JP2004136827A - Steering device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce transmission sound accompanying transmission from a motor driven according to steering to a steering shaft in a steering mechanism without increasing an arranging space including the motor. <P>SOLUTION: The motor 3 is attached outside of a rack housing H<SB>1</SB>in parallel thereto, and a rotating disk 40 is fitted to an output shaft 31 of the motor 3. A driving gear 7 is meshed with a driven gear 6 peripherally provided on an external surface of a ball nut 5 screwed in a screw groove 50 provided in the outer periphery in the intermediate part of a rack shaft 1. The rotating disk 41 is fitted to a gear shaft 70 of the driving gear 7. Eccentric pins 42, 43 projected in one side of the rotating disks 40, 41 are connected with a crank connecting rod 44 to constitute a crank mechanism 4, the rotation of the motor 3 is transmitted to the driving gear 7 by operation of the crank mechanism 4, and transmitted to the ball nut 5 through the driven gear 6 directly meshed with the drive gear 7 to slide the rack shaft 1 in a shaft longitudinal direction. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vehicle steering system including a motor that is driven in accordance with an operation of a steering member such as a steering wheel so as to apply a moving force in an axial direction for steering to a steering shaft in a steering mechanism.
[0002]
[Prior art]
The steering of the vehicle is performed by operating a steering member (generally, rotating a steering wheel) performed by a driver in the interior of the vehicle compartment, and turning the steering wheel (generally, a front wheel) in the vehicle compartment to steer the steering wheel (generally, the front wheel). This is carried out by transmitting it to an externally arranged steering mechanism.
[0003]
As a steering device for performing such steering, in recent years, a torque of a motor that is rotationally driven based on a detection result of a steering torque applied to a steering member is transmitted to a steering mechanism, and the torque of the motor described above is used. A steering device (electric power steering device) configured to assist the steering is widely used, and a steering device configured to perform steering only by the rotational force of the motor, a so-called steer-by-wire steering device is also used. Some have been put to practical use.
[0004]
This type of steering device converts, for example, the rotational motion of the motor into a linear motion and transmits the linear motion to a steering shaft in a steering mechanism, and transmits the axial movement of the steering shaft to left and right steering wheels to perform steering. In particular, a screw mechanism (ball screw mechanism) including a screw groove formed on the peripheral surface of the steering shaft and a nut member screwed into the screw groove is provided as a motion conversion means. A configuration is widely used in which the rotation of the motor is transmitted to a nut member (ball nut) and the steering shaft is moved by using the screw advance of a thread groove according to the rotation of the nut member (for example, Patent Document 1). 1, 2, 3). The steering shaft is, for example, a rack shaft in a rack and pinion type steering device.
[0005]
[Patent Document 1]
Japanese Utility Model Registration No. 2590791 [Patent Document 2]
Japanese Patent Publication No. 3-15591 [Patent Document 3]
JP-A-8-207796
[Problems to be solved by the invention]
The steering devices disclosed in Patent Documents 1, 2, and 3 differ from each other in the configuration of a transmission system that transmits the rotation of the motor to a nut member. In Patent Document 1, a rack shaft as a steering shaft is used. A motor is disposed outside the supporting housing so as to be substantially parallel to the rack shaft, and the rotation of a drive gear attached to the output end of the motor is integrally formed on the outer periphery of the ball nut via an intermediate gear. The transmission is performed to the driven gear.
[0007]
However, in this configuration, there is a disadvantage that a gear rattling sound is generated between the driving gear and the driven gear and the intermediate gear due to the transmission, and the transmission noise is large, and in order to solve this difficulty, the backlash adjusting means of each gear is provided. When attached, there is a problem that the configuration of the transmission system becomes complicated.
[0008]
Further, in Patent Document 2, a motor is disposed outside a housing that supports a rack shaft as a steering shaft so as to be substantially parallel to the rack shaft, and a drive gear attached to an output end of the motor is a ball nut. It is configured to mesh with a large-diameter driven gear provided on the outer periphery and directly transmit the rotation of the motor to the ball nut. Further, in Patent Document 3, a motor is arranged outside a housing supporting a rack shaft as a steering shaft so as to be inclined with respect to the rack shaft, and attached to an output end of the motor projecting into the housing. The bevel gear (drive gear) meshes with a bevel gear (driven gear) provided on the outer periphery of the ball nut, and the rotation of the motor is directly transmitted to the ball nut.
