JP2009192022A - Gear device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration control device for suppressing the friction loss of teeth by applying vibration to a gear. <P>SOLUTION: This gear device uses a driving gear 10 and a driven gear 12 meshing with the driving gear 10 for transmitting torque. It comprises a piezoelectric element 20 laid between supporting parts 6, 13 of at least one of the driving gear 10 and the driven gear 12 and adapted to be urged to apply vibration to one gear with a change in the volume, and a controller for urging the piezoelectric element 20 to vibrate one gear while reducing the friction coefficient of the tooth faces of the driving gear 10 and the driven gear 12 meshing with each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gear device that controls vibration of a power transmission mechanism that transmits power output from a power source from an input side gear to an output side gear, and measures the state of the vibration control device using a sensor, The present invention relates to a gear device that controls generated vibrations.

  A gear is known as a general device related to power transmission. In the power transmission by the gear, the input side gear is rotated by the power output from the power source, and the input side gear meshes with the output side gear, so that the power output from the power source is transmitted to the output side gear. Communicated. However, in the power transmission by the gear, since the power is transmitted by the meshing of the gears, vibration and noise are generated.

  Patent Document 1 discloses an invention that suppresses gear vibration by transmitting a vibration synchronized with the gear vibration to the gear in a control device that suppresses the gear vibration. In the apparatus described in Patent Document 1, the piezoelectric element piece is a part of the housing, and the piezoelectric element piece is attached to a site where resonance easily occurs. Therefore, when the piezoelectric element piece is energized, the piezoelectric element is vibrated, and this vibration is transmitted to a site where resonance easily occurs. Therefore, the vibration of the resonating part is suppressed.

JP 2005-344836 A

  On the other hand, when the gear teeth mesh with each other, a relative slip of the meshing teeth occurs. At that time, the relative speed between the meshing teeth becomes the fastest at the tip and root of the teeth and becomes zero at the pitch point. As a result, the relative sliding speed is reduced in the vicinity of the pitch point, and the friction state between the teeth becomes the boundary lubrication region of the Stribeck diagram, so that the friction coefficient is increased. Therefore, the friction loss of the gear increases near the pitch point.

  This coefficient of friction is determined by the viscosity of the oil immersed in the gear, the relative sliding speed of the gear, and the surface pressure of the contact surface of the gear. Therefore, by adjusting the relative sliding speed of the gears, it is possible to adjust the friction coefficient between the gears without adjusting the gears and the mechanisms around the gears. One means for adjusting the relative sliding speed of the gear is a means for applying vibration to the gear, and a means for generating the vibration applied to the gear is a means for generating vibration by energizing the piezoelectric element. It is done.

  The present invention has been made by paying attention to the above technical problem, and an object of the present invention is to provide a gear device that reduces the friction loss of the gear by controlling the relative sliding speed of the gear.

  In order to achieve the above object, a first aspect of the present invention provides a gear device for transmitting torque by a driving gear and a driven gear meshing with the driving gear, and at least one of the driving gear and the driven gear. The friction coefficient of the tooth surface where the drive gear and the driven gear mesh with each other and the piezoelectric element that changes the volume when energized and vibrates to the one gear is reduced. And a controller for energizing the piezoelectric element to vibrate the one of the gears.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect, the controller is configured to estimate the friction coefficient from a sliding speed and a surface pressure of the tooth surface and an oil viscosity of the tooth surface. It is characterized by being.

  According to a third aspect of the present invention, in addition to the configuration of the second aspect, the controller is configured to control the current so as to reduce the friction coefficient.

  According to the first aspect of the present invention, since the piezoelectric element interposed in the support portion of the gear vibrates and this vibration is transmitted to the gear, the friction coefficient of the tooth surfaces of the drive gear and the driven gear is reduced. be able to. Therefore, power transmission efficiency between the drive gear and the driven gear is improved.

  According to the invention of claim 2, in addition to the effect of claim 1, the friction of the tooth surface between the driving gear and the driven gear can be obtained from the sliding speed of the tooth surface, the surface pressure, and the viscosity of the oil on the tooth surface. The coefficient can be estimated. Therefore, it is possible to improve the power transmission efficiency between the drive gear and the driven gear.

  According to the invention of claim 3, in addition to the effect of claim 2, the vibration of the piezoelectric element can be controlled based on the estimated friction coefficient of the tooth surface. Therefore, the vibration of the piezoelectric element can be controlled so that the friction coefficient of the tooth surface is minimized, and the power transmission efficiency between the drive gear and the driven gear is improved.

