic diagram of the main bearings 28A, 28B and rotation detectors 52A, 52B used in the gear unit 10 of the first embodiment. As shown in Figure 7(B), the gear unit 10 may be equipped with only the first rotation detector 52A. Thus, the number of rotation detectors 52A, 52B used in the gear unit 10 is not particularly limited, and there may be three or more of them.

[0063] In addition, as shown in Figure 7(C), the first rotation detector 52A may also include a plurality of detection units 62 that are spaced apart in the circumferential direction. Each of the plurality of detection units 62 can detect the rotation of the first rotating member 50A (first carrier 26A) by detecting a physical quantity that changes due to a common detected unit 60 when the first rotating member 50A rotates.

[0064] In addition, as shown in Figure 7(D), the second rotation detector 52B may also be equipped with a plurality of detection units 62 that are spaced apart in the circumferential direction, similar to the first rotation detector 52A. Each of the plurality of detection units 62 can detect the rotation of the second rotation member 50B by detecting a physical quantity that changes due to a common detected unit 60 when the second rotation member 50B rotates.

[0065] As described above, when the rotation detectors 52A and 52B are equipped with multiple detection units 62, redundancy can be provided when detecting the rotation of the same rotating members 50A and 50B. In addition, the detected unit 60 can be shared among the multiple detection units 62 when detecting the rotation of the rotating members 50A and 50B. Therefore, the number of parts can be reduced compared to the case where each detection unit 62 uses its own detected unit 60. Note that the number of detection units 62 in the rotation detectors 52A and 52B is not particularly limited. The number of detection units 62 may be three or more.

[0066] Next, we will describe the transformation forms of each component described so far.

[0067] The specific examples of the gear mechanism 14 used in the gear device 10 are not particularly limited. The gear mechanism 14 may be, for example, an eccentric oscillating gear mechanism, a flexible meshing gear mechanism, a simple planetary gear mechanism, etc.

[0068] When using an eccentric oscillating gear mechanism, the type is not particularly limited. As an example, a center crank type in which the crankshaft 30 is positioned on the center line CL1 of the main bearings 28A and 28B has been described. In addition, a distribution type in which multiple crankshafts 30 are positioned radially offset from the center line CL1 of the main bearings 28A and 28B is also possible. Furthermore, when using an eccentric oscillating gear mechanism, the internal gear 22 may be replaced with an oscillating gear 18.

[0069] When using a flexible meshing gear mechanism, the specific type is not particularly limited. Examples of such types include cylindrical, cup-shaped, and top-hat-shaped gears.

[0070] The output member 16 may be a casing 24. In this case, the first carrier 26A may be fixed to a fixed member located outside the gear unit.

[0071] Up to this point, we have described an example in which the input member 12 is a high-speed member (crankshaft 30) that rotates at high speed, the output member 16 is a low-speed member (first carrier 26A) that rotates at low speed, and the gear mechanism 14 reduces the rotation input to the high-speed member and transmits it to the low-speed member. In addition to this, the input member 12 may be a low-speed member (first carrier 26A, etc.), the output member 16 may be a high-speed member (crankshaft 30, etc.), and the gear mechanism 14 increases the speed of the rotation input to the low-speed member and transmits it to the high-speed member.

[0072] Although an example has been described in which the gear body 22a and the internal teeth (pin members 22b) of the internal gear 22 are separate parts, they may also be integrally molded.

[0073] An example has been described in which the gear unit 10 comprises a pair of carriers 26A and 26B and a pair of main bearings 28A and 28B. However, the gear unit 10 is not limited to this example, and may comprise only the first carrier 26A and the first main bearing 28A, without comprising the second carrier 26B and the second main bearing 28B.

[0074] The specific examples of rotation detectors 52A and 52B are not particularly limited. Rotation detectors 52A and 52B may be, for example, optical encoders, or electromagnetic induction encoders such as resolvers.

[0075] In the case of an optical encoder, the sensor 64 is an optical sensor capable of detecting the amount of light detected, and the detected part 60 is an optical scale having a pattern that reflects or transmits the detected light emitted from the light source. The detected part 60, which is composed of an optical scale, can change the amount of light detected by the sensor 64 by allowing the detected light to pass through it when the rotating members 50A and 50B rotate. The detection unit 62 can detect the rotation of the rotating members 50A and 50B by detecting the amount of light that changes due to the detected part 60 in this way using the sensor 64.

[0076] Although an example has been described in which the detection unit 62 and the detected unit 60 face each other in the radial direction, they may also face each other in the axial direction. In this case, the detected unit 60 only needs to be integrated with the axially facing portions of the fixing members 54A and 54B.

[0077] An example was described in which the rotating members 50A and 50B are carriers 26A and 26B, and the carriers 26A and 26B of the casing 24, and the fixed members 54A and 54B are the casing 24. In other cases, the rotating members 50A and 50B may be the casing 24, and the fixed members 54A and 54B may be carriers 26A and 26B. This assumes, for example, that the casing 24 is the output member 16.