[0009]
According to these configurations, since no intermediate gear is provided, the backlash between the drive gear and the driven gear can be easily optimized by, for example, adjusting the mounting position of the motor, and the transmission noise can be reduced. Can be achieved. However, in the configuration of Patent Document 2, the housing has a large diameter at the storage position of the large-diameter driven gear. Therefore, there is a problem that it is difficult to dispose it in a limited space around the steering mechanism.
[0010]
The present invention has been made in view of the above circumstances, and it is possible to reduce transmission noise accompanying transmission from a motor driven in accordance with steering to a steering shaft in a steering mechanism. It is an object of the present invention to provide a vehicle steering system provided with a transmission means that can be easily arranged including a motor in a limited space around the vehicle.
[0011]
[Means for Solving the Problems]
A vehicle steering apparatus according to a first aspect of the present invention transmits a torque of a motor driven in accordance with an operation of a steering member to a steering shaft in a steering mechanism, and moves the steering shaft in an axial direction. In a vehicle steering device for performing steering, a cylindrical nut member externally fitted to the steering shaft and screwed into a screw groove provided on a peripheral surface of the steering shaft, and provided around the outer surface of the nut member. A driven gear, a drive gear meshed with the driven gear and rotated about an axis substantially parallel to the steering shaft, and a crank mechanism for transmitting rotation of the motor to the drive gear.
[0012]
In the present invention, a driven gear rotating around an axis parallel to the driven gear is meshed with a driven gear provided on the outer surface of a nut member (ball nut) screwed into a thread groove on the peripheral surface of the steering shaft, The drive gear and an output shaft of a motor driven in accordance with steering are connected by a crank mechanism, the rotation of the motor is transmitted to the drive gear via the crank mechanism, and the rotation of the drive gear is provided with a driven gear. The steering is transmitted to the member and the steering shaft is moved by using the screw advance of the thread groove according to the rotation of the nut member, thereby performing the steering. The motor connected to the drive gear via the crank mechanism can be disposed substantially parallel to the drive gear, the nut member and the steering shaft, and does not require a large installation space outside the housing of the steering shaft. . Also, only the drive gear meshes with the driven gear of the nut member, and transmission noise can be reduced by optimizing the backlash between the two gears.
[0013]
Further, in the vehicle steering apparatus according to the second invention, the crank mechanism according to the first invention is configured such that the eccentric pin protrudingly provided on one side of a rotating disk that rotates integrally with the output shaft of the motor, the driving gear or the driving gear. The eccentric pin is provided with an eccentric pin protruding from one side surface of a rotating disk that rotates integrally, and a crank rod having both ends connected to the eccentric pin.
[0014]
In the present invention, an eccentric pin is protruded from one surface of a rotating disk that rotates integrally with a motor output shaft and a driving gear, respectively, and these are connected by a crank rod to transmit the rotation of the motor to the driving gear. The mechanism is simply configured. The rotating disk on the driving gear side may also serve as the driving gear itself.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic diagram showing the overall configuration of a vehicle steering system according to the present invention. The vehicle steering system shown in the figure transmits a torque of a steering assisting motor 3 to a rack shaft 1 as a steering shaft, and moves the rack shaft 1 in the axial direction to assist the steering. It is configured as an electric power steering device.
[0016]
The rack shaft 1 is movably supported in the axial direction inside the rack housing H ₁ having a cylindrical shape, and extends in the lateral direction of the vehicle body, not shown. Both ends of the rack shaft 1 that protrude on both sides of the rack housing H ₁ is connected via a knuckle respective tie rods 12, 12 to the arms 11, 11 of the left and right front wheels 10, 10 as a steering wheel, a rack By moving the shaft 1 in both directions, the knuckle arms 11, 11 are pushed and pulled via the tie rods 12, 12, and the left and right front wheels 10, 10 are steered.
[0017]
In the vicinity one end of the rack housing H _1, to cross it and the shaft center and the pinion housing H ₂ is continuously provided, the inside of the pinion housing H _2, rotatably pinion in the axis around A shaft 2 is supported. The pinion shaft 2, only the protruding end of the upper pinion housing H ₂ is Yes illustrated, the protruding end is connected to a steering wheel 21 as a steering member via a column shaft 20.
[0018]
At the bottom of the pinion shaft 2 that extends inside the pinion housing H _2, a pinion (not shown) is provided integrally. Further, the rack shaft 1 supported in the rack housing H _1, and the rack teeth are formed over a suitable length, including the intersecting position between the pinion housing H _2, the rack teeth, the pinion shaft 2 lower Of the pinion.
