JP5716413B2 - Gear efficiency control device - Google Patents

Description

  The present invention relates to a gear efficiency control apparatus that reduces gear meshing resistance and improves gear efficiency.

  Conventionally, as a method of reducing the frictional force between two contacting solids, at least one contact surface of the two solids is mechanically vibrated at a predetermined frequency to generate a minute relative motion to make contact per unit time. There are technologies that have reduced the frictional force by reducing the area. For example, in the prior art disclosed in Patent Document 1, a predetermined high-frequency vibration is applied to at least one contact surface between two solid bodies, ie, a guide block and a rail, and friction between the track surface of the guide block and the rail track surface is achieved. Power is reduced. At this time, for example, a portion where the rail is supported by the machine body is located at a position corresponding to a node of a high-frequency vibration wave with a small displacement. As a result, only the friction between the raceway surface of the guide block and the rail raceway surface is reduced without the influence of high-frequency vibration on the machine body, etc., and the vibration is minimized without affecting the machine body or workpiece. To improve the positioning accuracy.

  Further, in the prior art disclosed in Patent Document 2, friction between the guide shaft and the bush portion is achieved by applying vibration to one end of the guide shaft between the two solid bodies of the guide shaft and the bush portion provided on the moving lens frame. The force is reduced and the movement is smooth. The smooth movement of the moving lens frame suppresses chattering during movement.

Japanese Patent Laid-Open No. 2005-256594 JP-A-11-160599

  However, in the conventional technique disclosed in Patent Document 1, if there is a fluctuation in the vibration frequency due to a load fluctuation or a change in the temperature characteristics of the vibrating body, a position shift of the node of the high-frequency vibration wave occurs, and the effect decreases. End up. Further, in the conventional technique disclosed in Patent Document 2, the frictional resistance changes because the vibration frequency changes depending on the position of the moving lens frame.

  The present invention has been made in view of the above problems, and provides a gear efficiency control device that can satisfactorily reduce the frictional resistance between two solid bodies with a simple configuration even when there are changes in operating conditions, load fluctuations, and the like. With the goal.

In order to solve the above-described problem, a gear efficiency control device according to a first aspect of the present invention provides a gear set composed of a first gear and a second gear that mesh with each other, and a component in an orthogonal direction with respect to a tooth trace of a meshing portion of the first gear. Vibration means for applying vibration vibration to the first gear to reduce frictional resistance between tooth surfaces of the first gear and the second gear, and a direction in which the vibration means applies the vibration. The elastic member that urges the first gear toward the vibration means in parallel, the first gear, and the second gear mesh, and the first gear is vibrated by the vibration means in a rotating state. A superposed vibration detecting device that detects superposed vibration generated by superimposing on the exciting vibration on the first gear, and the exciting means is configured to minimize the detected superposed vibration. Control the excitation frequency .

To solve the above problems, the gear efficiency control device according to claim 2, Oite to claim 1, wherein the first gear is a worm, the second gear is a worm wheel.

To solve the above problems, the gear efficiency control device according to claim 3, Oite to claim 1 or 2, wherein the vibrating means is constituted by a piezoelectric element for controlling the excitation frequency by changing the input voltage The superposed vibration detection device detects the superposed vibration generated in the first gear from a voltage signal output from the piezoelectric body.

According to the first aspect of the invention, the vibration is applied by the vibration means so that the component in the orthogonal direction is applied to the tooth trace of the meshing portion of the first gear meshing with the second gear. The elastic member urges the first gear in a direction parallel to the direction in which the vibration means applies vibration to the first gear and toward the vibration means. As a result, while the gear set is maintained in a stable meshing state by the elastic member, a minute relative motion is generated between the first gear and the second gear by the vibration vibration, and the contact area per unit time is reduced. The frictional force is reduced. Thus, the frictional force can be reduced at a low cost with a simple configuration. Further, the gear efficiency control device uses the superimposed vibration detection device to determine the magnitude of the superimposed vibration that occurs when the first gear meshes with the second gear and rotates when the first gear is vibrated by the vibration means. To detect. The excitation means controls the excitation frequency for exciting the first gear so that the detected superimposed vibration is minimized. In this way, the feedback control is performed to control the excitation frequency so that the magnitude of the superimposed vibration that is an indicator of a good meshing state between the first gear and the second gear is reduced, so that the gear set is operated under the operating conditions, A good meshing state can be maintained and frictional force can be reduced without being affected by variations in load, changes in temperature characteristics, and the like.

