JP2603568B2 - Power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus (power steering apparatus ) mounted on a motor vehicle and assisting a force required for steering operation by a rotating force of an electric motor.

[0002]

2. Description of the Related Art A steering assist motor is driven based on a detection result of a steering torque applied to a steering wheel, and a force required for steering an automobile is assisted by a rotational force of the motor, so that a driver can enjoy a comfortable steering. Electric powered steering devices have been developed that provide the sensation.

Although this power steering apparatus has a slight difference depending on the type of a steering mechanism of an automobile, for example, a pinion connected to a steering wheel shaft (steering column) via a universal joint and meshed with the pinion. In a vehicle comprising a rack shaft and a rack and pinion type steering mechanism for performing steering by converting the rotation of the pinion accompanying the rotation operation of the steering wheel into the movement in the axial direction of the rack shaft, The shaft of the pinion is divided into an input shaft connected to a steering wheel shaft and an output shaft connected to a rack shaft, and these are connected coaxially via a torsion bar, and the input shaft is connected with a torsion generated in the torsion bar. Detecting the steering torque as a relative displacement generated between the output shaft and, for example, while configuring a torque sensor using a potentiometer,
A configuration in which the steering assist motor is arranged to transmit the rotational force of the pinion or another pinion meshing with the rack shaft at a different axial length direction position from the pinion via an appropriate speed reduction device. Has become.

As described above, in the conventional power steering apparatus, the torque sensor and the steering assisting motor are both disposed around the steering mechanism located below the engine room at the front of the vehicle body. Along with being restricted in the arrangement of the motor in an engine room with less surplus space,
In the event of any inconvenience in the torque sensor or the motor, these must be repaired or adjusted in a small space,
There was a drawback in that a difficult maintenance work was forced.

[0005]

Therefore, there has been proposed an arrangement in which the steering shaft is rotated by a motor and a torque sensor is provided on the steering shaft side to solve the above-mentioned difficulties (for example, Japanese Patent Application Laid-Open No. H10-163,873). Showa 60-67264
No. JP-A-61-37581 and JP-A-61-48870) have not yet been put to practical use so that the entire device is large and can be accommodated in the passenger compartment.

Further, for example, dimensional restrictions are strict as in a mini car.
New specifications, it is necessary to shorten the length of the steering shaft in the length direction.
It is necessary. However, if the length dimension of the steering shaft is shortened,
It is difficult to obtain the desired impact energy absorption characteristics
You. In other words, the secondary collision (the driver is
To move and hit the steering wheel)
Above, the shock energy absorption mechanism in the longitudinal direction of the steering shaft
It is preferable to take a large take-up stroke.
Length in the same direction of the part of the structure that does not deform (such as reduction gears)
It is desirable to make it as small as possible. The present invention has been made in view of such a situation .
Absorption of shock energy absorption mechanism in the longitudinal direction of the steering shaft
Stroke can be increased and longer
It is an object of the present invention to provide a power steering device with high reliability over a wide range.

[0007]

In a power steering apparatus according to the present invention, a connecting member is connected to a steering mechanism which is connected to a steering wheel and which is provided inside a vehicle interior and which is provided outside the vehicle interior. A power steering device that drives a steering assist motor based on a detection result of a steering torque applied to the steering wheel, wherein the steering wheel shaft includes a steering wheel-side input shaft and a steering mechanism side.
Output shaft, torsion bar connecting input shaft and output shaft
And torsion displacement of the torsion bar is electrically displaced.
A torque sensor for detecting the steering torque by converting the output to the steering wheel axis the perpendicular to the worm wheel and the worm wheel is fitted to a portion of the steering mechanism side than the disposed position of the torque sensor of the engagement And the rotation of the motor
A transmission having a worm shaft connected to the shaft, and a seal
In front of each of the two spaces separated by bearings with means
Serial are then transmission and receiving said torque sensor, comprising a housing of the steering wheel shaft, the torque of the steering wheel shaft
Seal means on the steering wheel side of the sensor position.
The outer ring of the bearing having the outer ring
It is characterized by being fitted .

In the present invention, a transmission from a motor is provided.
Using worm shaft and worm wheel
As a result, the longitudinal dimension of the portion of the steering shaft that does not deform
You. The transmission and the torque sensor are housed.
The housing is, of course, the former where lubricant is indispensable
And the latter, which requires a clean atmosphere due to its characteristics, as a sensor.
Housed in a space separated by bearings with
High reliability of transmission and torque sensor for a long time
The bearing is secured with this sealing means.
Since these storage spaces are also used for separation and sealing,
The longitudinal dimension of the non-deformed part of the steering wheel shaft can be shortened.
You. Thus, the impact energy at the time of the secondary collision of the steering shaft is
ー The absorption stroke of the absorption mechanism can be extended,
The integrity is improved.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a side sectional view of a shaft system connected to a steering wheel in a power steering apparatus according to the present invention.