  Next, the present invention will be described more specifically. FIG. 2 shows a schematic diagram of a transmission as an example of a power transmission mechanism that transmits power output from a power source from an input side gear to an output side gear. The gear used for the power transmission mechanism may be any gear that engages teeth such as a spur gear, a helical gear, a planetary gear, a rack, and a bevel gear.

  The transmission 1 includes a front case 2 connected to a power source (not shown), and a middle case 4 that is attached to the front case 2 on the opposite side of the engine and that houses a gear mechanism 3 and the like. In the front case 2, an input shaft 6 is connected to an output shaft of an engine (not shown).

  Since the input shaft 6 is supported with respect to the middle case 4 via the bearing 11, the rotational movement along the axis is possible. A drive gear 10 is integrated in the middle case 4, and a driven gear 12 is engaged with the drive gear 10. This driven gear 12 corresponds to a driven gear. The driven gear 12 is attached to the counter shaft 13. This countershaft 13 corresponds to the support portion of the driven gear. A plurality of gears are attached to the counter shaft 13, and one of the gears meshes with a ring gear 15 of a differential gear 14 (differential gear device). The output of the differential gear 14 is output to the left and right drive shafts 16L and 16R.

  Next, FIG. 3 schematically shows the meshing portion 17 between the gears in the meshing portion between the drive gear 10 and the driven gear 12 or the meshing portion between the gear attached to the counter shaft 13 and the ring gear 15. In FIG. 3, the following description will be given using an example in which the upper gear 7 rotates counterclockwise and the lower gear 8 rotates clockwise. In addition, the thick line part (black part) of a tooth surface represents the distance from the contact part (meshing point) of gears to a pitch point.

  The tooth shape of the gear is configured so that the tip portion is narrower than the root of the tooth. Therefore, the contact between the gears that occurs during the rotational movement of the gears starts at the tip end portion 18 a of the lower gear 8 and the root portion 19 b of the upper gear 7. The contact state at this time corresponds to FIG. 3A, and the relative sliding speed between the gears becomes maximum at a contact point A where the root portion of the upper gear 7 and the tip end portion of the lower gear 8 are in contact.

  When the gears 7 and 8 rotate from the state of FIG. 3A, the contact portions between the gears approach the pitch points B and C (FIG. 3B). The relative sliding speed between the gears decreases as the contact portion between the gears approaches the pitch points B and C. Further, when the gears 7 and 8 further rotate from the state of FIG. 3B, the gears 7 and 8 come into contact at pitch points B and C (FIG. 3C). At this time, the relative sliding speed between the gears becomes zero.

  When the rotational movement between the gears proceeds from the state of FIG. 3C, the teeth meshing with each other move away (FIGS. 3D and 3E). At this time, the contact between the gears is performed at the root portion 18 b of the lower gear 8 and the tip portion 19 a of the upper gear 7. Therefore, the relative sliding speed between the gears increases as the contact portion between the gears becomes the end of the upper gear 7.

  Further, FIG. 3F shows a state immediately before the teeth are separated from each other by rotating the gears. At this time, the root portion 18b of the lower gear 8 and the tip portion 19a of the upper gear 7 are in contact with each other, and the relative sliding speed between the gears is maximized.

  The friction coefficient related to the friction between the gears depends on the relative sliding speed, the viscosity of the oil immersed in the gear, and the surface pressure of the tooth surface. The relationship is shown in FIG. 4 as a Stribeck diagram. In FIG. 4, the vertical axis represents the friction coefficient between gears, and the horizontal axis represents the Sommerfeld number obtained by multiplying the viscosity of oil by the relative sliding speed and dividing by the surface pressure. The friction state of the gear varies depending on the size of the Sommerfeld number, and the boundary lubrication region, the mixed lubrication region, the fluid lubrication region, and the friction state vary in ascending order of the Sommerfeld number.

  When the Sommerfeld number is small, the friction coefficient is in the boundary lubrication region, and the friction coefficient is a larger value than in other regions. When the Sommerfeld number is larger than the predetermined value a, the friction coefficient is changed from the boundary lubrication region to the mixed lubrication region, and the friction coefficient is rapidly decreased. Further, when the Sommerfeld number further increases, the friction coefficient varies from the mixed lubrication region to the fluid lubrication region at a predetermined value b. At this time, the friction coefficient at the predetermined value b becomes a minimum value. When the Sommerfeld number is larger than the predetermined value b, the friction coefficient increases as the Sommerfeld number increases.

