JP2006258793A - Torque detector, and bearing unit for supporting pinion shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque detector capable of detecting auxiliary steering force without deteriorating rigidity of a steering shaft in a power steering device, and capable of detecting a torque without affecting a power transmission portion unfavorably in various power transmissions, and a bearing unit for supporting a pinion shaft. <P>SOLUTION: This torque detector is provided with sensors 17, 18 for finding bearing loads acting on rolling bearings 15, 16 for supporting the pinion shaft 14, and a processing means 19 for finding the torque acting on the pinion shaft 14, based on the bearing loads obtained by the sensors 17, 18. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a torque detection device suitably used in a rack and pinion power steering device, a power transmission device, and the like, and a pinion shaft support bearing device incorporating such a torque detection device.

As a power steering device for an automobile, a steering shaft whose one end is fixed to a handle as an operation means for turning left and right wheels, and a rack and pinion mechanism provided between the other end of the steering shaft and the left and right wheels, It is well known that a torque sensor for detecting a steering torque applied to the steering shaft by the operation of the steering wheel and a motor for generating a steering assist force for reducing the driver's load by the steering wheel operation are known. (For example, Patent Document 1). In such a power steering device, in order to easily detect the steering torque, the steering shaft and the pinion shaft are not connected directly to the pinion shaft but via a torsion bar formed so as to be easily twisted. And a torque sensor was attached to this torsion bar.
JP 2004-216951 A

  According to the power steering device of Patent Document 1, the steering shaft and the pinion shaft are connected via a torsion bar that is easily twisted, so that there is a problem in that the shaft rigidity is lowered and the steering feeling is deteriorated.

  On the other hand, in a power transmission device such as a differential device or a transfer device of an automobile, it is difficult to detect torque because it may adversely affect the power transmission portion with the installation of the torque sensor.

  An object of the present invention is to enable detection of steering assist force in a power steering device without reducing the rigidity of the steering shaft, and in various power transmission devices, torque without adversely affecting the power transmission portion. It is an object of the present invention to provide a torque detection device and a pinion shaft support bearing device that can detect the above.

  A torque detection device according to the present invention includes a sensor for obtaining a bearing load acting on a rolling bearing that supports the torque detection shaft, and a processing means for obtaining a torque acting on the torque detection shaft from the bearing load obtained by the sensor. Is.

  The torque detection axis means a symmetrical axis for detecting torque, and is, for example, a pinion axis provided with a pinion at one end. A pair of rolling bearings that support the torque detection shaft is usually provided, and at least one sensor is provided on at least one rolling bearing. The processing means stores an arithmetic expression for obtaining the torque acting on the shaft from the output of the sensor, that is, the load acting on the rolling bearing. This arithmetic expression can be obtained theoretically, or can be obtained experimentally using a torque sensor as a sensor for verification.

  A pinion shaft serving as a torque detection shaft is used in a power steering device for automobiles and various power transmission devices, and this torque device can be applied to any of such devices. Examples of the power transmission device include an automobile differential gear device, a transfer device, and a transmission device. The application of the torque detection device is not limited to automobiles, and can be used for machine tools and the like.

  A pinion shaft support bearing device according to the present invention is a pinion shaft support bearing device having a rolling bearing that rotatably supports a pinion shaft having a pinion disposed at one end thereof, wherein the bearing load acting on the rolling bearing is reduced. It further comprises a sensor to be obtained and a processing means for obtaining a torque acting on the pinion shaft from a bearing load obtained by the sensor.

  The pinion disposed on the pinion shaft may be formed so as to mesh with the rack, and may be formed so as to mesh with the bevel gear.

  For example, in an automobile, a power transmission device, which is referred to as a final gear device, a differential gear device, a transfer device, or the like and transmits driving torque from a rotational drive source such as an engine to a driven shaft, is used. The final gear device includes a pinion shaft in which a pinion is disposed at one end and a driving torque from the engine is transmitted, and a pair of rolling bearings that rotatably support the pinion shaft on a differential carrier. The differential gear device includes a pinion shaft rotatably supported by a differential carrier and having a pinion disposed at one end thereof, a ring gear meshed with the pinion, and a ring.・ Equipped with a differential case attached to the gear and a pair of rolling bearings that rotatably support the differential case on the differential carrier. The transfer device is a pinion. It is provided at one end of the shaft to the ring gear for driving the rear wheel In a four-wheel drive vehicle, power is applied from the engine disposed on the front side of the vehicle to the rear wheels. The pinion shaft includes a pinion shaft coupled to the propeller shaft, and a rolling bearing that rotatably supports the pinion shaft on the casing. The pinion shaft support bearing having a pinion shaft having a pinion disposed at one end and a pair of rolling bearings for rotatably supporting the pinion shaft as a basic configuration. I have a device.