[0019]
With the above configuration, when the steering wheel 21 is rotated for steering, the pinion shaft 2 connected to the steering wheel 21 via the column shaft 20 rotates, and this rotation is performed by the pinion and the rack teeth. In the meshing portion, the movement is converted into the movement of the rack shaft 1 in the axial length direction. By this movement, the left and right front wheels 10, 10 are steered as described above, and the steering according to the operation of the steering wheel 21 is performed.
[0020]
Such motor 3 for steering assistance for assisting the steering, an intermediate portion motor bracket 30 projecting from the outside of the rack housing H _1, is attached so as to form the interior of the rack shaft 1 substantially parallel, motor is transmission configured to the rack shaft 1 by the configured transmission means as described below in the communicating portion of the bracket 30 and the rack housing H _1.
[0021]
FIG. 2 is a longitudinal sectional view showing a configuration of a transmission means from the steering assisting motor 3 to the rack shaft 1. Motor bracket 30 which the motor 3 is attached is in communication with the interior of the rack housing H ₁ as shown, the distal end of the output shaft 31 of the motor 3 which projects into the interior of the motor bracket 30, the rotary disc 40 It is fitted and fixed coaxially.
[0022]
The inside of the rack housing H _1, the ball nut 5 having a cylindrical shape, rotatable on the rack shaft 1 coaxially by a pair of ball bearings 51 and 51 which are fitted on either side of the communication portion of the motor bracket 30 It is supported by. On the outer peripheral surface of the rack shaft 1, a screw groove 50 having a semicircular cross section is formed over an appropriate length including the inside of the ball nut 5, and formed on the screw groove 50 and the inner surface of the ball nut 5. A ball screw mechanism is formed by screwing a similar screw groove through a number of balls.
[0023]
A driven gear 6 is integrally formed on the outer peripheral surface of the ball nut 5 between support portions of the ball bearings 51, 51, and the driven gear 6 is substantially parallel to the rack shaft 1 in a communication portion with the motor bracket 30. And is meshed with the driving gear 7 supported. A rotating disk 41 is integrally formed at the tip of the rotating shaft 70 of the drive gear 7 so as to correspond to the rotating disk 40 fitted to the output shaft 31 of the motor 3.
[0024]
FIG. 3 is a cross-sectional view showing a connection state of the rotating disks 40 and 41. As shown in the figure, eccentric pins 42, 43 project from one surface of the rotating disks 40, 41 at positions substantially equidistant from their respective axes, and these eccentric pins 42, 43 are connected to crank rods. The crank mechanism 4 is connected by 44 and transmits the rotation of one rotating disk 40 by the transmission from the motor 3 to the other rotating disk 41 and the driving gear 7.
[0025]
When the motor 3 is rotationally driven by the above configuration, this rotation is transmitted to the rotating disk 40 via the output shaft 31. When the rotating disk 40 is rotated, an eccentric pin 42 projecting from one surface of the rotating disk 40 is displaced on the eccentric circumference, and this displacement is projected on one surface of the other rotating disk 41 via the crank rod 44. The eccentric pin 43 is displaced on the eccentric circumference, and the rotating disk 41 rotates with this displacement, and this rotation is transmitted to the drive gear 7.
[0026]
The drive gear 7 meshes with a driven gear 6 on the outer periphery of the ball nut 5, and rotation of the drive gear 7 is transmitted to the ball nut 5 via the driven gear 6, and the ball nut 5 rotates around an axis. Due to this rotation, the screw groove 50 screwed into the screw groove on the inner periphery of the ball nut 5 via a number of balls advances, and a moving force in the axial direction is applied to the rack shaft 1 on which the screw groove 50 is formed. In accordance with this movement, the steering performed as described above is assisted.
[0027]
At this time, the moving force (steering assist force) applied to the rack shaft 1 is changed by drive control of the steering assist motor 3. As is well known, the drive control of the motor 3 is performed by controlling the control value determined based on the detection result of the steering torque applied to the column shaft 20 in response to the operation of the steering wheel 21 to the running state such as the vehicle speed, the yaw rate, and the lateral acceleration. This is realized by a procedure for correcting based on the detection result. As a result, a steering assist force according to the steering situation is applied to the rack shaft 1, and the driver operating the steering wheel 21 can experience a good steering feeling.
[0028]
In the vehicle steering system according to the present invention, the two gears (the driving gear 7 and the driven gear 6) that mesh with each other in the transmission system from the steering assist motor 3 to the ball nut 5 that is driven and controlled as described above. The backlash in these meshing portions can be easily adjusted by adjusting the positions of both gears during the assembling stage, thereby suppressing generation of rattle noise and reducing transmission noise. it can.
