Speed reducer
Patent Information
- Application Number
- JP2024510856
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Filing Date
- 2024-01-29
- Publication Date
- 2025-01-14
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Conventional speed reducers, such as cycloid reducers, face challenges in achieving a compact and balanced size due to their radial and axial dimensions, with existing solutions either increasing radial size or axial length.
A reduction gear design featuring an input shaft with an eccentric part and a flange, an inner trochoid plate, a pin held between the eccentric and trochoid surfaces, and a holding member that restricts pin rotation, allowing the pin to serve as both input and output, integrated within a housing with aligned rotation axes, reducing external size and increasing rigidity.
The solution results in a compact, well-balanced reduction gear that reduces rotational speed effectively while minimizing external size and enhancing rigidity, with the pin's dual function and trochoid plate configuration optimizing size and performance.
Abstract
Description
reducer
[0001] The present invention relates to a reducer that reduces the rotational speed input to an input shaft and outputs the reduced speed from an output shaft.
[0002] Conventionally, cycloid reducers have been disclosed that are interposed between an electric motor and a wheel hub to reduce the rotational speed of the motor and transmit the reduced rotational speed to a wheel hub bearing (for example, Patent Document 1 and Patent Document 2).
[0003] Patent No. 5010484 WO2021 / 024312
[0004] However, the reducer of Patent Document 1 requires the outer pins, the curved plate, and the output pins that pass through holes formed in the curved plate as essential components, resulting in a problem of large radial size. In contrast, the reducer of Patent Document 2 reduces the radial size by arranging the outer pins in the axial direction as a crankshaft, but the axial arrangement of the outer pins tends to make the reducer long in the axial direction. For this reason, a reducer with a well-balanced configuration and reduced size is desired.
[0005] The present invention has been made in view of this, and provides a reducer that is well-balanced and has a reduced size.
[0006] In order to solve the above problems, the reducer disclosed herein comprises an input shaft provided with an eccentric portion, an output shaft having a flange portion in which a circular hole is formed on a circumferential orbit centered on the rotation axis, an hypotrochoid plate having a through hole and a wave-shaped curved surface formed on the inner side surface of the through hole and fixed so as to prevent rotation, a pin clamped between the inner side surface of the hypotrochoid plate and the outer side surface of the eccentric portion, and a retaining member that holds the pin by restricting its rotation, wherein one end of the pin abuts at least a portion against the inner side surface of the circular hole and is rotatably received within the circular hole, and rotation of the input shaft causes the pin, which is clamped between the eccentric portion and the hypotrochoid plate, to rotate around the eccentric portion, and as the pin rotates within the circular hole while abutting at least a portion, the rotational motion of the pin is converted into rotational motion around the rotation axis of the output shaft, thereby rotating the output shaft.
[0007] According to this aspect, the pins serve as both output and input pins. The external pins used in conventional cycloidal reducers are not provided, which allows for a smaller external size. This reduces the number of parts, enabling a smaller overall size.
[0008] In one embodiment, the input shaft and the output shaft are rotatably held in a housing with their rotational axes aligned, and the hypotrochoid plate is fixed to the housing. In this embodiment, the hypotrochoid, which is subjected to a load, is completely fixed to the housing. This allows for high rigidity while maintaining a small size.
[0009] The holding member is configured in the shape of a flat ring, with holes formed on a circumferential orbit centered on the central axis of the ring, and the pins are press-fitted into the holes. According to this aspect, the holding member restricts rotation and allows only orbital revolution by press-fitting and connecting the pins. The flat-shaped holding member exerts the function of restricting rotation, does not become long in the axial direction, and can be accommodated in a compact size.
[0010] According to one aspect, an eccentric portion collar rotatably supported on the eccentric portion is attached to the eccentric portion, a first pin collar is attached to the pin, the pin is sandwiched between the inner peripheral side surface of the hypotrochoid plate and the outer peripheral side surface of the eccentric portion via the eccentric portion collar and the first pin collar, and a second pin collar is interposed between the circular hole and the pin. According to this aspect, smooth contact between the surfaces can be achieved, reducing friction and increasing rigidity.
[0011] In one aspect, the number of the pins is n, and the hypotrochoid plate has a leaf shape with n+1 or more trochoids offset. According to this aspect, the reduction ratio can be set by the number n.
[0012] In one embodiment, a first counterweight is attached to the input shaft at a different axial position from the pin, the first counterweight being formed so that its center of gravity is eccentric, and the first counterweight is attached so that the eccentric direction of the center of gravity is 180 degrees out of phase with the protruding direction of the eccentric portion of the input shaft.