  The pinion shaft support bearing device according to the present invention is suitably used in the power transmission device described above, and has a built-in torque detection device. Therefore, the conventional pinion shaft support bearing device is the one according to the present invention. By replacing, torque in various power transmission devices can be detected. In the power transmission device, when a torque sensor is provided on the pinion shaft, not only the problem that the number of parts increases, but also the power transmission function such as a decrease in strength due to the sensor installation may be affected. The pinion shaft supporting bearing device according to the present invention can be used with the pinion shaft having the same shape as the conventional one, and the reliability of the power transmission device does not deteriorate.

  The pinion shaft support bearing device according to the present invention is also preferably used in a pinion shaft support bearing device used in a rack and pinion type power steering device. In this case, the pinion shaft is connected to the steering shaft and the torsion bar. The processing means has a steering assist force calculation unit that obtains a steering assist force for the driver's steering operation from the output of the sensor. Can eliminate the torsion bar that causes the deterioration.

  In the above torque detection device and pinion shaft support bearing device, the sensor, for example, uses the force acting between the rolling element and the fixed wheel or between the fixed wheel and the housing holding the same as an echo ratio or echo intensity. Although it is an ultrasonic sensor to detect, it is not limited to this, and may be an MI sensor (magnetic impedance sensor) that detects the amount of strain due to the force acting on the fixed ring from the rolling element, and other loads. It may be a sensor (including a stress sensor and a strain sensor). The sensor may be provided on the fixed ring to detect a force acting between the rolling element and the fixed ring. The sensor may be provided on a housing that holds the fixed ring and from the rolling element that acts on the housing via the fixed ring. The force of may be detected. The number and arrangement of sensors are appropriately changed depending on the intended use. For example, when there is a pair of pinion shaft supporting rolling bearings, one of the rolling bearings may be provided, or one each of the pinion shaft supporting rolling bearings may be provided, and one rolling bearing may be provided. Two or more sensors may be provided.

  The ultrasonic sensor obtains the reflected echo of the ultrasonic wave by receiving the reflected wave of the ultrasonic wave output from the vibrator, and when the load acting on the rolling element is large, the contact area becomes large, The reflected wave becomes smaller. Therefore, the bearing load can be obtained from the reflected echo.

  The output of the ultrasonic sensor is obtained, for example, as an echo ratio shown below.

Echo ratio = 100 × (H0−H1) / H0
H0: Reflected echo intensity when the rolling element is separated from the ultrasonic sensor by a half pitch H1: Reflected echo intensity when the rolling element is located immediately below the ultrasonic sensor When the load acting on the pinion shaft supporting rolling bearing changes, The echo ratio changes with the load change. Since the relationship between the echo ratio and the load acting on the bearing can be obtained in advance, the load acting on the rolling bearing can be obtained from the echo ratio by obtaining this relationship experimentally, for example. Thus, the load acting on the rolling bearing without using a torsion bar with reduced rigidity for facilitating torque detection and without applying special processing to the contact portion between the fixed ring and the rolling element. Therefore, torque acting on the torque detection shaft can be obtained.

  The bearing load is preferably determined from an echo ratio obtained by the following equation.

Echo ratio = 100 × (H0−H1) / H0i
H0: Reflected echo intensity when the rolling element is separated from the ultrasonic sensor by a half pitch H1: Reflected echo intensity when the rolling element is located immediately below the ultrasonic sensor H0i: The rolling element at a predetermined temperature is separated from the ultrasonic sensor by a half pitch In the latter echo ratio, the reflected echo intensity when the rolling element at a predetermined temperature (for example, normal temperature) is separated from the ultrasonic sensor by a half pitch is used as the denominator. The reflection echo intensities H0 and H1 in the ultrasonic sensor both depend on the temperature, but (H0−H1) does not substantially depend on the temperature. In the former echo ratio, this temperature-independent (H0-H1) is divided by the temperature-dependent H0, so that the temperature dependence is relatively high. On the other hand, the latter echo ratio makes it possible to make use of the correlation between the echo ratio and the load by making the denominator a term independent of temperature, and to eliminate the temperature dependence.

