Gear motor

Abstract

To provide a gear motor in which loss in the gear motor can be reduced.SOLUTION: A gear motor 100 according to a certain aspect includes a motor 1 having a motor shaft 11 in which a hollow hole 111 is provided, and a reduction gear 2 having an input shaft 21 in which another hollow hole 211 is provided. A first sliding surface 113 on which a first seal member S1 is disposed is provided on a load side of the motor shaft 11. The outer diameter of the first sliding surface 113 is smaller than the outer diameter of a motor 1-side end of the input shaft 21.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a geared motor.

Background Art

[0002] A geared motor in which an input shaft of a speed reducer and a motor shaft are connected is known. The applicant discloses a geared motor having a motor and a speed reducer in Patent Document 1. In this geared motor, the motor shaft of the motor and the input shaft of the speed reducer have a hollow portion penetrating in the axial direction. A connecting member is disposed between the motor shaft and the input shaft, and these shafts and the connecting member are connected by bolts.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A geared motor composed of a motor and a speed reducer may be manufactured separately and then connected from the viewpoint of assemblability and the like. When an oil seal is provided between the motor and the speed reducer in this configuration, it is desirable that the loss of the geared motor due to this oil seal is small. In the geared motor described in Patent Document 1, an oil seal is disposed on the outer periphery of the input shaft of the speed reducer, and there is room for improvement from the viewpoint of reducing the loss of the geared motor.

[0005] The present invention has been made in view of such problems, and one of the objects is to provide a geared motor capable of reducing the loss of the geared motor.

Means for Solving the Problems

[0006] To solve the above problems, a gear motor according to one aspect of the present invention comprises a motor having a motor shaft with a hollow hole and a reduction gear having an input shaft with another hollow hole, wherein the gear motor has a first sliding surface on the load side of the motor shaft on which a first sealing member is disposed. The outer diameter of the first sliding surface is smaller than the outer diameter of the motor-side end of the input shaft.

[0007] Furthermore, any combination of the above components, or in which the components or expressions of the present invention are mutually substituted among methods, systems, etc., are also valid embodiments of the present invention. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a gear motor that can reduce losses in the gear motor. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view showing an example of a gear motor according to the embodiment. [Figure 2] This figure shows a magnified view of the area around the connection point between the motor shaft and the input shaft in Figure 1. [Modes for carrying out the invention]

[0010] The present invention will be described below with reference to the drawings, based on preferred embodiments. In embodiments and modifications, the same or equivalent components and members will be denoted by the same reference numerals, and redundant explanations will be omitted as appropriate. In addition, the dimensions of the members in each drawing will be enlarged or reduced as appropriate for ease of understanding. Furthermore, some members used to illustrate embodiments will be omitted from the drawings.

[0011] Furthermore, while terms including ordinal numbers such as "first" and "second" are used to describe various components, these terms are used solely to distinguish one component from others, and do not limit the components themselves.

[0012] [Embodiment] Referring to Figure 1, the configuration of the gear motor 100 according to the embodiment will be described. Figure 1 is a side cross-sectional view showing the gear motor 100 according to an embodiment of the present invention. Hereinafter, the direction along the central axis La of the motor shaft 11 of the motor 1, which will be described later, will be referred to as the "axial direction," and the circumferential direction and radial direction of the circle centered on the central axis La will be referred to as the "circumferential direction" and "radial direction," respectively. Also, for convenience, hereafter, one side of the axial direction (right side in the figure) will be referred to as the input side, and the other side (left side in the figure) will be referred to as the non-input side. The axial direction is indicated by arrow X.

[0013] First, the overall configuration of the gear motor 100 will be described. The gear motor 100 comprises a motor 1, a reduction gear 2, a cylindrical member 5, a functional unit 6, and a casing 7. The motor 1 inputs rotation to the reduction gear 2. The reduction gear 2 reduces the input rotation and outputs it to the driven member 81. The functional unit 6 adds predetermined functions to the gear motor 100.