[0078] The calculation unit 84 only needs to be able to calculate the rotational load acting on the first carrier 26A based on the detection results of the first rotation detector 52A and the second rotation detector 52B, and the specific calculation procedure is not limited to the contents of the embodiment.

[0079] Refer to Figure 8. Figure 5(B) illustrates an example in which rotational force is input from the drive source to the gear unit 10, and the rotational force is output from the first carrier 26A to the driven member, and the rotational reaction force transmitted from the driven member to the first carrier 26A is calculated as the rotational load L. Alternatively, the rotational load L acting on the first carrier 26A may be calculated when rotational force is input from the driven member to the first carrier 26A. In this case, the rotational force input from the driven member to the first carrier 26A acts on the first carrier 26A as the rotational load L. In this case, when under load, the rotational load L acting on the first carrier 26A causes the first carrier 26A and the pin body 36 to undergo elastic twisting deformation in the circumferential direction so that the rotation angle of the first carrier 26A advances relative to the second carrier 26B. In this case, contact of the driven member with an obstacle can be detected based on the rotational load L calculated as described above. When the driven machine is a multi-jointed arm, contact with an obstacle by the driven member (arm member) can be detected, enabling an avoidance maneuver to move away from that obstacle.

[0080] The gear unit 10 does not need to have restricting members 70A and 70B, or it may have only one of the restricting members 70A and 70B. The restricting members 70A and 70B only need to restrict the axial movement of at least one of the following: the first main bearing 28A, the external gears 20A and 20B, and the pin member 22b. For example, the restricting members 70A and 70B do not need to restrict the axial movement of the first main bearing 28A, but do not need to restrict the axial movement of the others. Furthermore, although the external gears 20A and 20B whose axial movement is restricted by the restricting members 70A and 70B were described as being used in an eccentric oscillating gear mechanism, they may also be planetary gears used in a planetary gear mechanism.

[0081] The embodiments and variations described above are illustrative. The abstract technical ideas derived from them should not be interpreted restrictively to the content of the embodiments and variations. Many design changes are possible, such as changes, additions, and deletions of components, in the embodiments and variations. In the embodiments described above, the content that allows for such design changes is emphasized with the notation "embodiment." However, design changes are also permitted even in content without such notation. The hatching applied to the cross-sections in the drawings does not limit the material to which the hatching is applied. [Explanation of Symbols]

[0082] 10...Gear unit, 20A, 20B...External gear, 22...Internal gear, 22b...Pin member, 24...Casing, 26A...First carrier, 26B...Second carrier, 28A...First main bearing, 28B...Second main bearing, 52A...First rotation detector, 52B...Second rotation detector, 60...Detected unit, 62...Detection unit, 70A, 70B...Regulating member, 84...Calculation unit.

Claims

1. An internal gear provided in the casing, An external gear that meshes with the aforementioned internal gear, A first carrier provided on one axial side with respect to the external gear, A first main bearing is positioned between the casing and the first carrier, A gear apparatus comprising a first rotation detector for detecting the rotation of the first carrier or the casing, The first rotation detector is positioned between the first main bearing and the internal gear. The regulating member is provided which overlaps with the first rotation detector in the axial position, The restricting member is a gear device that restricts the axial movement of the first main bearing.

2. An internal gear provided in the casing, An external gear that meshes with the aforementioned internal gear, A first carrier provided on one axial side with respect to the external gear, A first main bearing is positioned between the casing and the first carrier, A gear apparatus comprising a first rotation detector for detecting the rotation of the first carrier or the casing, The first rotation detector is positioned between the first main bearing and the internal gear. The regulating member is provided which overlaps with the first rotation detector in the axial position, The restricting member is a gear device that restricts the axial movement of the pin member constituting the internal gear.

3. An internal gear provided in the casing, An external gear that meshes with the aforementioned internal gear, A first carrier provided on one axial side with respect to the external gear, A first main bearing is positioned between the casing and the first carrier, A gear apparatus comprising a first rotation detector for detecting the rotation of the first carrier or the casing, The first rotation detector is positioned between the first main bearing and the internal gear. The regulating member is provided which overlaps with the first rotation detector in the axial position, The restricting member is a gear device that restricts the axial movement of the external gear.

4. A second carrier provided on the axial side opposite to the external gear, A second main bearing is disposed between the casing and the second carrier, The gear apparatus according to any one of claims 1 to 3, wherein the first rotation detector is positioned between the first main bearing and the second main bearing in the axial direction.

5. A second rotation detector is positioned between the second main bearing and the internal gear, The gear apparatus according to claim 4, further comprising a calculation unit that calculates the rotational load acting on the first carrier based on the detection results of the first rotation detector and the second rotation detector.

6. The gear apparatus according to any one of claims 1 to 5, wherein the first rotation detector is disposed between the first main bearing and the external gear.

7. The first rotation detector is, A detection unit integrated into one of the first carrier and the casing, A gear device according to any one of claims 1 to 6, comprising: a detection unit fixed to the other of the first carrier and the casing and facing the detected unit.

8. The gear apparatus according to claim 7, wherein the first rotation detector comprises a plurality of detection units arranged apart in the circumferential direction.

Images