  When the bearing load is obtained by the ultrasonic sensor, the echo intensity can be used instead of the echo ratio. The echo intensity obtained by the ultrasonic sensor varies depending on the position of the rolling element even when the bearing load is the same. That is, when a constant bearing load is applied, the reflected echo intensity is minimized when the rolling element is located directly below the ultrasonic sensor, and the reflection is reflected when the rolling element is separated from the ultrasonic sensor by a half pitch. The echo intensity is maximized. Therefore, by paying attention to the minimum value of the reflected echo intensity and obtaining the correlation between the desired torque and the minimum echo intensity value, the torque can be detected using the echo intensity.

  A power steering device according to the present invention rotates via a rack shaft supported in an axially movable manner in a rack housing extending in the left-right direction of the vehicle body and at least one rolling bearing inside the pinion housing intersecting the rack housing. In a power steering apparatus including a pinion shaft that is supported and a torque detection device that obtains torque necessary for steering operation, the torque detection device is the torque detection device described above, and the steering shaft is a pinion shaft It is connected without using a torsion bar, and the processing means has a steering assisting force calculation unit for obtaining a steering assisting force for a driver's steering operation from the output of the sensor. .

  According to this power steering device, when a steering operation is performed, the wheel turns, and torque acts on the pinion shaft by the force acting on the tire from the ground at this time. Since the load acting on the pinion shaft support rolling bearing changes due to this torque, the torque acting on the pinion shaft can be obtained by detecting this change in load with an appropriate sensor. Since the torque acting on the pinion shaft corresponds to the steering force, the steering force to be applied by the driver is reduced by giving the steering mechanism a steering assist force according to the magnitude of the load acting on the rolling bearing. Is done.

  The power steering device may be a hydraulic type that generates hydraulic pressure by the rotation of the engine and applies this hydraulic pressure to the steering mechanism, and also provides the necessary assisting force to the steering mechanism by driving the electric motor. An electric type may be used. Specifically, the present invention can be applied to power steering devices such as column type electric power steering, rack coaxial type electric power steering, step orifice type electronic control type power steering, electric pump type hydraulic power steering and the like.

  The power assist unit including the motor may be provided on the pinion shaft (pinion assist type) or may be provided on the rack shaft (rack assist type). In the latter case, the number of motors may be plural. In the pinion assist type, the sum of the driver's steering torque and the motor auxiliary torque acts between the pinion and the rack teeth. In the rack assist type, the driver's steering torque is between the pinion and the rack teeth. Only the steering torque works. In any case, torque acting between the pinion and the rack teeth is obtained from the sensor output.

  When the sensor is an ultrasonic sensor and the power steering device is a rack assist type (further provided with a motor that moves the rack shaft directly in the axial direction), the processing means specifically includes, for example, an ultrasonic sensor. Detection value extraction means for extracting the echo intensity minimum value as a detection value from the echo waveform output from the motor, comparison means for comparing whether the detection value is larger or smaller than the threshold value, and a motor when the detection value is less than the threshold value Steering assistance mode control means for outputting an operation signal and outputting a motor stop signal when the detected value is larger than a threshold value is provided.

  According to the torque detection device and the pinion shaft support bearing device of the present invention, when applied to a power steering device, it is possible to accurately detect a power steering torque for obtaining a steering assist force without using a torsion bar. Therefore, it is possible to detect the steering assist force without reducing the rigidity of the steering shaft, and it is possible to prevent the deterioration of the steering feeling due to the reduction of the shaft rigidity. In addition, when applied to various power transmission devices, it becomes possible to detect torque without adversely affecting the power transmission portion, and without reducing the reliability of the power transmission device, A torque suitable for knowing the performance can be detected.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, left and right and top and bottom refer to left and right and top and bottom of FIG.

  FIG. 1 shows a first embodiment in which a torque detection device and a pinion shaft support bearing device according to the present invention are applied to a power steering device.

  The power steering device (1) includes a steering shaft (4) whose upper end is fixed to a handle (steering wheel) (3) as an operation means for turning the left and right wheels (2), and the steering shaft (4) The rack and pinion mechanism (5) provided between the lower end of the wheel and the left and right wheels (2), and the steering provided on the rack and pinion mechanism (5) and applied to the steering shaft (4) by operating the handle (3) A torque detection device (6) for detecting torque, an electric motor (7) for generating a steering assist force for reducing a driver's load (steering force) by a steering operation (steering operation), and the motor (7) A reduction gear (8) that transmits the steering assist force generated by the engine to the steering shaft (4), and a sensor from the torque detection device (6) and the vehicle speed sensor (20) that receives power from the vehicle-mounted battery (9) An electronic control unit that controls the drive of the motor (7) based on the signal A knit (ECU) (10).

