Speed reducer

Abstract

This speed reducer comprises: a rotary drive shaft of an actuator; a front-stage gear to which rotary drive force of the rotary drive shaft is transmitted; a rear-stage gear to which rotary drive force is transmitted from the front-stage gear; and an output shaft to which rotary drive force is transmitted from the rear-stage gear. A gear ratio between the front-stage gear and the rear-stage gear is set such that teeth of the front-stage gear to and on which a relatively large load torque is transmitted and acts when the output shaft rotates and the relatively large load torque is transmitted to and acts on teeth of the rear-stage gear are different from teeth of the front-stage gear to and on which a relatively large load torque is transmitted and acts when the relatively large load torque is transmitted to and acts on the rear-stage gear next time.

Description

Reducer

[0001] The present disclosure relates to a reducer.

[0002] Conventionally, Patent Document 1 describes a reducer (an actuator in Patent Document 1) that transmits the rotational driving force of a motor to an output shaft (an output shaft in Patent Document 1) by reducing the rotation of the rotational driving shaft of the motor (the motor shaft in Patent Document 1) by a reduction unit. The reduction unit is configured by meshing a plurality of gears. Specifically, it is composed of a pinion gear, a first intermediate gear, a second intermediate gear, and an output gear in this order from the rotational driving shaft of the motor toward the output shaft, and thereby the rotational driving force is transmitted to the output shaft.

[0003] The reducer described in Patent Document 1 reduces the rotational speed of the rotational driving shaft of the motor in the reduction unit, thereby reducing the rotational speed of the output shaft and generating a large torque. Due to this large torque, even when a large load torque that cannot be rotated by the motor alone acts from the outside, the output shaft can be rotated against it.

[0004] Japanese Patent Application Laid-Open No. 2021-134802

[0005] When a large load torque acts on the output shaft from the outside, a large force also acts on each tooth of the plurality of gears in the reduction unit that are meshing at that time. If the reducer is configured such that a relatively large load torque acts multiple times from the outside while the output shaft rotates by a predetermined angle of one rotation or less, each time a relatively large load torque acts, a large force acts on each tooth of the plurality of gears in the reduction unit that are meshing at that time. If the reducer is configured such that specific teeth of the plurality of gears in the reduction unit mesh with each other every time a relatively large load torque acts on the output shaft, a large force will repeatedly act only on the specific teeth, and in the worst case, the teeth may be damaged or broken. To prevent this, it is necessary to use a high-strength material to increase the strength of the gears. However, since high-strength materials are generally expensive, increasing the strength of the gears leads to an increase in the cost of the reducer, and there is room for improvement.

[0006] Therefore, in a gearbox configured such that a relatively large load torque is applied multiple times while the output shaft rotates by a predetermined angle of less than one revolution, there is a need for a gearbox in which the gear ratio is configured such that the load torque does not act on a specific tooth of the gear each time the relatively large load torque is transmitted.

[0007] One embodiment of the reduction gear according to the present disclosure comprises an actuator having a rotary drive shaft and outputting a rotational driving force from the rotary drive shaft; a front gear having a plurality of front teeth to which the rotational driving force is transmitted; a rear gear having a plurality of rear teeth to which the rotational driving force, reduced in speed from the rotational driving force transmitted to the front gear is transmitted; and an output shaft to which the rotational driving force transmitted to the rear gear is transmitted. The gear ratio between the front gear and the rear gear is set such that for a rotation of the output shaft of a predetermined angle of one revolution or less, a relatively large load torque acts on the output shaft multiple times, and the front tooth that was subjected to the relatively large load torque when the output shaft rotates and the relatively large load torque is transmitted to and acts on the rear teeth is different from the front tooth that was subjected to the other relatively large load torque when another relatively large load torque is transmitted to and acts on the rear teeth next.

[0008] In the gearbox of this embodiment, the gear ratio between the front gear and the rear gear is set so that a relatively large load torque is transmitted to a specific front tooth twice in a row. Therefore, when a relatively large load torque is transmitted to the rear tooth twice in a row, a relatively large force based on that load torque is not transmitted to the specific front tooth twice in a row. As a result, even if a relatively large load torque is repeatedly transmitted to the rear tooth, the repeated transmission of a relatively large force to the specific front tooth is avoided, and the occurrence of tooth chipping or breakage can be suppressed. This eliminates the need to make the front and rear gears high-strength using expensive materials, thus suppressing the cost increase of the gearbox.

[0009] This is a perspective view of a manifold having a reduction gear according to this embodiment. This is a cross-sectional view showing the state in which the flow path is switched by rotating the valve body of the first rotary valve. This is a graph showing the change in load torque when the output shaft is rotated. This is a diagram showing the meshing state of each gear when a relatively large load torque is first applied to the output shaft. This is a diagram showing the meshing state of each gear when a relatively large load torque is applied to the output shaft a second time. These are enlarged partial views of the first gear and the second gear.

[0010] The embodiments of the speed reducer according to this disclosure will be described in detail below with reference to the drawings. The embodiments described below are illustrative examples for explaining the speed reducer according to this disclosure, and the speed reducer is not limited to the embodiments described below. Therefore, the speed reducer according to this disclosure can be implemented in various forms without departing from its essence.

[0011] [Manifold Configuration] Figure 1 shows the configuration of a manifold 1 including a reduction gear 10 according to this embodiment. The manifold 1 comprises a first rotary valve 2, a second rotary valve 3, a first water pump 4, a second water pump 5, and a manifold body 6 having a plurality of flow paths 6a (see Figure 2) for circulating coolant through these. The manifold body 6 is formed by joining a plurality of resin housings by adhesive or other methods. Since the first rotary valve 2 and the second rotary valve 3 have similar configurations, only the first rotary valve 2 will be described below, and the description of the second rotary valve 3 will be omitted. The coolant is cooling water such as long-life coolant (LLC), or insulating oil such as paraffin.