  As described above, the relative sliding speed decreases near the gear pitch points B and C. Therefore, the Sommerfeld number is reduced, and the state of friction between the gears occurs in the boundary lubrication region, and the friction coefficient between the gears is increased. Therefore, forced vibration is applied to the gear in order to reduce the friction coefficient of the gear near the pitch point of the gear.

  As one of means for forcibly applying vibration to the gear 9, there is means for applying vibration to the gear 9 by attaching a piezoelectric element 20 to devices or parts around the gear 9. Since the volume of the piezoelectric element 20 varies due to energization, vibration generated from the piezoelectric element 20 is transmitted to the contact object. One specific example is shown in FIG. FIG. 1 shows a structure in which a piezoelectric element 20 is attached to the outer periphery of a bearing 11 with an input shaft 6 as an axis. When a voltage is applied alternately to the piezoelectric elements 20, the piezoelectric elements 20 vibrate and this vibration is transmitted to the input shaft 6. At that time, the vibration generated from the piezoelectric element 20 is attached so that the vibration component in the axial direction of the input shaft 6 increases. Further, the current supplied to the piezoelectric element 20 is controlled by a controller (not shown). A plurality of gears 9 are attached to the input shaft 6. Therefore, the vibration generated by the piezoelectric element 20 is transmitted to each gear via the input shaft 6, and the vibration is transmitted to the teeth of each gear.

  Since vibration is transmitted to the teeth, the meshing teeth vibrate with each other. This vibration vibrates so that each tooth has a relative speed. As a result, the relative sliding speed increases and the Sommerfeld number increases, thereby reducing the coefficient of friction of the teeth.

  The control for minimizing the tooth friction coefficient is described below. The Sommerfeld number is obtained from the viscosity of the oil filled in the sliding surface of the gear, the relative sliding speed between the teeth, and the surface pressure of the teeth. Here, the viscosity of the oil depends on the component of the oil and the temperature, but usually the viscosity of the oil changes with a change in temperature. For this purpose, a temperature sensor for measuring the temperature is attached. As this temperature sensor, a known sensor such as a thermistor is used.

  The relative sliding speed depends on the tooth angle and the rotational speed of the gear. At this time, a plurality of gears are attached to the input shaft 6 and the counter shaft 13, and the gears attached to the input shaft 6 and the counter shaft 13 are configured to mesh with each other. Therefore, the rotational speed of the gear can be detected by measuring the rotational speed of the input shaft 6 or the counter shaft 13 and the rotational speed of the gear using a rotational speed sensor. The rotation speed sensor may be a sensor that is in contact with any one of the input shaft 6, the counter shaft 13, and the gear that is the object of measurement of the rotation speed, or that is not in contact with either the input shaft 6, the counter shaft 13, or the gear.

  Since the rotational speed of the gear attached to the input shaft 6 or the counter shaft 13 or the respective shafts 6 and 13 is measured by the rotational speed sensor, the rotational speed of the gear attached to the input shaft 6 or the counter shaft 13 is measured. Can know. The rotational speed of the gear attached to the input shaft 6 or the countershaft 13 can be obtained from the rotational speed and the radius of the gear. Further, the angle of the teeth when the gear rotates is measured by an angle sensor. The angle of the teeth is measured with reference to a line connecting the pitch point and the center of the gear, and the angles of the teeth of the gear attached to the input shaft 6 and the gear attached to the countershaft 13 are measured. . The angle sensor may be either a sensor that contacts the gear or a sensor that does not contact the gear. Therefore, as shown in FIG. 3C, when the gears are meshed at the pitch point, the angle measured by the angle sensor is zero. Further, as shown in FIGS. 3A and 3F, when the gears mesh with each other between the tooth tip portions 18a and 19a and the root portions 18b and 19b, the angle measured by the angle sensor becomes large. . And the relative sliding speed of the tooth surface at that time is calculated | required from specifications, such as the rotational speed and tooth angle of this gear, the number of teeth of each gear, a pressure angle, a torsion angle, and a dislocation coefficient.

  Further, the surface pressure between the tooth surfaces can be obtained from the torque of the gear, the angle of the teeth, and the gear stage. Here, the power output from the power source is transmitted from an output shaft (not shown) to the input shaft 6. Therefore, in order to measure the torque generated from the power source, the torque of the input shaft 6 can be measured with a torque sensor, or the torque of the gear can be measured with the torque sensor. The tooth angle is measured by the angle sensor described above.