According to the invention of claim 2 , the first gear is a worm and the second gear is a worm wheel. Thus, by applying the present invention between a worm and a worm wheel having a large reduction ratio and a very large frictional force at the meshing portion, a greater effect of reducing the frictional force can be obtained.

According to the invention of claim 3 , the vibration means for controlling the vibration frequency is constituted by a piezoelectric body. The superimposed vibration detection device detects the superimposed vibration generated in the first gear from the voltage signal output from the piezoelectric body, and feedback-controls the excitation frequency by the excitation means so that the superimposed vibration is minimized. As described above, since the piezoelectric body used in the excitation means is also used for detection of the superimposed vibration, the configuration can be simplified and the cost can be reduced.

It is the side surface schematic diagram (a) and the upper surface schematic diagram (b) of the gear efficiency control apparatus 1 which concern on 1st Embodiment. It is a control circuit schematic diagram of a gear efficiency control apparatus. It is an example of the voltage signal which shows the state by which the superimposition vibration Ga was superimposed on the rectangular voltage signal which vibrates the piezoelectric material 20. It is the side surface schematic diagram (a) and the upper surface schematic diagram (b) of the gear efficiency control apparatus 41 which concern on 2nd Embodiment. It is the front schematic diagram (a) which looked at the gear efficiency control apparatus 61 which concerns on 3rd Embodiment from the axial direction of worm, and the upper surface schematic diagram (b) which is a P view of FIG. 5 (a).

  The gear efficiency control device 1 according to the first embodiment of the present invention will be described below. A gear efficiency control device 1 shown in FIG. 1 includes a gear set 10, a piezoelectric body 20 (corresponding to a vibration means in the present invention) that is a vibrating body that vibrates the gear set 10, and an excitation that controls the piezoelectric body 20. It has a vibration device 21, a coil spring 16 (corresponding to an elastic member in the present invention), and a superimposed vibration detection device 30.

  The gear set 10 includes a worm 11 (corresponding to a first gear in the present invention) and a worm wheel 12 (corresponding to a second gear in the present invention) that mesh with each other at a meshing portion. The worm 11 and the worm wheel 12 are general cylindrical worm gears, and the rotation axis of the worm 11 and the rotation axis of the worm wheel 12 are orthogonal to each other. The shaft portion 11c of the worm 11 is rotationally connected to a drive source (not shown). At this time, any drive source may be used, such as a motor rotated by electricity, or an internal combustion engine such as a gasoline engine. The gear set 10 converts the rotation direction of the shaft portion 11 c of the worm 11 and reduces the rotation speed of the worm 11 to transmit the rotation from the drive source to the worm wheel 12.

  As shown in FIG. 1A, the worm 11 has a threaded portion 11 a having a tooth trace A formed at an angle of 90 ° + α ° with respect to the rotation axis of the worm 11 on the cylindrical surface. α ° is an arbitrary angle and may be any angle as long as it is within a range that can be established as a worm. Moreover, the screw formed in the screw part 11a is not limited to a single thread, and may be a multiple thread.

  The worm wheel 12 is a helical gear, and the screw portion 12 a is engaged with the screw portion 11 a of the worm 11. The thread portion 12a of the worm wheel 12 is formed with tooth traces B having an angle of + α ° with respect to the rotational axis of the worm wheel 12 so as to mesh with the thread portion 11a (see FIG. 1B). ). A rotation shaft portion (not shown) of the worm wheel 12 is rotatably supported by a support portion (not shown) included in the gear efficiency control device 1. Further, in the vicinity of the axial direction of the screw portion 11a of the worm 11, an annular portion 11b having a diameter larger than that of the screw portion 11a is formed coaxially with the screw portion 11a.

  As shown in FIG. 1, a bearing 13, which is a ball bearing, supports the shaft portion 11 c of the worm 11 at a position farther from the screw portion 11 a than the annular portion 11 b in the axial direction of the worm 11. The bearing 13 is an inner ring that supports the shaft portion 11c so as to be movable in the axial direction, and the outer ring is fixed to a fixing member (not shown). The fixing member (not shown) is provided in a part of the gear efficiency control device 1 like the worm wheel 12, but is not limited thereto and may be provided in another member. In this embodiment, a ball bearing is applied to the bearing 13. However, the present invention is not limited to this, and a bearing having a configuration in which the outer peripheral surface is fixed to the fixing member and the outer peripheral surface of the shaft portion 11c of the worm 11 is supported by sliding with the inner peripheral surface of the cylindrical through hole may be applied. Good.