[0012] The first rotary valve 2 comprises a reduction gear 10, a valve body 2a, a sealing material 2b, and a valve chamber 2c. The reduction gear 10 is fixed to the manifold body 6, exposed to the surface of the manifold body 6. The valve body 2a and the sealing material 2b, which is positioned radially outward from the valve body 2a, are both housed in the valve chamber 2c formed in the manifold body 6. The outer circumferential surface of the valve body 2a slides and rotates while in contact with the sealing portions 2b2 formed around the inner circumferential surfaces of each of the multiple flow ports 2b1 formed in the sealing material 2b through holes through which the coolant flows (see Figure 2). The sealing material 2b is made of an elastic material such as rubber.

[0013] In the first rotary valve 2 of this embodiment, the valve body 2a and sealing material 2b are housed in the valve chamber 2c, and the reduction gear 10 is fixed to the manifold body 6 to form a cover over the valve chamber 2c. At this time, one end of the valve body shaft 2d of the valve body 2a is connected to the output shaft 16 of the reduction gear 10 (see Figure 4), and the other end is supported by a shaft support hole (not shown) formed in the bottom surface of the valve chamber 2c. As the output shaft 16 of the reduction gear 10 rotates, the valve body shaft 2d rotates together with it, and as a result the valve body 2a rotates.

[0014] As shown in Figure 2, the first rotary valve 2 allows the coolant flowing through the flow path 6a formed inside the manifold body 6 to pass through the flow port 2b1 of the seal material 2b, through the flow path inside the valve body 2a, and out through another flow port 2b1 to the other flow path 6a. The first rotary valve 2 can switch the flow path 6a of the coolant flowing inside the manifold body 6 by rotating the output shaft 16 of the reduction gear 10 to rotate the valve body 2a (counterclockwise in Figure 2).

[0015] As described above, the outer circumferential surface of the valve body 2a of the first rotary valve 2 slides and rotates while in contact with the tip (the innermost diameter portion) of the seal portion 2b2 formed on the inner circumferential surface of the seal material 2b. The seal portion 2b2 is provided to suppress leakage of cooling water, and the valve body 2a rotates while its outer circumferential surface elastically deforms the tip of the seal portion 2b2. Therefore, the rotation of the valve body 2a constantly applies a load torque (sliding resistance between the valve body 2a and the seal portion 2b2 of the seal material 2b) to the output shaft 16 of the reduction gear 10.

[0016] The load torque acting on the output shaft 16 becomes relatively larger when the valve body 2a rotates and comes into contact with a new seal portion 2b2, riding up onto its tip and causing elastic deformation, and becomes relatively smaller after it has ridden onto the seal portion 2b2. In other words, the load torque acting on the output shaft 16 is not constant but changes depending on the angle of rotation of the output shaft 16 (see Figure 3). In this embodiment, the valve body 2a of the first rotary valve 2 rotates by a maximum of 135 degrees (an example of a predetermined angle), which is less than one rotation in both the clockwise and counterclockwise directions. That is, the output shaft 16 also rotates by a maximum of 135 degrees, and for each of those 135 degrees of rotation, a relatively large load torque acts multiple times (four times for every 45 degrees of rotation in this embodiment). Note that the states in Figure 2 (1) to (4) correspond to the states in Figure 3 (1) to (4), respectively.

[0017] [Configuration of the speed reducer] Next, the configuration of the speed reducer 10 will be described. As shown in Figure 4, the speed reducer 10 is composed of a motor 12 (an example of an actuator), a first stage gear 21 (an example of a preceding gear and a first gear), a first intermediate gear 31 (an example of a preceding gear, an intermediate gear, and a subsequent gear), a second intermediate gear 41 (an example of a preceding gear, an intermediate gear, and a subsequent gear), a third intermediate gear 51 (an example of a preceding gear, an intermediate gear, and a subsequent gear), a final stage gear 61 (an example of a subsequent gear), and an output shaft 16. The speed reducer 10 reduces and transmits the rotational driving force of the motor 12 in the order of the first stage gear 21, the first intermediate gear 31, the second intermediate gear 41, the third intermediate gear 51, and the final stage gear 61. The final stage gear 61 is mounted on the output shaft 16 so as to rotate integrally with it. The output shaft 16 outputs the rotational driving force transmitted from the motor 12 after being reduced in speed, thereby rotating the valve body 2a. It should be noted that "transmission of rotational driving force" is not limited to the transmission of rotational driving force between two meshing gears, but also includes the transmission of rotational driving force between two gears arranged via one or more meshing gears (i.e., not directly meshing). Furthermore, the transmission of rotational driving force from the rotational drive shaft 14 to the first-stage gear 21 attached to the rotational drive shaft 14 (described later), and the transmission of rotational driving force from the output shaft 16 to the final-stage gear 61 attached to the output shaft 16 are also included in "transmission of rotational driving force."

[0018] In the actual reduction gear 10, as shown in Figure 4, the motor 12, first stage gear 21, first intermediate gear 31, second intermediate gear 41, third intermediate gear 51, and final stage gear 61 are arranged so that they overlap each other and reduce the area when viewed in a direction parallel to the output shaft 16. However, for the sake of explanation, in Figure 4, the first stage gear 21, first intermediate gear 31, second intermediate gear 41, third intermediate gear 51, and final stage gear 61 are arranged in a straight line. The arrows shown in Figure 4 indicate the rotation direction of each gear.

[0019] The motor 12 has a rotary drive shaft 14 that outputs rotational driving force. The first stage gear 21 is attached to the rotary drive shaft 14 and rotates integrally with the rotary drive shaft 14. The first stage gear 21 is a spur gear and has a plurality of first stage teeth 21a (an example of a preceding tooth and a first tooth).

[0020] The first intermediate gear 31 is a two-stage gear in which two spur gears, a first large-diameter gear 33 (an example of an intermediate gear, a subsequent gear, and a second gear) and a first small-diameter gear 35 (an example of a preceding gear, an intermediate gear, and a first gear), are integrated so as to be coaxial. The first large-diameter gear 33 has a plurality of first large-diameter teeth 33a (an example of intermediate teeth, subsequent teeth, and a second tooth), and the first small-diameter gear 35 has a plurality of first small-diameter teeth 35a (an example of a preceding tooth, an intermediate tooth, and a first tooth) with fewer teeth than the first large-diameter teeth 33a. The number of teeth of the first large-diameter teeth 33a is greater than the number of teeth of the first stage teeth 21a. In addition, the first large-diameter teeth 33a of the first large-diameter gear 33 mesh with the first stage teeth 21a of the first stage gear 21. As a result, the rotational driving force of the motor 12 is reduced and transmitted to the first intermediate gear 31.