  As shown in detail in FIG. 2, the rack and pinion mechanism (5) includes a rack housing (11) extending in the left-right direction of the vehicle body, and an axial direction (left-right direction in FIG. 1, FIG. 2) in the rack housing (11). A rack shaft (12) supported movably in a direction perpendicular to the paper surface, a pinion housing (13) provided to intersect the rack housing (11), and rotatable inside the pinion housing (13) And a supported pinion shaft (14).

  The torque detection device (6) obtains a bearing load acting on at least one of the rolling bearings (16) and a pair of upper and lower rolling bearings (15) and (16) supporting a pinion shaft (14) as a torque detection shaft. At least one sensor (17) (18) and a processing means (19) for obtaining a torque acting on the pinion shaft (14) from the bearing load obtained by the sensor (17) (18) are provided.

  The rotation of the motor (7) is transmitted to the steering shaft (4) via the reduction gear (8), and the rotation of the motor (7) is connected to the pinion shaft (14) connected to the lower end of the steering shaft (4). The handle operation is assisted by applying the force.

  The rack shaft (12) has rack teeth (12a) formed at the intersection with the pinion housing (13). Both end portions of the rack shaft (12) are protruded from the rack housing (11), and the left and right wheels (2) are connected to the protruding portions via tie rods (21).

  The pinion shaft (14) has a pinion (14a) that meshes with the rack teeth (12a) of the rack shaft (12) at the intersection with the rack housing (11). The upper part of the pinion shaft (14) is projected from the pinion housing (13) and is connected to the steering shaft (4). The pinion shaft (14) is configured to rotate clockwise or counterclockwise according to the operation of the handle (3).

  In the conventional power steering device, a rack and pinion mechanism (5) is provided by an input shaft connected at the upper end to the handle (3), an output shaft connected to the pinion, and a small-diameter torsion bar connecting the two shafts. ) And the steering wheel (3) are configured. On the other hand, in the power steering device (1) of this embodiment, the steering shaft (4) and the pinion shaft (14) are provided with a torsion bar. It is connected directly without going through.

  The upper and lower rolling bearings (15), (16) are fixed to the outer ring (15a) (16a), the inner ring (15b) (16b) as a rotating ring, the balls (15c) (16c) as rolling elements, and the cage. (15d) and (16d) angular contact ball bearings, which rotatably support the pinion shaft (14) on the pinion housing (13) and the backlash of the pinion shaft (14) inside the pinion housing (13). Prevents sticking.

  There are two sensors (17) and (18) attached to the outer ring (16a) of the lower rolling bearing (16) so as to sandwich the pinion shaft (14) from both sides in the longitudinal direction of the rack shaft (12). Yes. These sensors (17) and (18) are ultrasonic sensors so that the force (bearing load) acting between the outer ring (16a) and the ball (16c), which is a fixed ring, can be detected. As shown in FIG. 2, it is inserted from a through hole (13a) provided in the pinion housing (13) into a bottomed hole (16e) provided in the outer ring (16a) of the rolling bearing (16), and the outer ring (16a ) And the ball (16c).

  The ultrasonic sensors (17) and (18) obtain the reflected echo as shown in FIG. 3 by receiving the reflected wave of the ultrasonic wave output from the vibrator at the receiving unit, and the output is as follows. Calculated as the echo ratio.

Echo ratio = 100 × (H0−H1) / H0
H0: Echo intensity when the rolling element is separated from the ultrasonic sensor by a half pitch H1: Echo intensity when the rolling element is located immediately below the ultrasonic sensor This echo ratio is shown in FIG. The bearing load can be obtained from the echo ratio using this relationship. If the load acting on the ball (16c) is large, the contact area becomes large and the reflected wave becomes small. Therefore, when the bearing load is large, a large echo ratio is output.

  The echo ratio for obtaining the bearing load may be obtained as follows by performing temperature correction.