  A spacer 14 is provided between the annular portion 11 b of the worm 11 and the bearing 13. One surface 14a of the spacer 14 is slidably in contact with the surface on the bearing 13 side of the annular portion 11b. A piezoelectric body 20 (excitation means) is provided between the spacer 14 and the bearing 13, and the piezoelectric body 20 is in contact with the other surface 14 b of the spacer 14. When a predetermined electrical signal is input and driven, the piezoelectric body 20 is displaced by an amplitude a (for example, several μm) in the axial direction of the worm 11 and vibrates. The amplitude a may be selected as appropriate by the practitioner.

  In this way, when the piezoelectric body 20 is vibrated with the amplitude a by the vibration device 21 shown in FIG. 2 which is the control circuit of the gear efficiency control device 1, the vibration of the piezoelectric body 20 is caused by the spacer 14, the annular portion 11b, And the meshing part (screw part 11a) of the worm 11 is vibrated with the amplitude a through the shaft part 11c. Further, a coil spring 16 as an elastic member according to the present invention is in contact with the flat surface of the annular portion 11a on the screw portion 11a side. The coil spring 16 is contracted between the annular portion 11 b and a support portion (not shown) provided in a part of the gear efficiency control device 1. That is, as shown in FIG. 1A, the coil spring 16 has a worm 11 (first direction) in a direction parallel to and opposite to the direction in which the piezoelectric body 20 that is the vibrating means applies vibration, that is, toward the piezoelectric body 20. The gear is energized.

  As a result, the meshing portion (screw portion 11a) of the worm 11 vibrated by the piezoelectric body 20 is intermittently connected to the meshing portion (screw portion 12a) of the worm wheel 12 while repeating a minute (amplitude a) relative movement at a predetermined frequency. Touch. At this time, since the worm 11 is urged by the coil spring 16 in a direction in contact with the worm wheel 12, the worm 11 intermittently and stably meshes with the worm wheel 12, and rotational force is transmitted from the worm 11 to the worm wheel 12. . In this way, the vibration device 21 is orthogonal to the tooth surface (side surface) of the tooth trace A of the meshing portion of the worm 11 (first gear) at a predetermined frequency as shown in FIGS. An excitation vibration having an amplitude a having a component av is applied. Then, a minute relative motion is generated between the tooth surfaces between the worm 11 and the worm wheel 12, and the contact area per unit time of the meshing portion is reduced to reduce the frictional force.

  1 (a) and 1 (b), the amplitude a and the orthogonal direction component av are displayed in a large vector, but this is schematically drawn and does not show the actual size. Absent. The same applies to FIGS. 4 and 5. In the above, the elastic member is not limited to the coil spring, and any member can be used as long as it can urge the worm 11 toward the piezoelectric body 20 (vibration means). For example, the elastic member has a rubber material or an elastic force. A plate-like metal or the like may be used.

The piezoelectric body 20 converts electrical energy into mechanical energy, and vibrates at a predetermined frequency according to an input voltage. In the present embodiment, the piezoelectric body 20 is a ceramic piezoelectric material, for example, a laminated body of ceramic piezoelectric elements (PbO ₃ , ZrO ₃ , TrO ₃ etc. (PZT type), BaTiO ₃ etc. (BT type)). However, the piezoelectric body is not limited to a ceramic piezoelectric element, and a quartz piezoelectric element (eg, SiO ₂ ) may be applied. Further, lithium tantalate (for example, LiTAO ₃ ), lithium niobate (LiNbO ₃ ), which is a single crystal material, barium titanate (BaTiO ₃ ), which is a polycrystalline material, or the like may be used. Further, an electrostrictive ceramic (such as Pb (Mg _1/3 Nb _2/3 ) O ₃ -PbTiO ₃ (PMN-PT) ceramic) exhibiting a strain proportional to the square of the electric field may be used.