[0021] The second intermediate gear 41 is a two-stage gear in which two spur gears, a second large-diameter gear 43 (an example of an intermediate gear, a subsequent gear, and a second gear) and a second small-diameter gear 45 (an example of a preceding gear, an intermediate gear, and a first gear), are integrated so as to be coaxial. The second large-diameter gear 43 has a plurality of second large-diameter teeth 43a (an example of intermediate teeth, subsequent teeth, and a second tooth), and the second small-diameter gear 45 has a plurality of second small-diameter teeth 45a (an example of a preceding tooth, an intermediate tooth, and a first tooth) with fewer teeth than the second large-diameter teeth 43a. The number of teeth of the second large-diameter teeth 43a is greater than the number of teeth of the first small-diameter teeth 35a. In addition, the second large-diameter teeth 43a of the second large-diameter gear 43 mesh with the first small-diameter teeth 35a of the first intermediate gear 31. As a result, the rotational driving force of the motor 12, which has been reduced by the first intermediate gear 31, is further reduced and transmitted to the second intermediate gear 41.

[0022] The third intermediate gear 51 is a two-stage gear in which two spur gears, a third large-diameter gear 53 (an example of an intermediate gear, a subsequent gear, and a second gear) and a third small-diameter gear 55 (an example of a preceding gear, an intermediate gear, and a first gear), are integrated so as to be coaxial. The third large-diameter gear 53 has multiple third large-diameter teeth 53a (an example of intermediate teeth, subsequent teeth, and a second tooth), and the third small-diameter gear 55 has multiple third small-diameter teeth 55a (an example of a preceding tooth, an intermediate tooth, and a first tooth) which are fewer in number than the third large-diameter teeth 53a. The number of teeth of the third large-diameter teeth 53a is greater than the number of teeth of the second small-diameter teeth 45a. In addition, the third large-diameter teeth 53a of the third large-diameter gear 53 mesh with the second small-diameter teeth 45a of the second intermediate gear 41. As a result, the rotational driving force of the motor 12, which has been reduced by the first intermediate gear 31 and the second intermediate gear 41, is further reduced and transmitted to the third intermediate gear 51.

[0023] The final stage gear 61 has multiple final stage teeth 61a (an example of a later stage tooth). The number of teeth of the final stage teeth 61a is greater than the number of teeth of the third small diameter teeth 55a. In addition, the final stage teeth 61a of the final stage gear 61 mesh with the third small diameter teeth 55a of the third intermediate gear 51. As a result, the rotational driving force of the motor 12, which has been reduced by the first intermediate gear 31, the second intermediate gear 41, and the third intermediate gear 51, is further reduced and transmitted to the final stage gear 61. The rotational driving force of the motor 12, which has been reduced and transmitted to the final stage gear 61, is transmitted to the output shaft 16, which rotates integrally with the final stage gear 61, and rotates the valve body 2a of the first rotary valve 2.

[0024] Thus, in the reduction gear 10, the rotational driving force of the motor 12 is transmitted in the order of the first stage gear 21, the first intermediate gear 31, the second intermediate gear 41, the third intermediate gear 51, and the final stage gear 61, and is finally transmitted to the output shaft 16. This rotational driving force is transmitted while being reduced through the teeth of each of the two meshing gears.

[0025] [Gear Ratio of the Reducer] As described above, when the valve body 2a of the first rotary valve 2 rotates, a load torque is always acting on the output shaft 16. The direction in which the load torque acts is opposite to the direction of rotation of each gear (opposite to the arrow in Figure 4). The force based on the load torque acting on the output shaft 16 is transmitted in the following order and acts simultaneously on the meshing final stage gear 61's final stage tooth 61a, the third small diameter tooth 55a of the third small diameter gear 55 of the third intermediate gear 51 and the third large diameter tooth 53a of the third large diameter gear 53, the second small diameter tooth 45a of the second small diameter gear 45 of the second intermediate gear 41 and the second large diameter tooth 43a of the second large diameter gear 43, the first small diameter tooth 35a of the first small diameter gear 35 of the first intermediate gear 31 and the first large diameter tooth 33a of the first large diameter gear 33, and the first stage tooth 21a of the first stage gear 21. In other words, when a relatively large load torque is acting on the output shaft 16, a force based on the load torque acts on all the teeth that are meshing at that time. The force acting on the teeth of each gear that are meshing when a relatively large load torque is acting on the output shaft 16 is greater than the force acting on the teeth of each gear that are meshing when a smaller load torque is acting.

[0026] In this embodiment, when the output shaft 16 rotates 135 degrees, a relatively large load torque is applied to the output shaft 16 four times, and a relatively large force is also applied to the teeth of each gear that are meshing with it four times. When this relatively large force is applied four times, if a relatively large force is applied to a specific tooth (the same tooth) of each meshing gear, the rotation of the valve body 2a of the first rotary valve 2 will be repeated, causing the relatively large force to be applied repeatedly to that specific tooth, and in the worst case, the tooth may be chipped or broken. To prevent this, it is necessary to increase the strength of the first stage gear 21, the first intermediate gear 31, the second intermediate gear 41, the third intermediate gear 51, and the final stage gear 61 using high-strength materials. However, since high-strength materials are generally expensive, increasing the strength of these gears may lead to an increase in the cost of the reduction gear 10.

[0027] Therefore, in the reduction gear 10 of this embodiment, the gear ratio between any two gears that mesh is set such that the teeth of each gear that are meshed when a relatively large load torque is applied to the output shaft 16 and thus act with a relatively large force are different from the teeth of each gear that are meshed when a relatively large load torque is applied to the output shaft 16 the next time (the second time) after the output shaft 16 (valve body 2a) has rotated and a relatively large load torque is applied to the output shaft 16.