[0013] In one embodiment, the eccentric portion is a first eccentric portion, the input shaft has a second eccentric portion that is 180 degrees out of phase with the first eccentric portion, and a second counterweight is attached to the second eccentric portion. The counterweight allows the input shaft to rotate in a balanced manner while maintaining high rigidity of the pin, thereby improving the performance of the reducer.
[0014] As is clear from the above description, it is possible to provide a reducer that is well-balanced and has a reduced size.
[0015] 5 is a cross-sectional view of a reducer according to an embodiment of the present invention. FIG. 6 is an exploded perspective view of the reducer. Bearings are omitted. FIG. 7 is a cross-sectional view taken along line A-A in FIG. 1. FIG. 8 is a cross-sectional view taken along line B-B in FIG. 1. FIG. 9 is a cross-sectional view of a reducer according to a modified example. FIG. 10 is an exploded perspective view of a reducer according to a modified example. Bearings are omitted. FIG. 11 is a cross-sectional view taken along line CC in FIG. 5. FIG. 12 is a cross-sectional view taken along line D-D in FIG. 5.
[0016] Specific embodiments of the present invention will be described below with reference to the drawings. The embodiments are illustrative and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention. In addition, in the following description of the embodiments and modifications, the same components are designated by the same reference numerals, and duplicated descriptions will be omitted as appropriate.
[0017] (First embodiment) Fig. 1 is a cross-sectional view of a reducer W1 according to a first embodiment. Fig. 2 is an exploded perspective view of the reducer W1. In Fig. 2, bearings are omitted.
[0018] The reducer W1 is mounted on the wheel drive unit of the vehicle and is interposed between the motor M and the wheel hub H. The reducer W1 has an input shaft 1 and an output shaft 10, and the rotation of the input shaft 1 is reduced and output from the output shaft 10.
[0019] The input shaft 1 is inserted into the motor M, and is rotated when the motor M rotates. The output shaft 10 is connected to a wheel hub H to which a wheel (not shown) is coupled, and the rotation of the output shaft 10 is transmitted to the wheel through the wheel hub H. The rotation of the motor M is reduced in speed by a reducer W1 and transmitted to the wheel, causing the wheel to rotate. The input shaft 1 may be directly driven as a rotating shaft on the motor M side, or may be connected to a rotating shaft of the motor M and driven.
[0020] As shown in Figure 2, the reducer W1 includes an input shaft 1, a first counterweight 2, a connecting member 3, a first pin collar 4, an eccentric portion collar 5, a pin 6, an inner trochoid plate 7, a retaining member 8, a second counterweight 9, an output shaft 10, a housing main body 11, a housing cover 12, and a second pin collar 13.
[0021] The housing body 11 and the housing cover 12 are housing (enclosure) parts for holding and protecting the components of the reducer W1, and are formed in a hollow, approximately cylindrical shape with both upper and lower ends open. The housing body 11 and the housing cover 12 each have a reduced-diameter opening on one side, and flanges 11a and 12a are formed at the other opening as joints. The housing body 11 and the housing cover 12 are box-shaped with the flanges 11a and 12a facing each other. The components are held in the internal space of the housing body 11 and the housing cover 12. A portion of the input shaft 1 is inserted and held in the reduced-diameter opening of the housing cover 12. Furthermore, a portion of the output shaft 10 is inserted and held in the reduced-diameter opening of the housing body 11.
[0022] The input shaft 1 is formed in a generally cylindrical rod shape and is housed inside a housing body 11 and a housing cover 12, which are housings (casings). One end (the lower side in FIG. 1 ) of the input shaft 1 protrudes from a reduced diameter opening in the housing cover 12 and is inserted into and fixed to the motor M.
[0023] The input shaft 1 has a first eccentric portion 1 a that is eccentric with respect to the rotation axis of the input shaft 1 at a portion accommodated in the housing.
[0024] The input shaft 1 also has a second eccentric portion 1b that is positioned 180 degrees out of phase with the first eccentric portion 1a. A first counterweight 2 is press-fitted onto the input shaft 1 in a portion other than the first eccentric portion 1a and the second eccentric portion 1b. A second counterweight 9 is attached to the second eccentric portion 1b via a bearing BR4. The first counterweight 2 and the second counterweight 9 function as weights to balance the rotating input shaft 1.