  As illustrated in FIG. 2, the vibration device 21 includes a control unit 22, a frequency controller 23, and an oscillator 24. The frequency controller 23 and the oscillator 24 are controlled by the control unit 22. The control unit 22 includes a CPU, a RAM, a ROM (not shown), and the like that perform calculations. The ROM is a memory that stores a control program and the like. The control unit 22 performs arithmetic processing based on a control program stored in the ROM by the CPU. In the present embodiment, the CPU calculates an excitation vibration frequency fa that minimizes the superimposed vibration Ga based on a detected superimposed vibration Ga described later. And the command signal of the vibration vibration frequency calculated to the frequency controller 23 is transmitted.

The frequency controller 23 receives the result calculated by the control unit 22 and transmits the target value to the oscillator 24.
The oscillator 24 generates a rectangular voltage pulse wave according to the target value transmitted from the frequency controller 23 and applies it to the piezoelectric body 20. As a result, the piezoelectric body 20 imparts an excitation vibration with an amplitude a having an orthogonal component av to the tooth surface (side surface) of the tooth trace A of the meshing portion of the worm 11 at the target vibration vibration frequency fa. The frictional resistance between the tooth surfaces between the worm wheel 12 and the worm wheel 12 is reduced.

  Next, the superimposed vibration detection device 30 will be described. The superimposed vibration detection device 30 includes a control unit 22, a piezoelectric body 20, an oscilloscope 31, a high-pass filter HPF, and an amplifier AMP that are shared with the vibration device 21. The piezoelectric body 20 is the same as and shared with the piezoelectric body 20 as the vibration means. Since the oscilloscope 31, the high-pass filter HPF, and the amplifier AMP are well known, description thereof will be omitted.

  The superimposed vibration detection device 30 detects the vibration of the gear set 10 itself that meshes and rotates by using the piezoelectric body 20 for vibrating the worm 11. That is, the piezoelectric body 20 receives the vibration of the worm 11 through the spacer 14 in contact with the worm 11, and outputs a voltage signal according to the magnitude of the vibration. At this time, as shown in FIG. 3, the vibration signal of the worm 11 is detected by being superimposed on the voltage signal input to the piezoelectric body 20 by the vibration device 21 (hereinafter, the vibration of the gear set 10 itself is referred to as the superimposed vibration Ga. Called).

  Then, the superimposed vibration detection device 30 takes in the voltage signal P on which the superimposed vibration Ga output from the piezoelectric body 20 in accordance with the command of the control unit 22 is extracted, and the superimposed vibration Ga is extracted by the high-pass filter HPF and amplified by the amplifier AMP. . Then, the control unit 22 performs calculation so that the superimposed vibration Ga is minimized and feedback-controls an input voltage signal for exciting and vibrating the piezoelectric body 20, thereby improving the rotational efficiency of the worm 11 and the worm wheel 12. . That is, the vibration frequency fa that avoids the resonance generated in the worm wheel 12 by intermittently contacting the meshing worm 11 and the worm wheel 12 while searching for the inherent resonance frequency of the worm 11 is searched. Is. However, factors other than resonance may be considered as factors that increase the superposed vibration Ga. However, in the present invention, the superposed vibration Ga generated by any factor is controlled by feedback control so that the superposed vibration Ga is minimized, so that the rotational efficiency of the worm 11 and the worm wheel 12 is reliably improved. Can do.

  Next, the operation of the gear efficiency control device 1 will be described. First, the drive source is activated to rotate the worm 11. As a result, the rotational force is transmitted to the threaded portion 12a of the worm wheel 12 that meshes with the threaded portion 11a of the worm 11, the rotational direction of the worm 11 is changed, the rotational speed of the worm 11 is reduced, and the worm wheel 12 rotates. Is done.

Thereafter (or simultaneously), the vibration device 21 is operated. The control unit 22 of the excitation device 21 transmits a command signal having a predetermined excitation vibration frequency fa to the frequency controller 23. The frequency controller 23 transmits the target value commanded from the control unit 22 to the oscillator 24, and the oscillator 24 generates a rectangular pulse wave according to the target value transmitted from the frequency controller 23 and applies it to the piezoelectric body 20. . As a result, the piezoelectric body 20 vibrates at a predetermined vibration vibration frequency fa, and vibrates the worm 11 in the rotation axis direction. As a result, a vibration having an amplitude a having an orthogonal component av is applied to the tooth surface (side surface) of the tooth trace A of the meshing portion of the worm 11 (first gear). Then, the biasing force of the coil spring 16 causes minute relative movement between the tooth surfaces of the worm 11 and the worm wheel 12 where the tooth surfaces are preferably in intermittent contact with each other, thereby reducing the contact area per unit time of the meshing portion. To reduce the frictional force. Thus, if it rotates while meshing in the state which vibrated and vibrated, the frictional force between the tooth surfaces of the worm 11 and the worm wheel 12 will become small, and the gear set 10 can operate | move efficiently.
The number of magnitudes fa of the predetermined vibration vibration frequency may be any number, but the evaluation is performed in advance, and the vibration vibration frequency fa predicted that the worm 11 and the worm wheel 12 can be operated most efficiently. It is preferable to vibrate.