  For the gear stage, the shift position of a shift lever (not shown) can be measured using a shift position sensor. This shift lever is capable of selecting a travel position that can transmit a driving force generated from a power generation device such as an engine or a motor, and a non-travel position that does not transmit the driving force. This shift lever can transmit this driving force or set the gear ratio of the gear. By using this shift position sensor, it is possible to know the rotation ratio of the meshing gears. If the gear rotation ratio is known, then the gear torque ratio becomes the coefficient, and the above-mentioned measured power source torque and specifications such as the number of teeth of each gear, the pressure angle, the torsion angle, the shift coefficient, and the tooth The surface pressure at that time can be obtained from the angle of.

  The Sommerfeld number is determined from the determined viscosity, relative sliding speed, and surface pressure, and the coefficient of friction between the tooth surfaces can be estimated based on the Sommerfeld number. The estimation of the friction coefficient is estimated by a controller, and the measured temperature, engine speed, tooth angle, torque of the input shaft 6 and shift position are input to the controller.

  This coefficient of friction is minimized when the Sommerfeld number is at the boundary between the mixed lubrication region and the fluid lubrication region. On the other hand, since the relative sliding speed is low near the pitch point of the gear, the required Sommerfeld number may be reduced, resulting in a boundary lubrication region or a mixed lubrication region. At this time, since the friction coefficient is large, by increasing the relative sliding speed, the Sommerfeld number is brought close to the boundary between the mixed lubrication region and the fluid lubrication region, and the friction coefficient of the tooth surface is reduced. Specifically, by energizing the piezoelectric element 20, vibration generated in the piezoelectric element 20 is transmitted to the gear via the input shaft 6. At that time, the piezoelectric element 20 is attached so that the vibration of the piezoelectric element 20 vibrates in the axial direction of the input shaft 6.

  When the vibration of the piezoelectric element 20 is vibrated, noise due to the vibration may occur. For this reason, noise can be suppressed by removing the vibration frequency of the piezoelectric element 20 from the human audible range. Specifically, the frequency to be excited is 15 kHz or more.

  In the first specific example, the vibration from the piezoelectric element 20 is applied to the gear mechanism 3 attached to the input shaft 6, but the piezoelectric gear is attached to the driven gear 12 attached to the counter shaft 13. The thing which gives the vibration from the element 20 may be used. At this time, the countershaft 13 is supported with respect to the middle case 4 via the bearing 11b, and the piezoelectric element 20 is attached to the bearing 11b.

  Next, as a second specific example, instead of the torque sensor and the rotation speed sensor, torque estimation means and other rotation speed calculation means are used to control the relative sliding speed and the surface pressure of the tooth surface. A vibration control device that controls the friction coefficient between them will be described.

  As described above, the relative sliding speed depends on the tooth angle and the rotational speed of the gear. At this time, a plurality of gears are attached to the input shaft 6 and the counter shaft 13, and the gears attached to the input shaft 6 and the counter shaft 13 are configured to mesh with each other. Therefore, when the power source is an engine attached to the vehicle, the engine torque can be obtained by estimation. The engine torque can be estimated from the throttle opening, vehicle acceleration, air temperature, and the like. Further, since the rotational speed of the gear can be estimated based on the engine speed sensor or the vehicle speed sensor and the gear position sensor, the relative sliding speed can be estimated.

  Further, the surface pressure between the tooth surfaces can be obtained from the torque of the gear, the angle of the teeth, and the gear stage. Here, since the gear is attached to the input shaft 6, the torque of the gear can be estimated by estimating the engine torque of an engine (not shown). The tooth angle is measured by the angle sensor described above.

  As for the gear stage, the rotation ratio of the meshing gear can be known by measuring the shift position of a shift lever (not shown) using a shift position sensor. Then, the surface pressure can be obtained from the rotation ratio of the meshing gear, the tooth angle, and the estimated gear torque.