[0025] The first counterweight 2 has a generally disk-shaped but asymmetrical outer shape, and is formed so that the center of gravity is located eccentrically rather than at the center of the generally disk shape, so that the load is tilted in one direction. The direction of this load is 180 degrees different from the protruding direction of the first eccentric portion 1a, and the first counterweight 2 is attached to the input shaft 1 without using a bearing. As a result, the first counterweight 2 is balanced mainly with the first eccentric portion 1a, as well as with the connecting member 3, first pin collar 4, eccentric portion collar 5, pin 6, and part of the second pin collar 13.
[0026] The first counterweight 2 is attached to the input shaft 1 in an axially different position from that of a pin 6, which will be described later.
[0027] The disk-shaped second counterweight 9 has a through-hole 9a formed on a central circular orbit through which the pin 6 passes. The pin 6 is inserted into this through-hole 9a, but the through-hole 9a has a large inner diameter so that the inserted pin 6 does not come into contact with the through-hole 9a. The second counterweight 9 and the pin 6 inserted in the through-hole 9a do not come into contact with each other even when they rotate. In this way, the first counterweight 2 and the second counterweight 9 are configured to function without interfering with the movement of the pin 6.
[0028] The hypotrochoid plate 7 has a generally disk-shaped exterior with a large through-hole 7a formed in the center. A wave-shaped curve is formed on the inner peripheral side surface 7b of the through-hole 7a. The hypotrochoid plate 7 has its outer edge sandwiched between flanges 11a, 12a formed at the joining openings of the housing main body 11 and the housing cover 12, respectively, and is fastened to the housing main body 11 and the housing cover 12 with fixing members (not shown). In this way, the hypotrochoid plate 7 is fixed to the housing main body 11 and the housing cover 12, which are the housings, and will not rotate or move due to pressing or frictional forces even if it interferes with other parts.
[0029] The eccentric portion collar 5 has a short cylindrical shape and is rotatably supported on the first eccentric portion 1a of the input shaft 1 via a bearing BR2. The collar is a tubular member with a cylindrical hole formed therein, and is a component that is inserted into a mounted member to smooth the rotation of the mounted member. In this embodiment, collars are mainly disposed in locations where rigidity is required to withstand shear loads, and the collars can also be replaced with bearings as appropriate.
[0030] The eccentric collar 5 is disposed in the through hole 7 a of the internal trochoid plate 7. The eccentric collar 5 receives an eccentric input from the input shaft 1.
[0031] The pin 6 is formed in a cylindrical rod shape and is a component that is driven by the input shaft 1 and outputs the driving force to the output shaft 10. In other words, the pin 6 serves as both an input pin and an output pin. The outer and inner pins that were essential in the prior art cycloidal reducers can now be replaced with just the pin 6, and the reducer W1 has a more compact outer shape than the prior art.
[0032] A cylindrical first collar 4 is inserted into the pin 6. The pin 6 is sandwiched and held between the eccentric collar 5 and the hypotrochoid plate 7 at the location where the first collar 4 is inserted. More specifically, the pin 6 is sandwiched and held between the inner peripheral surface 7b of the hypotrochoid plate 7 and the outer peripheral surface of the first eccentric portion 1a via the first collar 4 and the eccentric collar 5. In this embodiment, to reduce friction, the eccentric collar 5 is attached to the first eccentric portion 1a, and the first collar 4 is attached to the pin 6. However, the pin 6 may also be directly sandwiched between the inner peripheral surface 7b of the hypotrochoid plate 7 and the outer peripheral surface of the first eccentric portion 1a without the first collar 4 and the eccentric collar 5. The pins 6 are arranged at equal intervals on the same circumference.
[0033] The waveform surface of the hypotrochoid plate 7 of the reducer W1 is designed, for example, as follows: In a hypotrochoid curve formed by a moving circle rolling inside a fixed circle, if there are n pins 6 rolling on the hypotrochoid curve, the shape of the rolling surface of the pin consisting of a hypotrochoid curve with n+1 leaves is defined.
[0034] In this embodiment, seven pins 6 are used, and eight waveforms (trochoid offset lobes) are provided on the inner peripheral side surface 7b of the hypotrochoid plate 7. Based on a trochoid curve, the outer peripheral surfaces of the pins are appropriately offset so that a portion of the pins is always in contact.