Echo ratio = 100 × (H0−H1) / H0i
H0: Reflected echo intensity when the rolling element is separated from the ultrasonic sensor by a half pitch H1: Reflected echo intensity when the rolling element is located immediately below the ultrasonic sensor H0i: The rolling element at a predetermined temperature is separated from the ultrasonic sensor by a half pitch Reflected echo intensity at the time of processing The processing means (19) includes an equation for the echo ratio, an equation for obtaining the bearing load at the sensor position from the echo ratio obtained from each ultrasonic sensor (17), (18), these bearing loads Formulas for obtaining the steering torque acting on the steering shaft (4) are stored.

  When the driver operates the steering wheel, the pinion shaft (14) connected to the steering shaft (4) rotates, and this rotation is caused by the pinion (14a) and the rack teeth (12a) to be the axis of the rack shaft (12). This movement is converted into a directional movement, and this movement is transmitted to the left and right wheels (2) via the tie rods (21). Along with this, the steering torque acting on the steering shaft (4) increases, and the magnitude is obtained in the processing means (19) using the bearing load obtained by the sensors (17) and (18). The magnitude of the steering torque corresponds to the magnitude of the driver's load due to the steering wheel operation. Therefore, the steering assist force for reducing the driver's load due to the steering wheel operation is obtained from the bearing load, and this result is obtained from the ECU (10). By applying to the motor (7) via the required steering assist force, the motor (7) can generate a necessary steering assist force, and an appropriate steering assist force can be applied to the steering mechanism of the vehicle.

  As described above, the bearing device for supporting the pinion shaft used in the power steering device (1) is a rolling bearing (15) that rotatably supports the pinion shaft (14) having the pinion (14a) disposed at one end thereof. ) (16), sensors (17) (18) for determining the bearing load acting on the rolling bearing (16), and the torque acting on the pinion shaft (14) from the bearing load obtained by the sensors (17) (18) And processing means (19) for obtaining

  The pinion shaft support bearing device configured as described above can be applied not only to the power steering device (1) but also to various power transmission devices.

  The power steering device (1) of the first embodiment is of a so-called pinion assist type that transmits the steering assist force generated by the electric motor (7) to the steering shaft (4) via the reduction gear (8). However, the torque detection device (6) can of course be applied to a so-called rack assist type as shown below.

  FIG. 5 shows a second embodiment in which the torque detection device and the pinion shaft support bearing device according to the present invention are applied to a power steering device. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the power steering device (22) of the second embodiment, the output rotation of the electric motor (23) is reduced to the axis of the rack shaft (12) via the speed reduction mechanism (27) (28) and the motion conversion mechanism (24) (25). It is converted into a directional movement, and as a result, steering assistance is achieved.

  Specifically, a screw shaft (24) is formed at an axially intermediate portion of the rack shaft (12), and a rotating cylinder (25) made of a ball nut is concentrically surrounded around the screw shaft (24). is doing. The rotary cylinder (25) is rotatably supported by a rack housing (not shown) via a pair of rolling bearings (26), and movement in the corresponding axial direction is restricted by the bearing (26). Has been. A drive bevel gear (27) is provided on the output shaft of the motor (23), and a driven bevel gear (28) meshed with the drive bevel gear (27) around the rack shaft (12). Is provided. The rotating cylinder (25) is integrated with the driven side bevel gear (28) and screwed onto a screw shaft (24) formed on the rack shaft (12) via a rolling element (not shown).

  The processing means (19) of the power steering device (22) of the second embodiment includes detection value extraction means for extracting the echo intensity minimum value as a detection value from the echo waveform output from the ultrasonic sensors (17) and (18). Steering device for comparing whether the detected value is larger or smaller than the threshold value, and outputting a motor operation signal when the detected value is less than the threshold value, and outputting a motor stop signal when the detected value is larger than the threshold value And auxiliary mode control means.

  The positional relationship of the rolling bearing (16) with respect to the pinion housing (13) is such that the outer ring (16a) of the rolling bearing (16) is concentrically supported by the pinion housing (13) as shown in FIG. 6 (a). = The handle (3) is in the neutral position and the outer ring (16a) of the rolling bearing (16) is eccentrically supported by the pinion housing (13) as shown in FIG. 6 (b) = the handle ( 3) is operated, and as shown in FIG. 6 (b), the ball (16c) is located directly below the ultrasonic sensor (18), and as shown in FIG. 6 (c), There is a state in which the balls (16c) are separated from the ultrasonic sensor (18) by a half pitch.