[0029]
The transmission from the motor 3 to the drive gear 7 is performed via a crank mechanism 4 which can surely transmit the rotational force between distant positions. As a result, as shown in FIG. ₁ can be arranged in parallel outside. Further, the drive gear 7 can be disposed close to the ball nut 5, and meshes with the drive gear 7. The driven gear 6, which is provided around the ball nut 5 and a smaller diameter, need a large diameter eliminates the corresponding sites of the rack housing H _1. Therefore, even when the installation space around the steering mechanism is limited, it is possible to dispose without hindrance the rack housing H _1, including the motor 3.
[0030]
In the above embodiment, the rotating disk 40 fitted to the output shaft 31 of the motor 3 and the rotating disk 41 fitted to the rotating shaft 70 of the drive gear 7 are connected by the crank rod 44. Although the crank mechanism 4 is configured, the crank mechanism may be configured by attaching a crank arm to each of the output shaft 31 and the drive shaft 70 and connecting these by a crank rod. The rotating disk 41 on the driving gear 7 side can also serve as the driving gear 7 itself, and an eccentric pin 43 is protruded from one surface of the driving gear 7, and the eccentric pin 43 and the rotating disk on the motor 3 side are provided. It is also possible to configure the crank mechanism 4 by connecting the eccentric pin 42 protrudingly provided at 40 with a crank rod 44.
[0031]
Further, in the above embodiment, the example of application to the rack and pinion type electric power steering device including the rack shaft 1 as the steering shaft has been described. However, the present invention relates to a steering system that moves in the axial direction for steering. It is needless to say that the present invention can be applied to any type of electric power steering apparatus having a shaft and assisting the movement of the steering shaft by the generated force of a motor.
[0032]
In the above embodiment, the ball screw mechanism provided with the ball nut 5 is used to convert the rotation of the motor 3 into the axial movement of the rack shaft 1 as the steering shaft. Other screw mechanisms may be used.
[0033]
Further, the present invention provides a steering device, which is provided with a steering member mechanically separated from the steering mechanism, and performs steering only by the rotational force of a motor driven in accordance with the operation of the steering member. Application to a by-wire type steering device is also possible.
[0034]
【The invention's effect】
As described in detail above, in the vehicle steering system according to the present invention, since the transmission system for transmitting the rotation of the motor driven in accordance with the steering to the steering shaft is provided with the crank mechanism, the motor is parallel to the steering shaft. Direct transmission from the drive gear to the driven gear is possible while arranging the gears, realizing both the reduction of transmission noise by optimizing the backlash and the arrangement including the motor in a limited space. can do.
[0035]
In addition, a crank mechanism is formed by connecting eccentric pins projecting from one surface of a rotating disk that rotates integrally with the output shaft and the drive gear of the motor by a crank rod, so that a reliable transmission is achieved by a simple configuration. The present invention has an excellent effect, for example, it is possible to make it possible.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an overall configuration of a vehicle steering device according to the present invention.
FIG. 2 is a longitudinal sectional view showing a configuration of a transmission means from a steering assist motor to a rack shaft.
FIG. 3 is a cross-sectional view showing a connection state of a rotating disk.
[Explanation of symbols]
1 Rack axis (steering axis)
2 Pinion shaft 3 Motor 4 Crank mechanism 5 Ball nut (nut member)
6 Drive gear 7 Drive gear 31 Output shaft 40, 41 Rotating disk 42, 43 Eccentric pin 44 Crank rod 50 Screw groove H ₁ Rack housing H ₂ Pinion housing

Claims (2)

In a vehicle steering apparatus for transmitting a rotational force of a motor driven in accordance with an operation of a steering member to a steering shaft in a steering mechanism and performing steering by moving the steering shaft in an axial direction,
A cylindrical nut member externally fitted to the steering shaft and screwed into a screw groove provided on a peripheral surface of the steering shaft;
A driven gear provided on the outer surface of the nut member;
A driving gear meshed with the driven gear and rotated about an axis substantially parallel to the steering shaft;
A steering mechanism for transmitting a rotation of the motor to the drive gear. The crank mechanism has an eccentric pin protruding from one side of a rotating disk that rotates integrally with the output shaft of the motor, and an eccentric pin protruding from one side of the driving gear or the rotating disk that rotates integrally with the driving gear. The vehicle steering system according to claim 1, further comprising a pin, and a crank rod having both ends connected to the eccentric pins.

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