  The Sommerfeld number is estimated from the obtained viscosity, relative sliding speed, and surface pressure, and the coefficient of friction between the tooth surfaces can be estimated based on the Sommerfeld number. This coefficient of friction is minimized when the Sommerfeld number is at the boundary between the mixed lubrication region and the fluid lubrication region. On the other hand, in the vicinity of the gear pitch point, the relative slip speed is small, so that the required Sommerfeld number is small, which may be a boundary lubrication region or a mixed lubrication region. At this time, since the friction coefficient is large, by increasing the relative sliding speed, the Sommerfeld number is brought close to the boundary between the mixed lubrication region and the fluid lubrication region, and the friction coefficient is decreased. Specifically, by energizing the piezoelectric element 20, vibration generated in the piezoelectric element 20 is transmitted to the gear via the input shaft 6. At that time, the piezoelectric element 20 is attached so that the vibration of the piezoelectric element 20 vibrates in the axial direction of the input shaft 6.

  Next, as a third specific example, another example of a power transmission mechanism for power is shown. A schematic diagram of this power transmission mechanism is shown in FIG. Since it is common to the first specific example except for the mounting of the actuator 20, the same reference numerals are given and description thereof is omitted.

  FIG. 5A illustrates a cross-sectional view of a structure in which the piezoelectric element 20 is attached to the outer peripheral portion of the bearing 11 with the input shaft 6 as an axis. When the piezoelectric element 20 is energized, the piezoelectric element 20 vibrates. The vibration at this time is attached so as to vibrate mainly in the radial direction of the input shaft 6, and this vibration is transmitted to the input shaft 6. Further, since the plurality of gears 9 are attached to the input shaft 6, vibration generated by the piezoelectric element 20 is transmitted to each gear 9 via the input shaft 6. And a vibration is transmitted to the tooth | gear at the time of each gear 9 meshing | engaging.

  Since vibration is transmitted to the teeth, the meshing teeth vibrate with each other. This vibration vibrates so that each tooth has a relative speed. As a result, the relative sliding speed increases and the Sommerfeld number increases, thereby reducing the coefficient of friction of the teeth.

  Next, as a fourth specific example, another example of a power transmission mechanism for power will be described. A schematic diagram of this power transmission mechanism is shown in FIG. Since it is common to the first specific example except for the mounting of the actuator 20, the same reference numerals are given and description thereof is omitted.

  FIG. 5B shows a structure in which the piezoelectric element 20 is attached to the gear 9. At this time, the piezoelectric element 20 is attached to the toothless surface of the gear 9. At this time, the piezoelectric element 20 may be attached to the gear 9 on one side or both sides. Thus, when the piezoelectric element is directly attached to the gear 9, the transmission efficiency when transmitting vibration to the tooth surface is improved. Further, since the piezoelectric element 20 is directly attached to the gear 9, a slip ring 30 is required for electrical connection with a fixed power source. The slip ring 30 is attached so as to be laminated with the piezoelectric element 20, and is attached so that the piezoelectric element 20 is sandwiched between the gear and the slip ring 30.

  Note that in both the third specific example and the fourth specific example described above, the energization to the piezoelectric element 20 based on the measured value using the torque sensor and the rotation speed sensor, and the piezoelectric element based on the estimated value by the torque estimating means Any of the energization to 20 is possible.

It is a figure which shows roughly the example which attached this vibration control apparatus. It is a figure which shows roughly an example which used this vibration control apparatus for the transmission. It is the figure which represented the expansion part at the time of the tooth | gear surface of gears meshing | engaging in time series. It is a Stribeck diagram which shows the friction coefficient of a tooth surface. It is a figure which shows roughly the other example which attached this vibration control apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Transmission, 2, 4 ... Case, 3 ... Helical gear apparatus, 6 ... Input shaft, 7 ... Upper gear, 8 ... Lower gear, 9 ... Gear, 10 ... Drive gear, 11, 11b ... Bearing , 12 ... driven gear, 13 ... counter shaft, 15 ... diff ring gear, 17 ... meshing part, 18a, 19a ... tip part, 18b, 19b ... root part, 20 ... actuator (piezoelectric element), 30 ... slip ring.

Claims (3)

In a gear device for transmitting torque by a driving gear and a driven gear meshing with the driving gear,
A piezoelectric element that is interposed in a support portion of at least one of the drive gear and the driven gear and changes its volume when energized to vibrate the one gear;
A gear device comprising: a controller that energizes the piezoelectric element to vibrate the one gear so that a friction coefficient of a tooth surface meshing with the drive gear and the driven gear is reduced.   2. The gear device according to claim 1, wherein the controller is configured to estimate the friction coefficient from a sliding speed and a surface pressure of the tooth surface and a viscosity of oil of the tooth surface.   The gear device according to claim 2, wherein the controller is configured to control the current so as to reduce the friction coefficient.

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