  The superimposed vibration Ga generated in the worm 11 or the worm wheel 12 that is vibrated and vibrated by the vibration device 21 appears as a small value if it deviates from the resonance frequency of the worm 11 or the worm wheel 12, for example. However, if it substantially coincides with the resonance frequency, the value of the superposed vibration Ga is greatly increased, and it cannot be expected that the frictional force between the worm 11 and the worm wheel 12 is reduced to operate efficiently. Therefore, in the present invention, the control unit 22 of the superimposed vibration detection device 30 analyzes and calculates the value of the superimposed vibration Ga, and transmits a command to the vibration device 21 so that the value of the superimposed vibration Ga is equal to or less than the threshold value. The magnitude of the vibration frequency fa is controlled.

  The superposed vibration detection device 30 first takes in the voltage signal P on which the superposed vibration Ga output from the piezoelectric body 20 is superposed by the command of the control unit 22 into the oscilloscope 31 and the high-pass filter HPF at regular intervals (for example, every 20 ms). (See FIG. 3). The high-pass filter HPF separates and extracts the superposed vibration Ga that becomes a high-frequency component.

  The extracted superimposed vibration Ga is amplified by the amplifier AMP, the amplified superimposed vibration Ga is stored in the RAM of the control unit 22, and it is determined whether or not the superimposed vibration Ga needs to be further reduced. If the superposed vibration Ga is smaller than a predetermined threshold value, the control unit 22 continues the vibration at the current vibration vibration frequency fa or increases the vibration vibration frequency fa so as to perform further efficient rotation. . The predetermined threshold here refers to the magnitude of the superimposed vibration Ga that the gear set 10 that has been studied and derived in advance can efficiently rotate. Therefore, the allowable maximum value of the superimposed vibration Ga may be set as a threshold value, or the allowable maximum value + α of the superimposed vibration Ga may be set as a threshold value in consideration of variation in the allowable maximum value, and may be arbitrarily determined by the practitioner.

Further, if the superimposed vibration Ga is larger than a predetermined threshold, the worm 11 or the worm wheel 12 may be resonated. Accordingly, the control unit 22 calculates whether to increase or decrease the vibration vibration frequency fa based on the superimposed vibration Ga data stored in the RAM, and transmits the calculation result (command value) to the frequency controller 23. The frequency controller 23 receives the result calculated by the control unit 22 and transmits an excitation vibration frequency fa that is a target value to the oscillator 24.
The oscillator 24 generates a rectangular voltage pulse wave according to the target value transmitted from the frequency controller 23 and applies it to the piezoelectric body 20. As a result, the piezoelectric body 20 is vibrated at the excitation vibration frequency fa which is a target value.

  At the same time, the superimposed vibration Ga is detected again by the superimposed vibration detection device 30 by the same method as described above. Then, the amplified superimposed vibration Ga is stored in the control unit 22, and it is determined again whether or not the superimposed vibration Ga needs to be further reduced. As a result, if the superimposed vibration Ga is smaller than the predetermined threshold, the control unit 22 can continue the excitation at the current excitation vibration frequency fa, or can further increase the excitation vibration frequency fa to perform further efficient rotation. Control as follows. Further, if the superposed vibration Ga is larger than a predetermined threshold, the control unit 22 computes whether to increase or decrease the vibration vibration frequency fa in order to make the superposition vibration Ga smaller than the threshold, and based on the calculation result, the vibration vibration frequency Change fa.

  In this way, in the present invention, the value of the excitation vibration frequency fa is always feedback-controlled while confirming the magnitude of the superimposed vibration Ga, so the worm 11 (first gear) and the worm wheel 12 (second gear). The resonance frequency can be avoided stably and the gear efficiency between the worm 11 and the worm wheel 12 can be improved even when the resonance frequency of the worm 11 is not clear or when the resonance frequency fluctuates due to operating conditions, load fluctuations, or the like. it can.