[0014] The casing 7 encloses the motor 1, the gearbox 2, and the functional unit 6, and functions as their outer shell. In this example, the casing 7 is arranged in order from the non-input side to the input side as follows: first casing 71, second casing 72, third casing 73, fourth casing 74, fifth casing 75, and sixth casing 76. The first casing 71, second casing 72, and third casing 73 are connected by bolts B2-B4, the third casing 73, fourth casing 74, and fifth casing 75 are connected by bolt B5, and the fifth casing 75 and sixth casing 76 are connected by bolt B6.

[0015] (motor) Let's describe motor 1. There are no restrictions on motor 1 as long as it can output rotation to the reduction gear 2, and motors based on various principles can be used. In this embodiment, motor 1 is a brushless DC motor (sometimes called an AC servo motor). Hereafter, for convenience, the side on which the reduction gear 2, which is the load on motor 1 in the axial direction, is located will be called the load side, and the opposite side will be called the non-load side. In this example, the non-input side of motor 1 is the load side, and the input side of motor 1 is the non-load side.

[0016] Motor 1 includes a motor shaft 11, a magnet 12, a stator core 13, an armature coil 14, motor bearings 15 and 16, a second casing 72, a third casing 73, and a fourth casing 74. Various known bearing mechanisms can be used for the motor bearings 15 and 16, and in this example, deep groove ball bearings.

[0017] The motor shaft 11 is a hollow shaft having a hollow hole 111. The motor shaft 11 can be made up of one piece or multiple pieces, and when made up of multiple pieces, the motor shaft 11 also includes shaft members that are separate from the motor shaft and connected to it. The motor shaft 11 is rotatably supported by two motor bearings 15 and 16 that are spaced apart in the axial direction. On the outer circumference of the motor shaft 11, in order from the non-input side toward the input side, are a connecting portion 112, a first sliding surface 113, a first bearing support portion 114, a magnet support portion 115, a second bearing support portion 116, a disk support portion 117, an encoder support portion 118, and a second sliding surface 119.

[0018] The motor shaft 11 of motor 1 may be connected to the input shaft 21 of reduction gear 2 via an intermediary mechanism such as a coupling, but in the example shown in Figure 1, the motor shaft 11 is connected to the input shaft 21 of reduction gear 2. In this example, since they are connected directly without an intermediary mechanism, manufacturing costs and space requirements for an intermediary mechanism can be saved. In this example, the connecting portion 112 of the motor shaft 11 is the part that is connected to the input shaft 21. For example, the connecting portion 112 has a spline groove G11 (external teeth) and fits into a spline groove G21 (internal teeth) provided in the hollow hole 211 of the input shaft 21, thereby forming a spline connection.

[0019] The first sliding surface 113 has a larger diameter than the connecting portion 112, and the lip portion of the first seal member S1 abuts thereon. The first bearing support portion 114 has a larger diameter than the first sliding surface 113 and supports the inner ring of the first motor bearing 15. The magnet support portion 115 has a larger diameter than the first bearing support portion 114, and the magnet 12 is fixed thereto. The second bearing support portion 116 has the same diameter as the first bearing support portion 114 and supports the inner ring of the second motor bearing 16. The disk support portion 117 has a smaller diameter than the second bearing support portion 116, and the brake disk 63 is fixed thereto. The encoder support portion 118 has a smaller diameter than the disk support portion 117, and the encoder magnet 67 is fixed thereto. The second sliding surface 119 has the same diameter as the first sliding surface 113, and the lip portion of the second seal member S2 abuts thereon. Also, the outer diameter of the second sliding surface 119 is smaller than the outer diameter of the load side end portion of the input shaft 21. In this case, since the second sliding surface 119 is not provided on the input shaft 21, losses can be reduced.

[0020] The second casing 72 has a hollow flange shape that closes the anti-input side of the stator core 13 and has a hollow portion through which the motor shaft 11 passes at the center. The first motor bearing 15 and the first seal member S1 are disposed between the hollow portion of the second casing 72 and the motor shaft 11. The first seal member S1 is disposed on the anti-input side of the motor bearing 15. The third casing 73 has a cylindrical shape surrounding the stator core 13. The fourth casing 74 is a flange-shaped member that closes the input side of the stator core 13 and has a hollow portion through which the motor shaft 11 passes at the center. The second motor bearing 16 is disposed between the hollow portion of the fourth casing 74 and the motor shaft 11.