[0035] When the eccentric portion collar 5 is placed at a predetermined position in the through hole 7a of the hypotrochoid plate 7, a gap large enough to insert a pin 6 fitted with a first pin collar 4 is formed between the inner peripheral side surface 7b of the hypotrochoid plate 7 and the outer peripheral side surface of the eccentric portion collar 5. By inserting multiple pins 6 into this gap, the multiple pins 6 are sandwiched between the inner peripheral side surface 7b of the hypotrochoid plate 7 and the outer peripheral side surface of the first eccentric portion 1a.
[0036] The holding member 8 is a ring-shaped flat member with a central hole 8a formed in the center. In addition to the central hole 8a, the holding member 8 also has through holes 8b formed on a circumferential orbit centered on the central axis of the central hole 8a. The through holes 8b are provided around the central hole 8a of the holding member 8 at equal intervals in the circumferential direction, the number of which corresponds to the number of pins 6 (seven in this embodiment), and the pins 6 are each press-fitted into the through holes 8b. The holding member 8 holds the pins 6 and is rotatably supported by the first eccentric portion 1a via a bearing BR3 attached to the central hole 8a.
[0037] The connecting member 3 has the same configuration as the holding member 8, and is a ring-shaped flat plate member with a central insertion hole 3a formed in the center as an insertion hole. Like the holding member 8, through holes 3b are formed on a circumferential orbit centered on the central axis of the ring-shaped connecting member 3. The through holes 3b are provided around the central insertion hole 3a of the connecting member 3 at equal intervals in the circumferential direction, the number of which corresponds to the number of pins, and the pins 6 are press-fitted into these through holes 3b. The arrangement of the through holes 3b in the connecting member 3 is configured to be the same as the arrangement of the through holes 8b in the holding member 8. Therefore, the connecting member 3 and the pins 6 press-fitted into the holding member 8 are held parallel to each other.
[0038] The connecting member 3 and the holding member 8 connect the pin 6 by press-fitting, thereby preventing the pin 6 from rotating on its axis in response to an eccentric input from the input shaft 1, and allowing only rotation (mainly revolution) around the input shaft 1. The connecting member 3 and the holding member 8 both have the role of connecting the pin 6 and restricting the rotation of the pin 6, and are configured identically. They are interchangeable, and there is no problem with using only one of them.
[0039] The central through-hole 3a of the connecting member 3 is an insertion hole for the input shaft 1, and the connecting member 3 is disposed on the first eccentric portion 1a with the input shaft 1 inserted through the central through-hole 3a. The central through-hole 3a has an inner diameter larger than the outer diameter of the first eccentric portion 1a, so that the connecting member 3 does not come into contact with the input shaft 1, including the first eccentric portion 1a, even when the input shaft 1 is inserted through the central through-hole 3a.
[0040] The connecting member 3 is disposed on the first eccentric portion 1a of the input shaft 1 so that the eccentric portion collar 5 and the hypotrochoid plate 7 are sandwiched between the connecting member 3 and the retaining member 8 in the axial direction. The retaining member 8 is rotatably supported on the first eccentric portion 1a via a bearing, but the connecting member 3 is not held by the first eccentric portion 1a. Instead, it connects and holds the cylindrical pin 6, thereby supporting the retaining member 8. The pin 6 is supported at two points in the axial direction by the retaining member 8 and the connecting member 3, and is stably disposed. As with the retaining member 8, a bearing may be attached to the central insertion hole 3a of the connecting member 3 so that the connecting member 3 is rotatably supported on the first eccentric portion 1a of the input shaft 1.
[0041] The output shaft 10 has a solid flange shape, including a generally cylindrical rod-shaped shaft portion 10c and a flange portion 10a formed at one end of the shaft portion 10c. The output shaft 10 is disposed with the flange portion 10a facing the input shaft 1, and the other end (the upper side in FIG. 1 ) of the input shaft 1 is connected via a bearing BR5 to an engagement hole provided in the center of the bottom surface of the flange portion 10a. This allows the input shaft 1 and the output shaft 10 to be connected with their rotational axes aligned and to rotate relative to each other. Hereinafter, the rotational axes of both shafts will be referred to as the central axis x.
[0042] The input shaft 1 and the output shaft 10 are housed in a housing body 11 and a housing cover 12, which are housings, with one end protruding from an opening, and are rotatably held within the housing body 11 and the housing cover 12 via bearings BR1 and BR6, respectively. An end of the shaft portion 10c of the output shaft 10 protrudes from the housing body 11 and is connected to the wheel hub H. The outer peripheral surface of the shaft portion 10c is fixed to the wheel hub H, and the rotation of the output shaft 10 is transmitted to rotate the wheel hub H.