[0028] Specific examples are shown in Figures 4 and 5. Figure 4 shows the meshing state of each gear when a relatively large load torque is first applied to the output shaft 16. Figure 5 shows the meshing state of each gear when the output shaft 16 is rotated 45 degrees clockwise from the state in Figure 4 and a relatively large load torque is applied to the output shaft 16 a second time. In Figure 4, the shaded teeth of each gear represent the teeth that were meshed when a relatively large load torque was first applied to the output shaft 16, resulting in a relatively large force being applied to them. In Figure 5, none of these shaded teeth are in a meshing position, indicating that a relatively large force based on the second relatively large load torque is not applied to these shaded teeth. In other words, the meshed teeth of each gear are all different when a relatively large load torque is first applied to the output shaft 16 and when a relatively large load torque is applied to the output shaft 16 a second time. In other words, the gear ratio is not such that when a relatively large load torque is applied twice to the output shaft 16 between any two meshing gears, a specific tooth will mesh twice in a row.

[0029] In this way, by setting the gear ratio between any two meshing gears so that a specific tooth does not mesh twice in a row, when a relatively large load torque is applied to the output shaft 16 multiple times, a relatively large force based on that relatively large load torque will not be applied to a specific tooth twice in a row, at least for two consecutive times. In other words, when a relatively large torque is applied to the output shaft 16 twice in a row, a specific tooth will not mesh twice in a row. Therefore, even if the valve body 2a of the first rotary valve 2 is rotated repeatedly, the repeated application of a relatively large force to a specific tooth is avoided, and the occurrence of tooth chipping or breakage can be suppressed. As a result, it is not necessary to make the gears high-strength using expensive materials, thus suppressing the cost increase of the reducer 10.

[0030] Next, we will explain how to determine the gear ratio such that, when a relatively large load torque is applied to the output shaft 16 twice in a row, no specific teeth mesh twice in a row between any two meshing gears.

[0031] Of the first stage gear 21, the first intermediate gear 31, the second intermediate gear 41, and the third intermediate gear 51, the gear closer to the motor 12 is designated as the first gear G1, and the gear further away from the motor 12 that meshes with the first gear G1 is designated as the second gear G2. If the number of teeth of the first gear G1 is Z1 and the number of teeth of the second gear G2 is Z2, then Z1 < Z2.

[0032] When a relatively large load torque is first applied to the output shaft 16, the final tooth 61a of the final stage gear 61 to which the force acts is defined as the meshing final stage tooth 61a1 (an example of a final stage tooth) (see Figure 4). Then, the tooth of the first gear G1 that directly or indirectly meshes with the meshing final stage tooth 61a1 when a relatively large load torque is first applied to the output shaft 16 is defined as the first gear tooth T1 (an example of a first tooth), and the tooth of the second gear G2 is defined as the second gear tooth T2 (an example of a second tooth). In the following explanation, as shown in Figure 4, the first small diameter gear 35 of the first intermediate gear 31 will be described as the first gear G1, and the second large diameter gear 43 of the second intermediate gear 41 will be described as the second gear G2. In this case, the first gear tooth T1 is one of the first small diameter teeth 35a, and the second gear tooth T2 is one of the second large diameter teeth 43a.

[0033] The rotation angle θ is defined as the angle of rotation from the first time a relatively large load torque is applied to the output shaft 16 until the next time a relatively large load torque is applied to the output shaft 16 (see Figure 5). The reduction ratio between the final stage gear 61 and the second gear G2 is defined as X.

[0034] From the above, when a relatively large load torque is first applied to the output shaft 16, the final stage tooth 61a1 of the final stage gear 61, the second gear tooth T2 of the second gear G2, and the first gear tooth T1 of the first gear G1 are meshing. These are all the shaded teeth shown in Figure 4. When the output shaft 16 rotates by a rotation angle θ from this state, a second relatively large load torque is applied to the output shaft 16. At this time, the final stage gear 61 also rotates by a rotation angle θ. Therefore, the second gear G2, which is directly or indirectly meshed with the final stage gear 61, rotates by an angle of X・θ, since the reduction ratio between it and the final stage gear 61 is X. Also, since the reduction ratio between the first gear G1 and the second gear G2 is Z2 / Z1, when the final stage gear 61 rotates by a rotation angle θ, the first gear G1 rotates by an angle of (Z2 / Z1)・X・θ.

[0035] When the angles of rotation of the first gear G1 and the second gear G2 at this time are converted to rotational speeds, the first gear G1 rotates at ((Z2 / Z1)・X・θ) / 360 and the second gear G2 rotates at (X・θ) / 360. The rotational speeds of the first gear G1 and the second gear G2 determine the positions of the first gear teeth T1 and the second gear teeth T2, but it is unknown whether the rotational speeds of the first gear G1 and the second gear G2 at this time are less than one rotation or one or more. For an integer number of rotations of one or more, the first gear teeth T1 and the second gear teeth T2 will still be in the meshing position, so it is necessary to convert the above rotational speeds to less than one rotation. Converting the rotational speed to less than one rotation is done by subtracting the integer part from the above rotational speeds.

[0036] Therefore, the rotational speeds of the first gear G1 and the second gear G2 are converted to less than one rotation using the Gaussian symbol. The Gaussian symbol is a symbol that represents the largest integer value that does not exceed a certain value. For example, if A is a real number and n is an integer, then if n ≤ A < n + 1 is satisfied, then [A] = n. Using this Gaussian symbol, the rotational speeds of the first gear G1 and the second gear G2 are converted to less than one rotation, resulting in the first gear G1 being ((Z2 / Z1)・X・θ) / 360 - [((Z2 / Z1)・X・θ) / 360] and the second gear G2 being (X・θ) / 360 - [(X・θ) / 360].