[0021] The stator core 13 is fixed to the inner periphery of the third casing 73 and faces the outer peripheral surface of the magnet 12 in the radial direction through a magnetic gap. The armature coil 14 is wound around the slots of the stator core 13. The magnet 12 is fixed to the magnet support portion 115 of the motor shaft 11, and magnetic poles are provided on the outer peripheral surface. The motor 1 outputs a rotational driving force to the motor shaft 11 based on a known principle by being supplied with driving power from a driving device (not shown), and drives the input shaft 21 to rotate.

[0022] (Reducer) The speed reducer 2 will be described. The speed reducer 2 is not limited as long as it can decelerate and output the input rotation, and various speed reduction mechanisms can be used. The speed reducer 2 in the embodiment is an eccentric swing type speed reducer that causes one of the internal gear and the external gear to rotate by swinging the external gear that meshes with the internal gear, and outputs the generated rotation component from the output member to the driven member. The speed reducer 2 in the embodiment is a center crank type in which the rotation center line of the input shaft 21 is provided on the same axis as the central axis La.

[0023] The speed reducer 2 mainly includes an input shaft 21, external gears 33 and 34, an internal gear 43, carriers 35 and 36, a first casing 71, an inner pin 47, eccentric bearings 41 and 42, main bearings 37 and 38, and input shaft bearings 39 and 40. In particular, the input shaft 21, the external gears 33 and 34, the internal gear 43, the carriers 35 and 36, the inner pin 47, the eccentric bearings 41 and 42, the main bearings 37 and 38, and the input shaft bearings 39 and 40 constitute the speed reduction unit 3. The first casing 71 has a cylindrical shape surrounding the speed reduction unit 3, and the internal gear 43 is provided on the inner peripheral surface.

[0024] (Input shaft) The input shaft 21 is rotated around the rotation center line by the rotational power input from the motor 1. The input shaft 21 is a hollow shaft having a hollow hole​​​​​​​The input side of the input shaft 21 is supported by the second carrier 36 via the second input shaft bearing 40. The non-input side of the input shaft 21 is supported by the first carrier 35 via the input shaft bearing 39. In other words, the input shaft 21 is rotatably supported by the first carrier 35 and the second carrier 36. Various known bearing mechanisms can be employed for the input shaft bearings 39 and 40. In this example, the first input shaft bearing 39 is a ball bearing with spherical rolling elements, and the second input shaft bearing 40 is a roller bearing with cylindrical rolling elements.

[0027] The input shaft 21 has a connecting portion 212 in the portion of the hollow hole 211 corresponding to the third shaft portion 28 on the input side, for connection to the motor shaft 11. For example, the connecting portion 212 has a spline groove G21, and the spline groove G21 fits into the spline groove G11 of the connecting portion 112 of the motor shaft 11, thereby forming a spline connection. With this configuration, the hollow hole 111 and the hollow hole 211 communicate with each other.

[0028] (External gear) The external gears 33 and 34 are individually provided, corresponding to each of the multiple eccentric portions 25 and 26. The external gears 33 and 34 are pivotably mounted on the outer circumference of the eccentric portions 25 and 26 via eccentric bearings 41 and 42. In this example, the eccentric bearings 41 and 42 are roller bearings. The external gears 33 and 34 mesh internally with the internal gear 43 while each pivoting. Corrugated teeth are formed on the outer circumference of the external gears 33 and 34, and as these teeth move while in contact with the internal gear 43, the external gears 33 and 34 can pivot in a plane normalized to the central axis.

[0029] (Internal gear) The internal gear 43 meshes with the external gears 33 and 34. The internal gear 43 in this embodiment has a plurality of external pins 44 arranged in pin grooves formed at predetermined intervals in the circumferential direction on the inner surface of the first casing 71. The external pins 44 are cylindrical pin members that are rotatably supported in the pin grooves of the first casing 71. The external pins 44 constitute the internal teeth of the internal gear 43. The number of external pins 44 (number of internal teeth) of the internal gear 43 is slightly greater (only 1 in this example) than the number of external teeth of the external gears 33 and 34.