[0043] The flange portion 10a of the output shaft 10 is provided with circular holes 10b, the number of which corresponds to the number of pins, spaced equally in the circumferential direction on a circular orbit centered on the central axis x. One end of the pin 6 (the upper end in FIG. 1 ) is received in the circular holes 10b so as to be eccentrically rotatable.
[0044] A cylindrical second collar 13 configured similarly to the first collar 4 is inserted into the upper end of the pin 6, and the pin 6 is received in the circular hole 10b at the upper end through which the second collar 13 is inserted, allowing eccentric rotation. The circular hole 10b is formed so that at least a portion of the outer circumferential side of one of the pins 6 always abuts against it, and at least a portion of the outer circumferential side of the pin 6 abuts against the inner circumferential side of the circular hole 10b via the second collar 13, so that the outer circumferential side of the second collar 13 presses against the inner circumferential side of the circular hole 10b while rotating. As a result, the orbital rotation of the pin 6 is converted into a movement that rotates the output shaft 10 about the central axis x.
[0045] The round hole 10b is formed so that its diameter is larger than the outer diameter of the pin 6 through which the second collar 13 is inserted. The second collar 13 has the pin 6 inserted therethrough, allowing the pin 6 and the second collar 13 to rotate relative to each other, and is arranged so that at least a portion of the outer peripheral side surface of the second collar 13 abuts against the round hole 10b. The rotation of the pin 6 is transmitted to the output shaft 10 via the second collar, causing the output shaft 10 to rotate about the central axis x.
[0046] (Movement of reducer W1) The operation of the reducer W1 will be described. Fig. 3 is a cross-sectional view taken along line A-A in Fig. 1. This is an explanatory diagram mainly showing the movement of the input shaft 1 and the pin 6. Fig. 4 is a cross-sectional view taken along line B-B in Fig. 1. This is an explanatory diagram mainly showing the movement of the output shaft 10 and the pin 6.
[0047] First, the movement of the input shaft 1 and pin 6 will be described with reference to Figure 3. When the motor M is driven and the input shaft 1 rotates around the central axis x, the eccentric portion collar 5 supported by the first eccentric portion 1a via the bearing BR2 receives an eccentric input from the input shaft 1 and rotates around the central axis x in the direction opposite to the rotational direction of the input shaft 1, while revolving in the same direction as the rotational direction of the input shaft 1.
[0048] When the input shaft 1 rotates, the offset load of the first counterweight 2, which acts as a balancer, keeps the movement of the center of gravity of the input shaft 1, which has the first eccentric portion 1a and the second eccentric portion 1b, within an allowable range, ensuring stable rotation of the input shaft 1. Furthermore, the second counterweight 9, which is rotatably supported on the second eccentric portion 1b, rotates 180 degrees out of phase with the first eccentric portion 1a, thereby achieving balance.
[0049] The pin 6 is sandwiched between the first eccentric portion 1a and the inner peripheral side surface 7b of the hypotrochoid plate 7 via the eccentric portion collar 5 and the first pin collar 4 within the through hole 7a of the hypotrochoid plate 7. The hypotrochoid plate 7 is completely fixed to the housing main body 11 and housing cover 12, which form the housing, and does not rotate or move. The pin 6 is connected by press-fitting to the connecting member 3 and the retaining member 8, and the rotation of each pin 6 is restricted. Therefore, the pin 6 is driven by the eccentric portion collar 5 via the first pin collar 4, and revolves around the first eccentric portion 1a while moving along the inner peripheral side surface 7b of the hypotrochoid plate 7.
[0050] Here, the wave-shaped surface of the inner peripheral side surface 7b is formed so that the number of trochoid offset lobes (n+1) is greater than the number of pins (n). The trochoid offset lobes formed with n+1 lobes means that the first eccentric portion 1a is configured to rotate once with n+1 pins. However, since there are only n pins in reality, the pins are relatively delayed in rotation by 1 / (n+1) rotations. This delay causes the pins to rotate in the opposite direction, slowing down the rotation. That is, when the input shaft 1 rotates once, the first eccentric portion 1a rotates once in the same rotational direction as the input shaft 1, and the pin 6 revolves 1 / 8 of a rotation in the opposite direction to the rotational direction of the input shaft 1. The rotation of the input shaft 1 is decelerated to 1 / 8 of the rotational speed of the input shaft 1, causing the pin 6 to revolve.