  The echo waveform output from the ultrasonic sensor (18) corresponding to the above-described FIGS. 6 (a), (b) and (c) is as shown in FIG. That is, when the handle (3) is in the neutral position = when no load is applied to the rolling bearing (16), the reflected echo intensity is the highest as shown by (1) in FIG. When the handle (3) rotates from the neutral position, the surface pressure acting on the mating surface between the outer ring (16a) and the pinion housing (13) increases as the load acting on the rolling bearing (16) increases. The transmittance of the echo increases, thereby reducing the echo intensity (decreases to (2) in FIG. 7). Even if the surface pressure acting on the outer ring (16a) is the same, the echo intensity also changes depending on the position of the ball (16c). (2) in FIG. 7 corresponds to FIG. 6 (b), and shows that the reflected echo intensity is minimized when the ball (16c) is located directly below the ultrasonic sensor (18). 7 (3) corresponds to FIG. 6C, and shows that the reflected echo intensity is maximized when the ball (16c) is separated from the ultrasonic sensor (18) by a half pitch. . Further, the echo waveform shown in FIG. 7 (b) shows a case where the load acting on the rolling bearing (16) is larger than that shown in FIG. 7 (a). Finally, focusing on the minimum echo intensity, the steering torque and the minimum echo intensity have a linear correlation as shown in FIG. Therefore, when the first echo intensity minimum value is smaller than the specified threshold value, the electric motor (23) is operated, and then this echo intensity minimum value is sequentially rewritten with the next echo intensity minimum value, and the next minimum value is reached. Is smaller than the prescribed threshold value, the electric motor (23) is continuously operated, and when the minimum value is larger than the prescribed threshold value, the electric motor (23) may be stopped.

  Based on the above knowledge, in the processing means (19), the electric motor (23) is actuated / stopped by the steps shown in FIG. The threshold value Eth for the minimum echo intensity is set in advance (step 1 (S1)). When the automobile is started, the electric motor (23) of the power steering device (22) (hereinafter referred to as “auxiliary motor”). Is stopped (step 2 (S2)). At the start of the automobile, the ultrasonic sensors (17) and (18) start detecting the echo intensity, and the minimum value extracting means obtains the echo intensity minimum value detected value Emin from the sensor output (step 3 (S3)). The comparing means uses the echo intensity minimum value detection value Emin and the echo intensity minimum value threshold Eth to compare the magnitude relationship (step 4 (S4)). Here, if the echo intensity minimum value detection value Emin is less than or equal to the echo intensity minimum value threshold Eth, it is determined that the steering is necessary because the force acting on the rolling bearing (16) is large, and the steering assist mode. The auxiliary motor (23) is operated by the motor operation signal output from the control means (step 5 (S5)). If the echo intensity minimum value detection value Emin is larger than the echo intensity minimum value threshold Eth, the force acting on the rolling bearing (16) is small. The motor (23) cannot be operated. In this case, the process returns to step 3 (S3) to continue monitoring the echo intensity. In step 4 (S4), when the echo intensity minimum value detection value Emin is less than or equal to the echo intensity minimum value threshold Eth, the operation of the auxiliary motor (23) is continued (step 5 (S5)) and the auxiliary motor (23) In order to determine whether or not to stop the operation, monitoring of the sensor output is continued (step 6 (S6)). If the echo intensity minimum value detection value Emin is greater than the echo intensity minimum value threshold Eth (step 7 (S7)), the force acting on the rolling bearing (16) is reduced, so the auxiliary steering force is It is determined that it is unnecessary, and the auxiliary motor (23) is stopped by the motor stop signal output from the steering assist mode control means (step 8 (S8)). Thereafter, the process returns to step 3 (S3), the sensor output monitoring is continued, and the operation / stop of the auxiliary motor (23) is repeated according to the magnitude of the steering torque.

  FIG. 10 shows an embodiment in which the torque detection device and the pinion shaft support bearing device according to the present invention are applied to a final reduction gear as an example of a power transmission device.

  The final reduction gear has a final gear device (A) and a differential gear device (B).

  The final gear device (A) meshes with the drive pinion (33) and the pinion shaft (32), which is rotatably supported by the differential carrier (31) and has a drive pinion (33) disposed at the rear end. And a pinion shaft support bearing device (40) for rotatably supporting the pinion shaft (32) on the differential carrier (31).