[0030] (Internal pin) Multiple internal pin holes 45 and 46 are formed in the external gears 33 and 34 at positions offset from their axes. An internal pin 47 passes through the internal pin holes 45 and 46. A cylindrical sleeve 48 is positioned around the outer circumference of the internal pin 47. The sleeve 48 functions as a sliding accelerator to facilitate smooth sliding with the internal pin holes 45 and 46. The outer diameter of the sleeve 48 is smaller than the inner diameter of the internal pin holes 45 and 46 by an amount equivalent to twice the eccentricity. A gap is provided between the sleeve 48 and the internal pin 47 to absorb the oscillation component of the external gears 33 and 34, and the internal pin 47 is always in contact with a portion of the internal pin holes 45 and 46 via the sleeve 48. The internal pin 47 revolves around the axis of the input shaft 21 in synchronization with the rotation component of the external gears 33 and 34, causing the carriers 35 and 36 to rotate around the axis of the input shaft 21. The internal pin 47 constitutes a pin-shaped member that contributes to the transmission of power between the carriers 35 and 36 and the external gears 33 and 34.

[0031] (Carrier) The carriers 35 and 36 have a circular shape overall. The first carrier 35 is positioned on the side of the external gears 33 and 34 that is not the input side, and the second carrier 36 is positioned on the side of the external gears 33 and 34 that is the input side. The first carrier 35 is rotatably supported by the first casing 71 via the first main bearing 37. The second carrier 36 is rotatably supported by the first casing 71 via the second main bearing 38. The first carrier 35 rotatably supports the side of the input shaft 21 that is not the input side via the first input shaft bearing 39. The second carrier 36 rotatably supports the input side of the input shaft 21 via the second input shaft bearing 40. Various known bearing mechanisms can be employed for the main bearings 37 and 38, and in this example, the main bearings 37 and 38 are angular contact roller bearings. The inner rolling surfaces of the main bearings 37 and 38 are formed on the carriers 35 and 36.

[0032] The internal pin 47 is integrally formed with the first carrier 35 and extends axially from the input side of the first carrier 35 toward the second carrier 36. The carriers 35 and 36 are connected to each other by screwing a bolt B8 through a through hole in the second carrier 36 into a tapped hole at the end of the internal pin 47.

[0033] The first carrier 35 functions as an output member that outputs rotational power to the driven member 81. The first casing 71 functions as a fixed member that is fixed to an external member 86 for supporting the gear motor 100. As an example, the driven member 81 and the first carrier 35 are connected to each other by screwing a bolt B1 through a through hole provided in the driven member 81 into a tapped hole provided in the non-input end of the first carrier 35.

[0034] The operation of the reduction gear 2 will now be explained. When rotational power is transmitted from the motor 1 to the input shaft 21, the eccentric portions 25 and 26 of the input shaft 21 rotate around the rotational centerline passing through the input shaft 21, and the external gears 33 and 34 oscillate due to these eccentric portions 25 and 26. At this time, the external gears 33 and 34 oscillate so that their own axes rotate around the rotational centerline of the input shaft 21. As the external gears 33 and 34 oscillate, the meshing positions of the external gears 33 and 34 and the external pins 44 of the internal gear 43 shift sequentially. As a result, for each rotation of the input shaft 21, a rotation occurs in either the external gears 33 and 34 or the internal gear 43 by an amount equivalent to the difference between the number of teeth of the external gears 33 and 34 and the number of external pins 44 of the internal gear 43. In this embodiment, the external gears 33 and 34 rotate, and a reduced rotation is output from the first carrier 35. As the first carrier 35 rotates, the driven member 81 connected to the first carrier 35 is rotated.

[0035] The functional unit 6 is described below. The functional unit 6 is surrounded by the fifth casing 75 and the sixth casing 76, with its input side closed by the sixth casing 76. The fifth casing 75 has a cylindrical portion and a protruding portion that extends radially inward from the input side of the cylindrical portion. The sixth casing 76 has a hollow portion 77 through which the motor shaft 11 passes, and the overall shape is substantially flange-like.