[0037] Here, as shown in Figure 6, in order for the first gear tooth T1 of the first gear G1 and the second gear tooth T2 of the second gear G2, which were directly or indirectly meshed with the final meshing tooth 61a1 of the final stage gear 61 when a relatively large load torque was first applied to the output shaft 16, to not mesh when a relatively large load torque is applied a second time, both the first gear tooth T1 and the second gear tooth T2 must have rotated more times than the number of rotations from the initial meshing position to the next tooth (hereinafter also referred to as 1 tooth) in both the clockwise and counterclockwise directions. For example, for the first gear G1, the number of teeth is Z1, so the number of rotations to 1 tooth is 1 / Z1. That is, if a force based on a relatively large load torque is applied a second time when the first gear tooth T1 has rotated more than 1 / Z1 from the initial meshing position, the first gear tooth T1 will not be in the meshing position (will not mesh). Similarly, in the second gear G2 with Z2 teeth, if a relatively large load torque is applied to the second gear tooth T2 at a position where it has rotated more than 1 / Z2 from the initial meshing position, the second gear tooth T2 will not be in the meshing position (will not mesh).

[0038] Expressed using the above formula, if the first gear G1 satisfies ((Z2 / Z1)・X・θ) / 360 - [((Z2 / Z1)・X・θ) / 360] > 1 / Z1 and 1 - (((Z2 / Z1)・X・θ) / 360 - [((Z2 / Z1)・X・θ) / 360]) > 1 / Z1, then when a relatively large load torque is applied for the second time, it will have rotated to a position where it has rotated more than one tooth in both the clockwise and counterclockwise directions, and the first gear tooth T1 is not in the meshing position.

[0039] Similarly, for the second gear G2, if (X・θ) / 360 - [(X・θ) / 360] > 1 / Z2 and 1 - ((X・θ) / 360 - [(X・θ) / 360]) > 1 / Z2 are satisfied, then when a relatively large load torque is applied for the second time, it will have rotated to a position where it has rotated more than one tooth in both the clockwise and counterclockwise directions, and the second gear tooth T2 will not be in the meshing position.

[0040] Even in the case of a two-stage gear system, such as the first intermediate gear 31, second intermediate gear 41, and third intermediate gear 51 of the reduction gear 10 in this embodiment, the above relationship is sufficient if it is maintained between the two meshing gears in each of the large-diameter gear and small-diameter gear.

[0041] [Other Embodiments] (1) In the above embodiment, three intermediate gears, a first intermediate gear 31, a second intermediate gear 41, and a third intermediate gear 51, are arranged between the first stage gear 21 and the final stage gear 61. However, the number of intermediate gears may be two or fewer, or four or more. Alternatively, the reduction gear 10 may have a configuration in which the first stage gear 21 and the final stage gear 61 are meshed together, without any intermediate gears. Any configuration of gears can be adopted for the reduction gear 10 as long as the rotational driving force of the motor 12 can be transmitted to the output shaft 16 with an appropriate reduction ratio.

[0042] (2) In the above embodiment, the gear ratio between any two meshing gears was set such that all teeth that were meshing when a relatively large load torque was first applied to the output shaft 16 would not mesh when a relatively large load torque was applied to the output shaft 16 a second time, in all the gears including the first stage gear 21, the first intermediate gear 31, the second intermediate gear 41, and the third intermediate gear 51. However, the embodiment is not limited to this. The gear ratio between any two meshing gears may be set such that at least one of all teeth that were meshing when a relatively large load torque was first applied to the output shaft 16 would not mesh when a relatively large load torque was applied to the output shaft 16 a second time.

[0043] (3) In the above-described embodiment and other embodiments (2), the action of the load torque on the two meshing gears has been described, but the present invention is not limited thereto. The gear ratio of any two gears (not directly meshing) arranged via one or more meshing gears may be configured to satisfy the action of the above load torque. For example, when a relatively large load torque first acts on the output shaft 16, the load torque is transmitted and acts on the teeth of the gear on the subsequent stage side among the teeth of each of the two arbitrary gears. When a relatively large load torque is transmitted and acts for the second time, the second relatively large load torque is transmitted and acts on teeth different from the teeth on which the relatively large load torque first acts on the gear on the preceding stage side. The gear ratio between the two arbitrary gears may be set in this manner.

[0044] (4) In the above-described embodiment, the output shaft 16 of the first rotary valve 2 of the manifold 1 was configured such that a relatively high load torque acts every 45 degrees, but an angle other than 45 degrees may also be used. Further, the angular intervals at which the relatively high load torque acts may not be equal intervals. Furthermore, if the rotation of the valve body 2a (output shaft 16) of the first rotary valve 2 at a predetermined angle is less than one rotation, it does not have to be 135 degrees. Depending on the shape of the valve body 2a of the first rotary valve 2 and the arrangement of the flow path 6a formed in the manifold body 6, it may be configured such that a relatively high load torque acts at an arbitrary angle and interval.

[0045] In the speed reducer 10 described in the above-described embodiment, the following configuration is recalled.

[0046] <1> One embodiment of the reduction gear (10) comprises an actuator (12) having a rotary drive shaft (14) and outputting rotational driving force from the rotary drive shaft (14), a front gear (21, 31, 35, 41, 45, 51, 55) having a plurality of front teeth (21a, 35a, 45a, 55a) to which rotational driving force is transmitted, a rear gear (31, 33, 41, 43, 51, 53, 61) having a plurality of rear teeth (33a, 43a, 53a, 61a) to which rotational driving force reduced from the rotational driving force transmitted to the front gear (21, 31, 35, 41, 45, 51, 55) is transmitted, and an output shaft (16) to which rotational driving force transmitted to the rear gear (31, 33, 41, 43, 51, 53, 61) is transmitted, wherein the output shaft (16) has a rotation of one revolution or less For rotations of a fixed angle, the output shaft (16) is subjected to multiple relatively large load torques, and the gear ratio between the front gears (21, 31, 35, 41, 45, 51, 55) and the rear gears (31, 33, 41, 43, 51, 53, 61) is set such that when the output shaft (16) rotates and a relatively large load torque is transmitted and acted upon the rear teeth (33a, 43a, 53a, 61a), the front teeth (21a, 35a, 45a, 55a) that are subjected to the relatively large load torque transmitted and acted upon are different from the front teeth (21a, 35a, 45a, 55a) that are subjected to the relatively large load torque transmitted and acted upon when other relatively large load torques are transmitted and acted upon the rear teeth (33a, 43a, 53a, 61a) that are subjected to the relatively large load torques transmitted and acted upon.