  As is clear from the above description, in the first embodiment, the first gear is the worm 11 and the second gear is the worm wheel 12. In this way, by applying the present invention to the worm 11 and the worm wheel 12 having a large reduction ratio and a very large frictional force at the meshing portion, a greater effect of reducing the frictional force can be obtained. In addition, since the piezoelectric body 20 used for the vibration means is also used for detection of the superposed vibration Ga, the configuration can be simplified and the cost can be reduced.

  In the first embodiment, the piezoelectric body 20 (so that a displacement component av in the orthogonal direction is applied to the tooth trace A of the meshing portion of the worm 11 (first gear) meshing with the worm wheel 12 (second gear). Excitation vibration is applied by the excitation means). The coil spring 16 (elastic member) biases the worm 11 in a direction parallel to the direction in which the piezoelectric body 20 applies vibration to the worm 11 and toward the piezoelectric body 20. As a result, while the gear set 10 is maintained in a stable meshing state by the coil spring 16, a minute relative motion is generated between the worm 11 and the worm wheel 12 by the vibration vibration, and the contact area per unit time is reduced and the friction is reduced. Force is reduced. Thus, the frictional force can be reduced at a low cost with a simple configuration.

  Further, in the first embodiment, the gear efficiency control device 1 is configured such that when the worm 11 is vibrated by the piezoelectric body 20, the superimposed vibration Ga generated when the worm 11 meshes with the worm wheel 12 and rotates. The magnitude is detected by the superimposed vibration detection device 30. The magnitude of the excitation frequency fa at which the piezoelectric body 20 vibrates the worm 11 (first gear) is controlled so that the detected superimposed vibration Ga is minimized (below the threshold value). Thus, since the magnitude of the superimposed vibration Ga serving as an index of a good meshing state between the worm 11 (first gear) and the worm wheel 12 (second gear) is controlled, the gear set 10 Can stably reduce the frictional force while maintaining a good meshing state.

  Next, the gear efficiency control apparatus 41 of 2nd Embodiment is demonstrated. The gear efficiency control device 41 according to the second embodiment differs from the gear efficiency control device 1 according to the first embodiment in that the arrangement position of the piezoelectric body 40 that is the vibration means is different, and between the piezoelectric body 40 and the worm 51. Since only the connection method is different, the description of the same part is omitted, and only the different part will be described. Further, parts similar to those of the gear efficiency control device 1 of the first embodiment will be described with the same reference numerals.

  The gear efficiency control device 41 shown in FIG. 4 includes a gear set 50 (worm 51, worm wheel 12), a piezoelectric body 40 that vibrates the gear set 50 (corresponding to the vibration means in the present invention), and a piezoelectric body 40. The vibrating device 21 that vibrates, the coil spring 46 (corresponding to the elastic member in the present invention), and the superimposed vibration detecting device 30 are provided.

As shown in FIG. 4, the worm 51 (first gear) has a threaded portion 51a having a tooth trace C formed at an angle of 90 ° + α ° with respect to the rotational axis of the worm 51 on the cylindrical surface. . The worm wheel 12 (second gear) meshes with the threaded portion 51 a of the worm 51.
In the axial direction of the worm 51, the bearing 13, which is a ball bearing, supports the shaft portion 51 c of the worm 51 on the opposite side from the position where the piezoelectric body 40 is disposed and the screw portion 51 a.
As shown in FIG. 4, the piezoelectric body 40 serving as the vibration means is disposed on the opposite side of the bearing 13 with the screw portion 51 a of the worm 51 as the center. The piezoelectric body 40 is fixed to a support shaft 43 disposed coaxially with the shaft portion 51 c of the worm 51. The support shaft 43 supports the piezoelectric body 40 when the piezoelectric body 40 vibrates, and part of the gear efficiency control device 41 so that the vibration of the piezoelectric body 40 can be transmitted to the worm 51 via a ball 42 described later ( (Not shown).