[0051] Next, the relationship between the pin 6 and the output shaft 10 will be shown with reference to FIG.
[0052] The pin 6 is inserted into the circular hole 10b of the output shaft 10, and the second collar 13 is disposed so as to abut against the inner surface of the circular hole 10b. The pin 6 moves along the inner surface of the circular hole 10b via the second collar 13, and revolves at a reduced speed in the direction opposite to the rotational direction of the input shaft 1. The rotation of the pin 6 is restricted, and the movement of the pin 6 relative to the circular hole 10b is accepted by the second collar 13 as rotation along the inner surface of the circular hole 10b. The reduced speed revolving motion of the pin 6 pushes against the inner surface of the circular hole 10b, causing the output shaft 10 to rotate about the central axis x.
[0053] With the above configuration, the rotation of the input shaft 1 is transmitted to the output shaft 10 as rotation in the opposite direction at a rotational speed of 1 / (n+1). The speed reducer W1 rotates the wheel connected to the wheel hub H at a rotational speed reduced by 1 / (n+1) from the rotational speed of the motor M. The wheel rotates in the opposite direction to the rotational direction of the motor M.
[0054] (Effects) Unlike conventional reducers, the reducer W1 does not have an outer pin. This allows for a smaller external size. Furthermore, the rotation of the pin 6 is restricted, and its eccentric movement and revolutionary rotation are absorbed by a round hole formed in the flange portion 10a of the output shaft 10. Only the revolutionary rotation of the pin 6 is transmitted to the output shaft 10, causing it to rotate. The reduction ratio of the reducer W1 is determined by the number of corrugations (the number of trochoid offset lobes) of the hypotrochoid plate 7 and the number of pins 6. Therefore, even if the reduction ratio is increased, the outer diameter does not increase. Since the pin 6 serves as both an output pin and an input pin and can be integrated, the number of parts is reduced, allowing for a smaller size. In this way, the reducer W1 is configured to be well-balanced and compact overall.
[0055] In addition, the inner trochoid plate 7, which is subject to a large load, is fixed to the housing, which increases rigidity. The collar also smooths the rotation of the pin and is resistant to radial loads. The trochoid curve is used, and contact with the outer surface of the pin 6 prevents collision noise and allows for smooth rotation. In this way, the reducer W1 has increased rigidity.
[0056] (Modification) The configuration of the present disclosure is not limited to the form of the reducer W1 described above.
[0057] The second pin collar 13 is not limited to a cylindrical shape, and may be, for example, an eccentric collar formed such that the central axis of the outer peripheral side surface is offset from the central axis of the inner peripheral side surface.
[0058] The second pin collar of the eccentric collar is designated as second pin collar 13A. Second pin collar 13A has a cylindrical outer shape and a through hole with a central axis offset from the central axis of the cylindrical shape. The outer diameter of the cylindrical shape is approximately slightly smaller than the outer diameter of circular hole 10b. The diameter of the through hole is slightly larger than the diameter of pin 6. Second pin collar 13A is disposed in circular hole 10b with pin 6 inserted through the through hole. At this time, the offset of the central axis of the eccentric shape described above is configured to accommodate eccentric rotation of first eccentric portion 1a. Round hole 10b, second pin collar 13A of the eccentric collar, and pin 6 are supported to be rotatable relative to one another. When pin 6 rotates around first eccentric portion 1a, the outer peripheral surface of second pin collar 13A presses against the inner peripheral surface of circular hole 10b while rotating around the central axis of pin 6, thereby rotating output shaft 10 around central axis x.
[0059] (Modification 2) A reduction gear W2, which is a modification of the present invention, will be described with reference to Figs. 5 to 8. Fig. 5 is a cross-sectional view of the reduction gear W2. Fig. 6 is an exploded perspective view of the reduction gear W2. Bearings are omitted from Fig. 6.
[0060] As shown in Figures 5 and 6, the reducer W2 has an input shaft 1', a connecting member 3, a first pin collar 4, an eccentric portion collar 5, a pin 6, an internal trochoid plate 7, an output shaft 10, a housing main body 11, and a housing cover 12.
[0061] The reducer W2 does not have the first counterweight 2 or the second counterweight 9, but instead has another pair of a first pin collar 4', an eccentric collar 5', a pin 6', and an internal trochoid plate 7'. These are collectively referred to as the counterweight unit CU. The original first pin collar 4, the eccentric collar 5, the pin 6, and the internal trochoid plate 7 are collectively referred to as the original unit OU.