[0036] In this example, the functional unit 6 includes a brake 60 that decelerates the rotation of the motor 1 and an encoder 65 that detects the rotation of the motor 1. The brake 60 includes a brake disc 63 that rotates integrally with the motor shaft 11 and movable plates 61 and 62 that sandwich the brake disc 63 in the axial direction, and can apply braking force to the motor shaft 11 through the frictional force between the movable plates 61 and 62 and the brake disc 63. The encoder 65 includes an encoder magnet 67 that rotates integrally with the motor shaft 11 and an encoder detection unit 66 that detects the magnetic poles of the encoder magnet 67, and outputs an FG signal with a number of pulses corresponding to the rotational speed of the motor shaft 11 from the encoder detection unit 66. The encoder detection unit 66 is fixed to the protruding portion of the fifth casing 75.

[0037] The cylindrical member 5 is a member for passing wiring and piping between the input side and the non-input side of the gear motor 100. In the example shown in Figure 1, the cylindrical member 5 is a hollow member having a hollow hole 53 and is provided radially inside the motor shaft 11 and the input shaft 21. The cylindrical member 5 has a cylindrical portion 51 with a hollow hole 53, a flange portion 52 extending radially outward from the input side end of the cylindrical portion 51, and a third sliding surface 54 provided on the outer circumference of the non-input side of the cylindrical portion 51. The flange portion 52 of the cylindrical member 5 is attached to the input side end face of the sixth casing 76 by a plurality of bolts B7.

[0038] The first sealing member S1 is positioned between the hollow portion of the second casing 72 and the motor shaft 11, and the lip portion L1 of the first sealing member S1 abuts against the first sliding surface 113. The second sealing member S2 is positioned between the hollow portion of the sixth casing 76 and the motor shaft 11, and the lip portion of the second sealing member S2 abuts against the second sliding surface 119.

[0039] The third sealing member S3 is positioned between the hollow hole 82 of the driven member 81 and the cylindrical member 5, and the lip portion L3 of the third sealing member S3 abuts against the third sliding surface 54. In this embodiment, since the third sealing member S3 seals the space between the radial gap space J4 and the space on the load side of the reduction gear 2, it is possible to seal the space of the reduction gear 3 with the third sealing member S3 positioned at a location with a smaller diameter than the input shaft 21, and as a result, losses can be reduced. The third sealing member S3 is positioned on the outer circumference of the cylindrical member 5 and the member connected separately to the cylindrical member 5.

[0040] The fourth sealing member S4 is positioned between the first casing 71 and the first carrier 35 to prevent leakage of lubricant from the first main bearing 37.

[0041] Next, the characteristic configuration of this disclosure will be described with reference to Figures 1 and 2. Figure 2 is a magnified view of the area around the connection between the motor shaft 11 and the input shaft 21. The reducer 2 is filled with lubricant to lubricate the reduction section 3. To reduce the amount of lubricant leaking from the reducer 2, a sealing member is provided between the space J of the reduction section 3 of the reducer 2 and the external space. Space J includes the space between the first carrier 35 and the second carrier 36, as well as the space J1 on the input side of the second carrier 36, the space J2 on the non-input side of the first main bearing 37, and the space J3 on the non-input side of the first input shaft bearing 39. As described above, a fourth sealing member S4 is positioned between the first casing 71 and the first carrier 35 to seal space J2.

[0042] To seal the space J1, it is conceivable to provide a sealing member between the input shaft 21 and the second carrier 36. In this case, since the outer diameter of the input side of the input shaft 21 is larger than the outer diameter of the load side of the motor shaft 11, the sliding loss between the sealing member and the outer diameter of the input shaft 21 will be large. The sliding loss of the sealing member is a loss for the gear motor 100, and if this loss is large, the efficiency of the motor will decrease.