  The pinion shaft support bearing device (40) includes a pair of rolling bearings (41) rotatably supporting a pinion shaft (32) having a drive pinion (33) disposed at one end thereof, and a drive pinion (33). Sensor (42) (43) for determining the bearing load acting on the rolling bearing (41) on the side close to the shaft, and the torque acting on the pinion shaft (32) from the bearing load obtained by the sensors (42) (43) And processing means (not shown).

  Each of the rolling bearings (41) is a tapered roller bearing, and the sensors (42) and (43) are ultrasonic sensors, and the tapered roller bearing (41) on the side close to the drive pinion (33) is left and right 1 It is provided in pairs.

  Each ultrasonic sensor (42) (43) passes from the through hole (31a) provided in the differential carrier (31) to the bottomed hole (41e) provided in the outer ring (41a) of the tapered roller bearing (41). The bearing which is inserted and faces the contact surface with the outer ring (41a) and (41c) and acts between the outer ring (41a) and (41c) which is a fixed ring by the same principle as the first embodiment. The load can be detected. Torque is obtained by sensors (42) and (43) for determining the bearing load and processing means for determining torque acting on the pinion shaft (32) as a torque detection shaft from the bearing loads obtained by the sensors (42) and (43). The detection device is configured, and the processing means includes an echo ratio equation, an equation for obtaining a bearing load at the sensor position from the echo ratio obtained from each ultrasonic sensor (42) (43), and a pinion shaft ( The torque that acts on the pinion shaft (32) can be obtained by storing an equation for obtaining the torque that acts on the pinion shaft (32).

  The differential gear unit (B) is for the differential case (35) attached to the ring gear (34) and the pinion shaft support that rotatably supports the differential case (35) on the differential carrier (31). A bearing device (50), a side pinion (37) disposed on the inner end of the left and right pinion shafts (36) extending from the differential case (35) to the left and right, and a spider (39) are rotatably supported. And a differential pinion (38) meshed with the side pinion (37).

  The pinion shaft support bearing device (50) includes a pair of left and right rolling bearings (51) that rotatably supports a pinion shaft (36) having a side pinion (37) disposed at one end thereof, and a rolling bearing (51 ) From the sensors (52) and (53) for determining the bearing load that acts on the pinion shaft (36) from the bearing loads obtained by the sensors (52) and (53). Become.

  Each rolling bearing (51) is a tapered roller bearing, and each of the sensors (52) and (53) is an ultrasonic sensor, and is provided for each of the left and right tapered roller bearings (41).

  Each ultrasonic sensor (52) (53) passes from the through hole (35a) provided in the differential case (35) to the bottomed hole (51e) provided in the outer ring (51a) of the tapered roller bearing (51). The bearing which is inserted and faces the contact surface with the outer ring (51a) and (51c) and acts between the outer ring (51a) and (51c) which is a fixed ring according to the same principle as the first embodiment. The load can be detected. Torque is obtained by sensors (52) and (53) for determining the bearing load and processing means for determining torque acting on the pinion shaft (36) as a torque detection shaft from the bearing load obtained by the sensors (52) and (53). The detection device is configured, and the processing means includes an echo ratio equation, an equation for obtaining the bearing load at the sensor position from the echo ratio obtained from each ultrasonic sensor (52) (53), and the pinion shaft ( The torque that acts on the pinion shaft (36) can be obtained by storing an equation for obtaining the torque acting on 36).

  In each of the above embodiments, the number of ultrasonic sensors (17) (18) (42) (43) (52) (53) used in one pinion shaft support bearing device is two each. However, the number and arrangement are not limited to this. The ultrasonic sensors (17) (18) (42) (43) (52) (53) are provided on the outer rings (16a) (41a) (51a) of the rolling bearings (16) (41) (51). Inserted into the bottomed hole (16e) (41e) (51e) and faced to the contact surface between the outer ring (15a) (16a) (41a) (51a) and the rolling elements (16c) (41c) (51c). However, the holes (13a), (31a) and (35a) provided in the members (13), (31) and (35) for holding bearings such as housings, carriers or cases are provided with bottomed holes. Insert the ultrasonic sensor (17) (18) (42) (43) (52) (53) into this bottomed hole, and the housing (13) (31) (35) and the outer ring (15a) (16a The ultrasonic sensors (17), (18), (42), (43), (52), and (53) may be exposed to the contact surface with () (41a) (51a). In this case, the bearing load acting on the housing (13) (31) (35) via the outer ring (15a) (16a) (41a) (51a) is the ultrasonic sensor (17) (18) (42) (43) (52) Detected by (53).