[0062] The input shaft 1' has a first eccentric portion 1a, does not have a second eccentric portion 1b, and instead has another first eccentric portion 1a', but has the same configuration as the input shaft 1. The first eccentric portion 1a' has an eccentric direction that is 180 degrees different from that of the first eccentric portion 1a, and is provided axially in the opposite direction (downward in FIG. 5 ) from the direction in which the output shaft 10 is disposed relative to the first eccentric portion 1a.
[0063] The counterweight unit CU is arranged 180 degrees out of phase with the paired original unit OU, that is, rotated 180 degrees, at the position of the first eccentric portion 1a' in the axial direction.
[0064] The connecting member 3 is disposed between the original unit OU and the counterweight unit CU. Both the pin 6' and the pin 6 are press-fitted into holes formed in the connecting member 3 to connect them. At this time, the pin 6 is press-fitted and protrudes in the direction in which the output shaft 10 is disposed, and the pin 6' is press-fitted and protrudes in the opposite direction to the pin 6, thereby connecting them. In this embodiment, the pin 6 is press-fitted into the top surface of the connecting member 3 and protrudes upward, and the pin 6' is press-fitted into the bottom surface of the connecting member 3 and protrudes downward, so that the pins 6, 6', and the connecting member 3 are integrally connected.
[0065] In this embodiment, the holding member 8 is not used, and the connecting member 3 performs the function of the holding member 8, connecting the pins 6 to restrict rotation and hold them. The connecting member 3 has the same configuration as the holding member 8, and it can be said that the connecting member 3 in this embodiment is the holding member 8. It is also possible to use the holding member 8 and another pair of holding members 8' instead of the connecting member 3.
[0066] The outer edges of the hypotrochoid plates 7 and 7' are clamped between the flange portion 11a of the housing main body 11 and the flange portion 12a of the housing cover 12, with a spacer 20 sandwiched between them, and are fastened to the housing main body 11 and the housing cover 12 with fixing members (not shown). In this way, the hypotrochoid plates 7 and 7' are fixed to the housing main body 11 and the housing cover 12, which are the housings.
[0067] The spacer 20 is arranged to secure a space for the connecting member 3 that is arranged between the original unit OU and the counterweight unit CU. The spacer 20 is configured in a flat ring shape, and the inner diameter of the through hole formed in the center is configured to be large so as not to interfere with the holding member 8.
[0068] The movement of the reducer W2 will now be described. Figure 7 is a cross-sectional view taken along line CC in Figure 5, which mainly shows the original unit OU. Figure 8 is a cross-sectional view taken along line DD in Figure 5, which mainly shows the counterweight unit CU.
[0069] As shown in FIGS. 7 and 8, the original unit OU and the counterweight unit CU are arranged with a phase difference of 180 degrees.
[0070] When the input shaft 1' rotates around the central axis x, the eccentric collar 5 held by the first eccentric portion 1a via the bearing BR2 receives the eccentric input, rotates on its axis, and revolves around the central axis x. The pin 6 is driven by the eccentric collar 5 via the first pin collar 4, and revolves around the first eccentric portion 1a while moving along the inner peripheral side surface 7b of the hypotrochoid plate 7.
[0071] When the input shaft 1 rotates, the counterweight unit CU moves in the same manner as the original unit OU, but with a phase difference of 180 degrees. That is, when the input shaft 1' rotates around the central axis x, the eccentric collar 5', which is held by the first eccentric portion 1a' via the bearing BR2', receives the eccentric input, rotates on its axis, and revolves around the central axis x. The pin 6' is driven by the eccentric collar 5' via the first pin collar 4', and revolves around the first eccentric portion 1a' while moving along the inner peripheral side surface 7b of the hypotrochoid plate 7.
[0072] By driving the counterweight unit CU in the opposite phase to the original unit OU, balance is achieved, the movement of the center of gravity of the input shaft 1' is kept within an allowable range, and the input shaft 1 rotates stably.
[0073] The rotation of the pin 6 is received in a round hole 10b of the output shaft 10, causing the output shaft 10 to rotate about the central axis x. The cross section of the output shaft 10 of the reducer W2 is the same as that of the reducer W1, and a description thereof will be omitted.
[0074] The rotation of the pin 6' is not output to the output shaft 10 or other parts, but is simply driven as a counterweight for balancing.