[0047] In the speed reducer (10) according to this aspect, the gear ratio between the front-stage gears (21, 31, 35, 41, 45, 51, 55) and the rear-stage gears (31, 33, 41, 43, 51, 53, 61) is set so that a relatively large load torque is not transmitted and applied to specific front-stage teeth (21a, 35a, 45a, 55a) continuously twice. Therefore, when a relatively large load torque is transmitted and applied to the rear-stage teeth (33a, 43a, 53a, 61a) continuously twice, a relatively large force based on the relatively large load torque is not transmitted and applied to the specific front-stage teeth (21a, 35a, 45a, 55a) continuously twice. Thus, even if the transmission and application of a relatively large load torque to the rear-stage teeth (33a, 43a, 53a, 61a) are repeated, the repeated transmission and application of a relatively large force to the specific front-stage teeth (21a, 35a, 45a, 55a) are avoided, and the occurrence of tooth loss, breakage, etc. can be suppressed. As a result, it is not necessary to make the front-stage gears (21, 31, 35, 41, 45, 51, 55) and the rear-stage gears (31, 33, 41, 43, 51, 53, 61) of high strength with expensive materials, so the cost increase of the speed reducer (10) is suppressed.

[0048] <2> In the speed reducer (10) described in <1> above, the front-stage gear having front-stage teeth is a first-stage gear (21) having first-stage teeth (21a) attached to the rotation drive shaft (14) and rotating integrally with the rotation drive shaft (14), and the rear-stage gear having rear-stage teeth is a final-stage gear (61) having final-stage teeth (61a) attached to the output shaft (16) and rotating integrally with the output shaft (16). It is preferable that the first-stage teeth (21a) of the first-stage gear (21) and the final-stage teeth (61a) of the final-stage gear (61) are meshed with each other.

[0049] In the speed reducer (10) according to this aspect, even if the transmission and application of a relatively large load torque from the output shaft (16) to the final-stage teeth (61a) are repeated between the first-stage teeth (21a) of the first-stage gear (21) and the final-stage teeth (61a) of the final-stage gear (61) that mesh with each other, the repeated transmission and application of a relatively large force to the specific first-stage teeth (21a) are avoided, and the occurrence of tooth loss, breakage, etc. can be suppressed.

[0050] <3> In the reduction gear (10) described in <1> above, a first stage gear (21) is attached to the rotary drive shaft (14) and rotates integrally with the rotary drive shaft (14) and has a plurality of first stage teeth (21a), a final stage gear (61) has a plurality of final stage teeth (61a) and to which the reduced rotational driving force is ultimately transmitted, an output shaft (16) is attached so as to rotate integrally with the final stage gear (61) and outputs the rotational driving force transmitted to the final stage gear (61), and a gear is positioned between the first stage gear (21) and the final stage gear (61) and reduces the rotational driving force of the first stage gear (21). The system comprises one or more intermediate gears (31, 33, 35, 41, 43, 45, 51, 53, 55) having multiple intermediate teeth (33a, 35a, 43a, 45a, 53a, 55a) that accelerate and ultimately transmit to the final stage gear (61), wherein the front stage gears (21, 31, 35, 41, 45, 51, 55) having front stage teeth (21a, 35a, 45a, 55a) are either a first stage gear (21) having first stage teeth (21a) or an intermediate gear (31, 35, 41, 45, 51, 55) having intermediate teeth (35a, 45a, 55a), and the rear stage teeth (33a, 43a, 53a, The subsequent gears (31, 33, 41, 43, 51, 53, 61) having 61a) are either intermediate gears (31, 33, 41, 43, 51, 53) having intermediate teeth (33a, 43a, 53a) or final gear (61) having final teeth (61a), and for rotations of the output shaft (16) of a predetermined angle of one revolution or less, a relatively large load torque is applied to the output shaft (16) multiple times, and when the output shaft (16) rotates and a relatively large load torque is applied to the output shaft (16), all intermediate teeth (33a, 3) that are subjected to the relatively large load torque are transmitted and act upon. It is preferable that the gear ratios between the first stage gear (21), one or more intermediate gears (31, 33, 35, 41, 43, 45, 51, 53, 55), and the final stage gear (61) are set such that at least one of the 5a, 43a, 45a, 53a, 55a) and the first stage teeth (21a) is different from the corresponding one of all the intermediate teeth (33a, 35a, 43a, 45a, 53a, 55a) and the first stage teeth (21a) that are affected when another relatively large load torque is subsequently applied to the output shaft (16).

[0051] In the reduction gear (10) according to this embodiment, the gear ratio between the first stage gear (21), one or more intermediate gears (31, 33, 35, 41, 43, 45, 51, 53, 55), and the final stage gear (61) is set such that at least one of the intermediate teeth (33a, 35a, 43a, 45a, 53a, 55a) and first stage teeth (21a) that are subjected to a relatively large load torque when another relatively large load torque is subsequently applied to the output shaft (16) is different from the corresponding one of the intermediate teeth (33a, 35a, 43a, 45a, 53a, 55a) and first stage teeth (21a) that are subjected to a relatively large load torque when another relatively large load torque is subsequently applied to the output shaft (16). Therefore, when a relatively large load torque is applied to the output shaft (16) twice in a row, at least one tooth will not be subjected to a relatively large force based on the relatively large load torque twice in a row. In other words, when a relatively large load torque is applied to the output shaft (16) twice in a row, at least one tooth will not be subjected to the relatively large load torque twice in a row. Therefore, even if the output shaft (16) rotates repeatedly, the repeated transmission and application of a relatively large force to at least one tooth is avoided, thereby suppressing the occurrence of chipping or breakage of that tooth.

[0052] <4> In the reduction gear (10) described in <3> above, it is preferable that the gear ratios between the first stage gear (21), one or more intermediate gears (31, 33, 35, 41, 43, 45, 51, 53, 55), and the final stage gear (61) are set such that when the output shaft (16) rotates and a relatively large load torque is applied to the output shaft (16), the gear ratios between each of the intermediate teeth (33a, 35a, 43a, 45a, 53a, 55a) and the first stage teeth (21a) that are subjected to a relatively large load torque are different from the gear ratios between the first stage gear (21), one or more intermediate gears (31, 33, 35, 41, 43, 45, 51, 53, 55), and the final stage gear (61), respectively, when another relatively large load torque is applied to the output shaft (16) next and a relatively large load torque is applied to the output shaft (16).