[0043] Therefore, in this embodiment, a sliding surface 113 on which the first seal member S1 is positioned is provided on the load side of the motor shaft 11, and the outer diameter D11 of the sliding surface 113 is set to be smaller than the outer diameter D21 of the third shaft portion 28 of the input shaft 21 of the reduction gear 2. In other words, the outer diameter D11 of the first sliding surface 113 is smaller than the outer diameter D21 of the motor 1 side end of the input shaft 21. The outer diameter D11 of the first sliding surface 113 is smaller than the outer diameter of any part of the input shaft 21. Note that the outer diameter of the portion of the input shaft 21 where the retaining ring is provided refers to the outer diameter of the retaining ring, not the outer diameter of the retaining ring groove. The third shaft portion 28 is the portion of the input shaft 21 between the reduction gear 3 and the sliding surface 113. In this case, the sliding loss of the seal member is reduced in proportion to the smaller outer diameter, and the decrease in motor efficiency can be suppressed.

[0044] Furthermore, in the example shown in Figure 1, the space J4 on the outer circumference of the cylindrical member 5 and the space of the reduction gear 2 are in communication. Specifically, the space J4 on the outer circumference of the cylindrical member 5 is in communication with the space J3 on the non-input side of the first input shaft bearing 39. As a result, lubricant mist may enter the functional unit 6 and the motor 1 from the input side region of space J4 through space J4. Therefore, in this embodiment, a second seal member S2 is placed on the non-load side of the motor shaft 11 to prevent lubricant from entering the inside of the motor 1. In this case, the intrusion of lubricant can be reduced.

[0045] In other words, the motor shaft 11 and input shaft 21 have a cylindrical member 5 positioned within the hollow holes 111 and 211, and the radial gap space J4 between the inner circumference of the motor shaft 11 and input shaft 21 and the outer circumference of the cylindrical member 5 is in communication with the internal space J3 of the reduction gear 2 so that lubricant can flow through it. Therefore, the embodiment has a second sealing member S2 for sealing the radial gap space J4 and the internal space of the motor 1.

[0046] To seal space J3, it is conceivable to provide a sealing member between the first carrier 35 and the input shaft 21. In this case, since the outer diameter of the input shaft 21 on the non-input side is larger than the outer diameter of the cylindrical member 5, the sliding loss between the sealing member and the outer diameter of the input shaft 21 becomes large. Therefore, in this embodiment, the cylindrical member 5 is located radially inward between the motor shaft 11 and the input shaft 21, and the third sealing member S3 is arranged on the cylindrical member 5. In this case, the sliding loss can be reduced compared to the case where a sealing member is provided between the first carrier 35 and the input shaft 21. As an example, to seal space J3, the third sealing member S3 is arranged between the driven member 81 and the cylindrical member 5.

[0047] The features of the gear motor 100 configured as described above will now be explained. The gear motor 100 is a gear motor comprising a motor 1 having a motor shaft 11 provided with a hollow hole 111, and a reduction gear 2 having an input shaft 21 provided with another hollow hole 211, and has a first sliding surface 113 on the load side of the motor shaft 11 on which a first sealing member S1 is disposed. The outer diameter D11 of the first sliding surface 113 is smaller than the outer diameter D21 of the motor 1 side end of the input shaft 21.

[0048] In conventional structures where oil seals are placed at both ends of the input shaft, if a hollow hole is provided, the outer diameters of the motor shaft and input shaft must be increased to ensure rigidity, and increasing these outer diameters increases the losses of the gear motor. In contrast, with the gear motor 100 configured above, the first seal member S1 is placed on the load side of the motor shaft 11, which has a smaller diameter than the input shaft 21 of the reduction gear 2. As a result, the sliding loss can be reduced by the amount of the smaller outer diameter, thus reducing the losses of the gear motor due to the oil seals. As in the gear motor 100 of the embodiment, placing seal members S1 and S2 on the smaller diameter parts of the high-speed rotating input shaft 21 and motor shaft 11, and placing seal member S3 on the low-speed rotating center pipe (cylindrical member 5), results in smaller losses even if the number of oil seals increases.

[0049] The present invention has been described above based on embodiments. These embodiments are illustrative, and it will be understood by those skilled in the art that various modifications and changes are possible within the scope of the claims of the present invention, and that such modifications and changes are also within the scope of the claims of the present invention. Accordingly, the description and drawings herein should be treated as illustrative rather than limiting.