  Between the support shaft 43 and the worm 51, the metal (for example, stainless steel) ball 42 described above is interposed. The ball 42 is formed between a recess (not shown) formed on the end surface 43a of the support shaft 43 on the worm 51 side and a recess (not shown) formed on the end surface 51d of the worm 51 facing the end surface 43a. Some of them enter each other and are sandwiched so that they can rotate relative to each other. Each recess is formed in an SR (sphere R) shape, and the size of the SR is larger than the size of the SR on the surface of the ball 42. As a result, the ball 42 contacts the SR surface of each recess at a point, and can rotate relative to the worm 51 about the contact point without receiving a large sliding resistance.

  In the vicinity of the end surface 51d of the worm 51, an annular portion 51b having a diameter larger than that of the shaft portion 51c of the worm 51 is formed coaxially with the screw portion 51a. One end surface of the coil spring 46, which is an elastic member, is in contact with the flat surface on the threaded portion 51a side of the annular portion 51b. The other end face of the coil spring 46 is fixed to the same member as the member that fixes the outer periphery of the bearing 13 of the worm 51. As a result, the worm 51 is biased toward the piezoelectric body 40 by the coil spring 46 in parallel with the direction in which the piezoelectric body 40 applies vibration. When the piezoelectric body 40 is vibrated by the vibration device 21, the vibration vibration vibrates the meshing portion (screw portion 51a) of the worm 51 via the support shaft 43, the ball 42, and the shaft portion 51c.

As a result, the meshing portion (screw portion 51a) of the worm 51 vibrated by the piezoelectric body 40 repeats a minute (amplitude a) relative movement at a predetermined frequency in the axial direction of the worm 51, but the meshing portion ( Intermittently contacts the threaded portion 12a). At this time, since the worm 51 is urged by the coil spring 46 in a direction in contact with the worm wheel 12, the worm 51 intermittently and stably meshes with the worm wheel 12, and rotational force is transmitted from the worm 51 to the worm wheel 12. . Thus, as shown in FIGS. 4A and 4B, the vibration device 21 is orthogonal to the tooth surface (side surface) of the tooth trace C of the meshing portion of the worm 51 (first gear) at a predetermined frequency. An excitation vibration having an amplitude a having a component av is applied. Then, a minute relative motion is generated between the tooth surfaces between the worm 51 and the worm wheel 12, and the contact area per unit time of the meshing portion is reduced to reduce the frictional force.
The gear efficiency control device 41 according to the second embodiment is configured as described above, and has the same operational effects as the gear efficiency control device 1 according to the first embodiment.

  Next, the gear efficiency control apparatus 61 of 3rd Embodiment is demonstrated based on FIG. The gear efficiency control device 61 of the third embodiment oscillates the worm 64 that constitutes the gear set 60 by a piezoelectric body 70 as a vibration means, compared to the gear efficiency control devices 1 and 41 of the first and second embodiments. Only the direction is different. Therefore, the description of the same part is omitted, and only the different part will be described. Further, parts similar to those of the gear efficiency control apparatuses 1 and 41 of the first and second embodiments will be described with the same reference numerals.

  As shown in FIG. 5, in the gear efficiency control device 61, the piezoelectric body 70 is fixed to the shaft portion 64d of the worm 64 (first gear) via a cylindrical spacer 67, and the worm 64 is connected to the rotation axis of the worm 64. Vibrates in an orthogonal direction. The spacer 67 rotatably supports the shaft portion 64d of the worm 64 on the inner peripheral surface.

  When the piezoelectric body 70 is vibrated, a vibration having an amplitude a having an orthogonal component av is applied to the tooth surface (side surface) of the tooth trace of the meshing portion of the worm 64, and the worm 64 and the worm wheel 12 (second gear). A slight relative movement occurs between the tooth surfaces and the frictional resistance between the tooth surfaces is reduced.

  At this time, the coil spring 66, which is an elastic member, is disposed 180 degrees opposite to the rotation axis of the worm 64, and urges the shaft portion 64 d of the worm 64 toward the piezoelectric body 70 via the spacer 67. As a result, while the meshing portion of the worm 64 vibrated by the piezoelectric body 70 repeats a minute relative motion, the tooth surface (side surface) of the tooth trace of the meshing portion of the worm 51 is meshed with the worm wheel 12 by the coil spring 66. By being urged in the direction of contact with the tooth surfaces (side surfaces) of the tooth traces, the teeth are stably in intermittent contact and engaged with each other, and the rotational force is transmitted from the worm 11 to the worm wheel 12.