[0053] According to this embodiment, the gear ratios between the first stage gear (21), one or more intermediate gears (31, 33, 35, 41, 43, 45, 51, 53, 55), and the final stage gear (61) are set such that each of the intermediate teeth (33a, 35a, 43a, 45a, 53a, 55a) and the first stage tooth (21a) that are subjected to relatively large load torques when other relatively large load torques are then transmitted to and act upon the output shaft (16) are different from the corresponding each of the intermediate teeth (33a, 35a, 43a, 45a, 53a, 55a) and the first stage tooth (21a) that are subjected to other relatively large load torques when other relatively large load torques are then transmitted to and act upon the output shaft (16). This further suppresses the occurrence of tooth loss or breakage.

[0054] <5> In the reduction gear (10) described in <1> above, a first stage gear (21) is attached to the rotary drive shaft (14) and rotates integrally with the rotary drive shaft (14) and has a plurality of first stage teeth (21a), a final stage gear (61) has a plurality of final stage teeth (61a) and to which the reduced rotational driving force is ultimately transmitted, an output shaft (16) is attached so as to rotate integrally with the final stage gear (61) and outputs the rotational driving force transmitted to the final stage gear (61), and is positioned between the first stage gear (21) and the final stage gear (61) and reduces the rotational driving force of the first stage gear (21) to the final stage gear (61) The system includes one or more intermediate gears (31, 33, 35, 41, 43, 45, 51, 53, 55) having multiple intermediate teeth (33a, 35a, 43a, 45a, 53a, 55a) that transmit to the final stage gear (61), and the front stage gears (21, 31, 35, 41, 45, 51, 55) having front stage teeth (21a, 35a, 45a, 55a) are either a first stage gear (21) having first stage teeth (21a) or an intermediate gear (31, 35, 41, 45, 51, 55) having intermediate teeth (35a, 45a, 55a), and the rear stage gears (33a, 43a, 53a, 61a) having rear stage teeth ( 31, 33, 41, 43, 51, 53, 61) are either intermediate gears (31, 33, 41, 43, 51, 53) having intermediate teeth (33a, 43a, 53a) or final stage gears (61) having final stage teeth (61a), and for rotations of the output shaft (16) of a predetermined angle of one revolution or less, a relatively large load torque is applied to the output shaft (16) multiple times, and among the first stage gear (21) and the multiple intermediate gears (31, 33, 35, 41, 43, 45, 51, 53, 55), the first gear (21, 35, 45) has a first tooth (21a, 35a, 45a, 55a, T1) with a number of teeth Z1. In a first gear (21, 35, 45, 55, G1) and a second gear (33, 43, 53, G2) having a second tooth (33a, 43a, 53a, T2) with a number of teeth Z2, the reduction ratio between the final gear (61) and the second gear (33, 43, 53, G2) is X, and when the output shaft (16) rotates and a relatively large load torque acts on the output shaft (16), the first tooth (21a, 35a, 45a, 55a, G1) of the first gear (21, 35, 45, 55, G1) which is subjected to the relatively large load torque,At least one of the second teeth (33a, 43a, 53a, T2) of T1) and the second gear (33, 43, 53, G2) is such that when the output shaft (16) rotates by an angle θ and another relatively large load torque is applied to the output shaft (16), ((Z2 / Z1)・X・θ) / 360 - [((Z2 / Z1)・X・θ) / 360] > 1 / Z1 and 1 - (((Z2 / Z1)・X・θ) / 360 - [((Z2 / Z1)・X・θ) / 360]) > 1 / Z1 (where, It is preferable that the first gear (21, 35, 45, G1) rotates so as to satisfy (X・θ) / 360 - [(X・θ) / 360] > 1 / Z2 and the second gear (33, 43, 53, G2) rotates so as to satisfy 1 - ((X・θ) / 360 - [(X・θ) / 360]) > 1 / Z2 (where [ ] is the Gauss symbol).

[0055] In the reduction gear (10) according to this embodiment, the following are defined: a first stage gear (21) and a plurality of intermediate gears (31, 33, 35, 41, 43, 45, 51, 53, 55), a first gear (21, 35, 45, 55, G1) having first teeth (21a, 35a, 45a, 55a, T1) with a number of teeth Z1, and a second gear (33, 43, 53, G2) having second teeth (33a, 43a, 53a, T2) with a number of teeth Z2, to which the rotational driving force transmitted to the first gear (21, 35, 45, 55a, G1) is reduced and transmitted. Then, when a relatively large load torque is first applied to the output shaft (16), and the output shaft (16) rotates by a rotation angle θ, and another relatively large load torque is applied to the output shaft (16), at least one of the first gear (21, 35, 45, 55, G1) and the second gear (33, 43, 53, G2), which are subjected to the transmission of this relatively large load torque, rotates in a manner that satisfies the above equation. As a result, the teeth of the gears that satisfy the above equation among the first teeth (21a, 35a, 45a, 55a, T1) and the second teeth (33a, 43a, 53a, T2) are not subjected to two consecutive relatively large forces based on a relatively large load torque.

[0056] This disclosure is applicable to speed reducers.