[0050] (modified version) The following describes modified examples. In the drawings and descriptions of the modified examples, components and parts that are the same as or equivalent to those in the embodiments are denoted by the same reference numerals. Descriptions that overlap with those in the embodiments will be omitted as appropriate, and the descriptions will focus on the configurations that differ from those in the embodiments.

[0051] In the above description, an example was shown in which the cylindrical member 5 is attached to the casing 7 of the gear motor 100 and the cylindrical member 5 is non-rotating, but the present invention is not limited to this. For example, the cylindrical member 5 may be oriented in the opposite direction and attached to the driven member 81 (on the mating machine side). In this case, the third sealing member S3 can be positioned between the hollow hole 211 of the input shaft 21 and the cylindrical member 5. In this configuration, the cylindrical member 5 rotates integrally with the driven member 81 at a low speed.

[0052] The above description shows an example in which the input shaft 21 is spline-connected to the motor shaft 11, but the present invention is not limited thereto. The input shaft and the motor shaft may be connected by various known coupling methods.

[0053] The above description shows an example in which the gear motor 100 includes a functional unit 6, but the present invention is not limited thereto. The functional unit 6 may include only one of the brake and / or an encoder, or it may include other functional units. The gear motor 100 may not have a functional unit 6.

[0054] The above description shows an example where the gearbox is an eccentric oscillation type gearbox, but the gearbox reduction mechanism of the present invention is not limited to this. For example, the gearbox can employ various reduction mechanisms such as parallel axis type, orthogonal type, or simple planetary type, and may also be a flexible mesh type gearbox (sometimes called a wave gearbox) having cylindrical external gears. The gearbox may also be a cup type or a top hat type flexible mesh type gearbox.

[0055] The above description shows an example in which two external gears 33 and 34 are provided, but the present invention is not limited to this. The reduction gear may be provided with one or three or more external gears.

[0056] Each of these modifications produces the same functions and effects as the embodiments.

[0057] Any combination of the embodiments and modifications described above is also useful as an embodiment of the present invention. The new embodiments resulting from these combinations possess the combined effects of both the respective embodiments and modifications. [Explanation of Symbols]

[0058] 1 Motor, 2 Reducer, 3 Reduction section, 5 Cylindrical member, 7 Casing, 11 Motor shaft, 21 Input shaft, 33 External gear, 43 Internal gear, 111 Hollow hole, 211 Hollow hole, S1 First seal member, S2 Second seal member, S3 Third seal member, 100 Gear motor.

Claims

1. A gear motor comprising a motor having a motor shaft with a hollow hole and a reduction gear having an input shaft with another hollow hole, The motor shaft has a first sliding surface on the load side where the first sealing member is positioned, The outer diameter of the first sliding surface is smaller than the outer diameter of the motor-side end of the input shaft. The motor shaft and the input shaft have cylindrical members disposed within the hollow holes, The radial gap space between the inner circumference of the motor shaft and the input shaft and the outer circumference of the cylindrical member is in communication with the internal space of the reduction gear so that lubricant can flow through it. A gear motor having a second sealing member for sealing the radial gap space and the internal space of the motor.

2. The reduction gear comprises a gear and an input bearing that supports the input shaft on the motor side of the gear. The gear motor according to claim 1, wherein the outer diameter of the first sliding surface is smaller than the outer diameter of the input shaft on the motor side than the input bearing.

3. The gear motor according to claim 1 or 2, wherein the outer diameter of the first sliding surface is smaller than the outer diameter of any part of the input shaft.

4. The motor shaft has a second sliding surface on which the second sealing member is arranged. The gear motor according to claim 1, wherein the outer diameter of the second sliding surface is smaller than the outer diameter of the load-side end of the input shaft.

5. The gear motor according to any one of claims 1 to 4, wherein the input shaft of the reduction gear is connected to the motor shaft.

6. The gear motor according to claim 1, further comprising a third sealing member that seals the space between the radial gap and the space on the load side of the reduction gear.

7. The gear motor according to claim 6, wherein the third sealing member is arranged on the outer circumference of the cylindrical member.

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