[0075] The counterweight unit CU uses the same parts as the original unit OU and functions as a well-balanced counterweight. Furthermore, since the same parts can be used for the corresponding parts of each unit, manufacturing costs can be reduced. The paired parts, eccentric collar 5 and eccentric collar 5', pin 6 and pin 6', and first pin collar 4 and first pin collar 4', move point-symmetrically about the central axis x. Therefore, the counterweight unit CU is a high-performance balancer for the reducer, which moves in a complex manner, improving the performance of the reducer W2.
[0076] The above describes preferred embodiments of the present invention, but the above embodiments are merely examples of the present invention, and these can be combined based on the knowledge of those skilled in the art, and such forms are also included in the scope of the present invention.
[0077] DESCRIPTION OF SYMBOLS 1: Input shaft 1a: First eccentric portion (eccentric portion) 1b: Second eccentric portion 2: First counterweight 3: Connecting member 3b: Through hole 4: First pin collar 5: Eccentric portion collar 6: Pin 7: Inner trochoid plate 7a: Through hole 7b: Inner peripheral side surface 8: Retaining member 8b: Through hole 9: Second counterweight 10: Output shaft 10a: Flange portion 10b: Round hole 11: Housing main body (housing) 12: Housing cover (housing) 13: Second pin collar W1: Reducer W2: Reducer x: Central axis
Claims
1. an input shaft provided with an eccentric portion; an output shaft having a flange portion, the flange portion having a circular hole formed on a circumferential orbit about a rotation axis; a hypotrochoid plate having a through hole, a corrugated curved surface formed on an inner peripheral side surface of the through hole, and fixed so as not to rotate; a pin that is held between the inner peripheral side surface of the hypotrochoid plate and the outer peripheral side surface of the eccentric portion and is driven from the outer peripheral side surface of the eccentric portion; a holding member that holds the pin by restricting its rotation and is rotatable relative to the outer peripheral side surface of the eccentric portion that drives the pin; Equipped with One end of the pin is rotatably received in the circular hole with at least a portion of the pin abutting against an inner peripheral side surface of the circular hole, The rotation of the input shaft rotates the pin, which is sandwiched between the eccentric portion and the hypotrochoid plate, about the eccentric portion, The pin rotates in the circular hole while at least a portion of the pin abuts against the circular hole, and the rotational motion of the pin is converted into a rotational motion about the rotation axis of the output shaft, thereby rotating the output shaft. This reducer is characterized by the above.
2. The input shaft and the output shaft are rotatably held in a housing with their rotational axes aligned, The hypotrochoid plate is fixed to the housing. The reducer according to claim 1 .
3. The holding member is configured in a flat ring shape, and a hole is provided on a circumferential orbit centered on a central axis of the ring, and the pin is press-fitted into the hole. The reducer according to claim 1 or 2.
4. An eccentric portion collar is attached to the eccentric portion so as to be rotatably supported by the eccentric portion, and a first pin collar is attached to the pin, the pin is sandwiched between the inner peripheral side surface of the hypotrochoid plate and the outer peripheral side surface of the eccentric portion via the eccentric portion collar and the first pin collar, A second pin collar is interposed between the circular hole and the pin, The pin is driven by the eccentric collar, and the retaining member is rotatable relative to the eccentric collar. The reducer according to any one of claims 1 to 3.
5. The pins are provided in a number of n around the axis of the eccentric portion, and the hypotrochoid plate has a leaf shape obtained by offsetting n+1 or more trochoids. The reducer according to any one of claims 1 to 4.
6. A first counterweight is attached to the input shaft so that the center of gravity of the first counterweight is eccentric, and the first counterweight is attached to the input shaft at a position different from the pin in the axial direction. The first counterweight is attached such that an eccentric direction of the center of gravity is out of phase with a protruding direction of the eccentric portion of the input shaft by 180 degrees. The reducer according to any one of claims 1 to 5.
7. The eccentric portion is a first eccentric portion, the input shaft has a second eccentric portion that is 180 degrees out of phase with the first eccentric portion, A second counterweight is attached to the second eccentric portion. The reducer according to claim 6,
8. The eccentric portion is a first eccentric portion, The input shaft has an eccentric direction that is 180 degrees different from that of the first eccentric portion, and has another eccentric portion in the axial direction with respect to the first eccentric portion, The hypotrochoid plate and the pin are disposed as a unit on the other eccentric portion in the axial direction, out of phase with the unit by 180 degrees, and another pair of units are disposed on the other eccentric portion as a counterweight unit. The reducer according to any one of claims 1 to 5.