  Since the gear efficiency control device 61 according to the third embodiment is configured as described above, the magnitude of the orthogonal component av with respect to the tooth surface (side surface) of the tooth trace of the meshing portion of the worm 64 is a small value. The gear efficiency control devices 1 and 41 according to the first and second embodiments have corresponding effects.

  In the present embodiment, the voltage signal generated by the oscillator 24 is a rectangular wave. However, the voltage signal is not limited to this and may be a SIN wave. This also provides the same effect.

  In the present embodiment, the vibration means are the piezoelectric bodies 20, 40, and 70, and the superimposed vibration detection device acquires the superimposed vibration Ga output from the piezoelectric bodies 20, 40, and performs feedback control. went. However, the present invention is not limited to this mode, and the superimposed vibration detection apparatus is provided with one piezoelectric body different from the piezoelectric bodies 20, 40, and 70 as the vibration means, and the vibration output from the worms 11, 51, and 64 is detected. You may detect from this another piezoelectric material. Further, the vibration output from the worms 11, 51, 64 may be detected by a vibration detection sensor other than a piezoelectric body such as a G sensor. The same effect can be obtained by these.

  In the present embodiment, the first gear is the worm 11, 51, 64, and the second gear is the worm wheel 12. However, the present invention is not limited to this, and the first gear and the second gear may be a combination of bevel gears or a combination of spur gears. In the combination of these gears, a vibration means (piezoelectric body) is arranged on one gear, and vibration is applied by the vibration means so that a component av in the orthogonal direction is applied to the tooth trace of the meshing portion. Then, a coil spring may be arranged so that one of the excited gears is biased toward the direction of the piezoelectric body in a direction in which the other gear meshes with the other gear. This also provides the same effect.

  In the present embodiment, the superimposed vibration Ga is applied as an index for detecting the meshing state between the worms 11, 51, 64 (first gear) and the worm wheel 12 (second gear). However, the present invention is not limited to this, and sound may be applied as an indicator of the meshing state. That is, if the meshing state between the worms 11, 51, 64 (first gear) and the worm wheel 12 (second gear) deteriorates, the operating noise increases, and if the meshing state becomes good, the operating noise decreases. Therefore, feedback control may be performed using the operation sound as an indicator of the meshing state. The same effect can be expected by this.

  Furthermore, in the first and second embodiments, the coil springs (elastic members) 16 and 46 are arranged on the piezoelectric bodies 20 and 40 side with respect to the meshing portion with the worm wheel 12 in the axial direction of the worms 11 and 51. However, the present invention is not limited to this mode, and the coil springs are arranged in the axial direction of the worms 11, 51 with respect to the piezo-electric bodies 20, 40 centered on the side farther from the piezo-electric bodies 20, 40 than the meshing part with the worm wheel 12. It may be provided on the opposite side. This also provides the same effect.

DESCRIPTION OF SYMBOLS 1, 41, 61 ... Gear efficiency control apparatus 10, 50, 60 ... Gear set, 11, 51, 64 ... 1st gear (worm), 12 ... 2nd gear (worm wheel), 13 ... Bearing, 14, 67 ... Spacer, 16, 46, 66 ... elastic member (coil spring), 20, 40, 70 ... vibration means (piezoelectric body), 21 ... vibration device, 22 ... control unit, 23 ... frequency controller, 24 ... oscillator, 30 ... superimposed vibration detection device, 42 ... ball, 43 ... support shaft.

Claims (3)

A gear set comprising a first gear and a second gear meshing with each other;
Exciting vibration having an orthogonal component to the tooth trace of the meshing portion of the first gear is applied to the first gear to reduce the frictional resistance between the tooth surfaces of the first gear and the second gear. Vibration means;
An elastic member that urges the first gear toward the vibration means parallel to a direction in which the vibration means applies the vibration;
When the first gear and the second gear mesh with each other and the first gear is vibrated by the vibration means in a rotating state, superimposed vibration generated on the first gear is superimposed on the vibration. A superimposed vibration detection device to detect;
Have
A gear efficiency control device in which the excitation means controls the excitation frequency so that the detected superimposed vibration is minimized . Oite to claim 1, wherein the first gear is a worm, the second gear is a gear efficiency control device is a worm wheel. In claim 1 or 2 ,
The excitation means is a piezoelectric body that controls the excitation frequency by changing an input voltage,
The superimposed vibration detection device is a gear efficiency control device that detects the superimposed vibration generated in the first gear from a voltage signal output from the piezoelectric body.

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