[0057] 10: Reducer, 12: Motor (actuator), 14: Rotary drive shaft, 16: Output shaft, 21: First stage gear (front gear, first gear), 21a: First stage tooth (front tooth, first tooth), 31: First intermediate gear (front gear, intermediate gear, rear gear), 33: First large diameter gear (intermediate gear, rear gear, second gear), 33a: First large diameter tooth (intermediate tooth, rear tooth, second 45: Teeth), 35: First small diameter gear (front gear, intermediate gear, first gear), 35a: First small diameter tooth (front tooth, intermediate tooth, first tooth), 41: Second intermediate gear (front gear, intermediate gear, rear gear), 43: Second large diameter gear (intermediate gear, rear gear, second gear), 43a: Second large diameter tooth (intermediate tooth, rear tooth, second tooth), 45: Second small diameter gear (front gear, intermediate gear, first 1st gear), 45a: 2nd small diameter teeth (front teeth, intermediate teeth, 1st tooth), 51: 3rd intermediate gear (front gear, intermediate gear, rear gear), 53: 3rd large diameter gear (intermediate gear, rear gear, 2nd gear), 53a: 3rd large diameter teeth (intermediate teeth, rear teeth, 2nd tooth), 55: 3rd small diameter gear (front gear, intermediate gear, 1st gear), 55a: 3rd small diameter teeth (front teeth, intermediate teeth, 61: Final gear (rear gear), 61a: Final gear tooth (rear gear), 61a1: Meshing final gear tooth (final gear), G1: First gear, G2: Second gear, T1: First gear tooth (first tooth), T2: Second gear tooth (second tooth), X: Reduction ratio between the final gear and the second gear, Z1: Number of teeth on the first gear, Z2: Number of teeth on the second gear, θ: Rotation angle of the output shaft

Claims

1. A reduction gear comprising: an actuator having a rotary drive shaft and outputting a rotational driving force from the rotary drive shaft; a front gear having a plurality of front teeth and to which the rotational driving force is transmitted; a rear gear having a plurality of rear teeth and to which the rotational driving force, reduced in speed from the rotational driving force transmitted to the front gear, is transmitted; and an output shaft to which the rotational driving force transmitted to the rear gear is transmitted, wherein for a rotation of the output shaft by a predetermined angle of one revolution or less, a relatively large load torque acts on the output shaft multiple times, and the gear ratio between the front gear and the rear gear is set such that the front tooth that is acted upon when the output shaft rotates and the relatively large load torque is transmitted and acts on the rear teeth is different from the front tooth that is acted upon when another relatively large load torque is transmitted and acts on the rear teeth next.

2. The gear reducer according to claim 1, wherein the front gear having front teeth is a first gear having first teeth that is attached to the rotary drive shaft and rotates integrally with the rotary drive shaft, and the rear gear having rear teeth is a final gear having final teeth that is attached to the output shaft and rotates integrally with the output shaft, and the first teeth of the front gear and the final teeth of the final gear mesh with each other.

3. The device comprises: a first-stage gear mounted on the rotary drive shaft and rotating integrally with the rotary drive shaft, having a plurality of first-stage teeth; a final-stage gear having a plurality of final-stage teeth, to which the reduced rotational driving force is ultimately transmitted; an output shaft mounted so as to rotate integrally with the final-stage gear, and outputting the rotational driving force transmitted to the final-stage gear; and one or more intermediate gears positioned between the first-stage gear and the final-stage gear, having a plurality of intermediate teeth that reduce the rotational driving force of the first-stage gear and ultimately transmit it to the final-stage gear, wherein the preceding gear having the preceding teeth is either the first-stage gear having the first-stage teeth or the intermediate gear having the intermediate teeth; the subsequent gear having the subsequent teeth is either the intermediate gear having the intermediate teeth or the final-stage gear having the final-stage teeth; and for rotations of the output shaft of a predetermined angle of one revolution or less, the output shaft is subjected to the relatively large load torque multiple times. The gear ratio between the first stage gear, one or more intermediate gears, and the final stage gear is set such that when the output shaft rotates and the relatively large load torque acts on the output shaft, at least one of all the intermediate teeth and the first stage teeth that are affected by the relatively large load torque is transmitted to it is different from the corresponding one of all the intermediate teeth and the first stage teeth that are affected by the other relatively large load torque when another relatively large load torque acts on the output shaft next.

4. The gear ratio between the first stage gear, one or more intermediate gears, and the final stage gear is set such that when the output shaft rotates and the relatively large load torque acts on the output shaft, the gear ratio between each of the intermediate teeth and the first stage teeth that are affected by the relatively large load torque transmitted to them is different from the gear ratio between each of the corresponding intermediate teeth and the first stage teeth that are affected by the other relatively large load torque transmitted to them when another relatively large load torque acts on the output shaft next.

5. The device comprises: a first-stage gear mounted on the rotary drive shaft and rotating integrally with the rotary drive shaft, having a plurality of first-stage teeth; a final-stage gear having a plurality of final-stage teeth, to which the reduced rotational driving force is ultimately transmitted; an output shaft mounted so as to rotate integrally with the final-stage gear, and outputting the rotational driving force transmitted to the final-stage gear; and one or more intermediate gears positioned between the first-stage gear and the final-stage gear, having a plurality of intermediate teeth that reduce the rotational driving force of the first-stage gear and ultimately transmit it to the final-stage gear, wherein the preceding gear having the preceding teeth is either the first-stage gear having the first-stage teeth or the intermediate gear having the intermediate teeth; the subsequent gear having the subsequent teeth is either the intermediate gear having the intermediate teeth or the final-stage gear having the final-stage teeth; and for rotations of the output shaft of a predetermined angle of one revolution or less, the output shaft is subjected to the relatively large load torque multiple times. Among the first stage gear and the plurality of intermediate gears, a first gear having a first tooth with a number of teeth Z1, and a second gear having a second tooth with a number of teeth Z2 to which the rotational driving force transmitted to the first gear is reduced and transmitted, wherein the reduction ratio between the final stage gear and the second gear is X, and when the output shaft rotates and the relatively large load torque acts on the output shaft, at least one of the first tooth of the first gear and the second tooth of the second gear to which the relatively large load torque is transmitted and acts, when the output shaft then rotates by a rotation angle θ and another relatively large load torque acts on the output shaft, ((Z2 / Z1)・X・θ) / 360 - [((Z2 / Z1)・X・θ) / 360] > 1 / Z1 and The gearbox according to claim 1, wherein the first gear rotates such that 1 - (((Z2 / Z1)・X・θ) / 360 - [((Z2 / Z1)・X・θ) / 360]) > 1 / Z1 (where [ ] is the Gaussian symbol), and the second gear rotates such that (X・θ) / 360 - [(X・θ) / 360] > 1 / Z2 and 1 - ((X・θ) / 360 - [(X・θ) / 360]) > 1 / Z2 (where [ ] is the Gaussian symbol).

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