FIG. 1 is a schematic diagram showing a first embodiment in which a torque detection device and a pinion shaft support bearing device according to the present invention are applied to a power steering device. FIG. 2 is a longitudinal sectional view showing a rack and pinion mechanism of the power steering apparatus. FIG. 3 is a diagram illustrating an example of an echo waveform obtained by the ultrasonic sensor. FIG. 4 is a graph showing the relationship between the echo ratio obtained by the ultrasonic sensor and the bearing load. FIG. 5 is a schematic diagram showing a second embodiment in which the torque detection device and the pinion shaft support bearing device according to the present invention are applied to a power steering device. FIG. 6 is a diagram for explaining the positional relationship between the housing and the rolling bearing in the power steering apparatus. FIG. 7 is a diagram showing an echo waveform when the rolling bearing is in each positional relationship of FIG. FIG. 8 is a graph showing the relationship between the steering torque and the minimum value of the echo intensity. FIG. 9 is a flowchart for explaining processing means of the second embodiment of the power steering apparatus. FIG. 10 is a longitudinal sectional view showing an embodiment in which the torque detection device and the pinion shaft support bearing device according to the present invention are applied to a power transmission device.

Explanation of symbols

(1) Power steering device
(4) Steering shaft
(6) Torque detection device
(11) Rack housing
(12) Rack shaft
(12a) Rack teeth
(13) Pinion housing (housing)
(14) (32) (36) Pinion shaft (torque detection shaft)
(14a) (33) (38) Pinion
(15) (16) (41) (51) Rolling bearing
(16a) (41a) (51a) Outer ring (fixed ring)
(16c) Ball (rolling element)
(41c) (51c) Roller (rolling element)
(17) (18) (42) (43) (52) (53) Ultrasonic sensor (sensor)
(19) Processing means
(22) Power steering device
(23) Electric motor
(31) Differential carrier (casing)
(35) Differential case (casing)
(40) (50) Pinion shaft support bearing device

Claims (7)

  A torque detection device comprising: a sensor for determining a bearing load acting on a rolling bearing that supports the torque detection shaft; and a processing means for determining a torque acting on the torque detection shaft from the bearing load obtained by the sensor.   2. The torque detection according to claim 1, wherein the sensor is an ultrasonic sensor that detects, as an echo ratio or an echo intensity, a force acting between the rolling element of the rolling bearing and the fixed ring or between the fixed ring and the housing that holds the fixed ring. apparatus. In a pinion shaft support bearing device including a rolling bearing that rotatably supports a pinion shaft having a pinion disposed at one end thereof,
A pinion shaft support bearing device, further comprising: a sensor for obtaining a bearing load acting on the rolling bearing; and a processing means for obtaining a torque acting on the pinion shaft from the bearing load obtained by the sensor.   4. The pinion shaft according to claim 3, wherein the sensor is an ultrasonic sensor that detects, as an echo ratio or an echo intensity, a force acting between a rolling element of a rolling bearing and a fixed ring or between a fixed ring and a housing that holds the fixed ring. Bearing device for support.   A bearing device for supporting a pinion shaft used in a rack and pinion type power steering device, wherein the pinion shaft is connected to the steering shaft without passing through a torsion bar, and the processing means detects the driver's steering from the output of the sensor. The pinion shaft support bearing device according to claim 3 or 4, further comprising a steering assist force calculation unit for obtaining a steering assist force for operation. A rack shaft that is supported so as to be axially movable in a rack housing extending in the left-right direction of the vehicle body, and a pinion shaft that is rotatably supported via at least one rolling bearing inside the pinion housing that intersects the rack housing In a power steering device comprising a torque detection device for obtaining a torque required for steering operation,
The torque detection device according to claim 1 or 2, the steering shaft is connected to the pinion shaft without passing through the torsion bar, and the processing means performs steering for steering operation of the driver from the output of the sensor. A power steering device having a steering assist force calculation unit for obtaining an assist force.   The sensor is an ultrasonic sensor, and the power steering device further includes a motor that moves the rack shaft directly in the axial direction. The processing means detects the minimum value of the echo intensity from the echo waveform output from the ultrasonic sensor. When the detected value is greater than the threshold, the detected value extracting means for extracting the value, the comparing means for comparing whether the detected value is larger or smaller than the threshold, and the motor operation signal is output when the detected value is less than or equal to the threshold. 7. A power steering apparatus according to claim 6, further comprising steering assist mode control means for outputting a motor stop signal.

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