The illustrated shaft system has a so-called safety handle structure that absorbs an excessive force in the axial direction when applied to the shaft system and protects the driver in the event of a collision. In the drawing, reference numeral 1 denotes an upper shaft 10 having a steering wheel (not shown) fixed to the upper end (the right end in FIG. 1) coaxial therewith, and a connecting member having a thin cylindrical shape at the lower end.
This is a steering shaft (steering column) that is composed of a lower shaft 12 that is coaxially connected via 11 and that rotates around its axis with the rotation of the steering wheel. In the lower part of the upper shaft 10,
Two annular grooves 10a, 10a are formed at an appropriate distance from each other in the axial direction.
a, a plurality of circular holes penetrating in the radial direction at positions separated in the axial direction by a distance substantially equal to the separation distance between 10a
11a, 11a are formed so as to be substantially equally arranged in the circumferential direction. The upper shaft 10 and the connecting member 11 have circular grooves 10a, 10a formed as circular holes.
After the upper shaft 10 is fitted inside the connecting member 11 until the upper shaft 10 is located inside the formation position of 11a, 11a, resin is injected into the annular grooves 10a, 10a from the respective circular holes 11a, 11a, and the resin is solidified. Connected. The resin is attached to the upper shaft 10 during normal steering operation.
It has sufficient strength against the force acting on the upper shaft 10 and firmly connects the upper shaft 10 and the connecting member 11, but when an excessive force acts on the upper shaft 10 in the axial length direction, it is sheared and broken. Therefore, the upper shaft 10 can move inside the connecting member 11 in the axial direction.

A cylindrical upper shaft housing 20 for supporting the upper shaft 10 therein has a cylindrical connecting member housing 21 surrounding the connecting member 11, and a thin cylindrical sphere holding member 22 provided outside the cylindrical connecting member housing 21. The plurality of small balls 22a, 22a held at two locations in the longitudinal direction are engaged with each other, and as described above, the resin connecting the upper shaft 10 and the connecting member 11 is broken and the upper shaft is broken.
When the 10 moves, each of the small balls 22a, 22a,... Slides on the inner peripheral surface of the upper shaft housing 20 or on the outer peripheral surface of the connecting member housing 21, and the small balls 22a, 22a. The acting impact force is absorbed.

The lower shaft 12 has an upper and lower two input shafts 12a and an output shaft 12b, each of which has a hollow cross-sectional shape. The input shaft 12a has a cylindrical shape and has a cylindrical shape.
Ball bearing inside the lower shaft housing 23 connected to the lower side of
24, and the output shaft 12b is connected to the lower shaft housing 23.
Are supported by ball bearings 25 and 26 fitted inside. These ball bearings 24, 25, 26
Material, and are sealed by ball bearings 25 and 26.
Of worm wheel 50 and worm shaft 51
A space to house the device, where lubricant such as grease
Is enclosed. On the other hand, sealed by ball bearings 25 and 24
In a space that prevents intrusion of fine dust from outside
Represents a torque sensor 4. Lower shaft housing
As shown in FIG. 1 with hatching in the opposite direction, 23 has a two-part configuration including a steering wheel side and a steering mechanism side. Input shaft
Each of the hollow portions of the output shaft 12a and the output shaft 12b has a length substantially equivalent to the sum of the lengths thereof, and a torsion bar 3 formed by processing the central portion into a uniform circular section having a small diameter. Interpolated. The torsion bar 3 has its slightly large-diameter ends locked at the upper end of the input shaft 12a and the lower end of the output shaft 12b by knock pins 3a and 3b penetrating therethrough in the radial direction. The shaft 12a and the output shaft 12b are connected coaxially. At the upper end of the input shaft 12a, the connecting member
The lower end of 11 is externally fitted, is locked together with the torsion bar 3 by the knock pin 3a, and the input shaft 12a rotates with the rotation of the upper shaft 10 via the connecting member 11, in other words, with the rotation of the steering wheel. To rotate. Also the output shaft
The lower end of the universal joint 13b is connected to a steering mechanism (not shown) provided in the engine room at the front of the vehicle body.
The steering is performed in accordance with the direction and amount of rotation of the output shaft 12b.

As described above, since the input shaft 12a and the output shaft 12b are connected via the torsion bar 3, when the steering torque is applied to the steering wheel, the input shaft that rotates together with the steering wheel.
A relative displacement is generated between the output shaft 12a and the output shaft 12b connected to the pinion shaft in a restrained state in the steering mechanism, according to the torsion generated in the torsion bar 3 by the steering torque. The torque sensor 4 mounted between the input shaft 12a and the output shaft 12b uses a potentiometer that detects a steering torque as the relative displacement, and is attached to a sleeve 40 loosely fitted to the input shaft 12a. A resistor holding member 41 fitted with the sleeve 40 and the rotation thereof being restricted by the input shaft 12a by a pin 41a together with the sleeve 40, and the upper half thereof is
40, the lower half thereof is loosely fitted to the upper end of the output shaft 12b, and its rotation is performed by the pin 42a.
And a detector holding member 42 constrained by 2b. The lower end surface of the resistor holding member 41 and the upper end surface of the detector holding member 42 are respectively orthogonal to the axis of the lower shaft 12 and are opposed to each other with an appropriate distance in the axial direction. A resistor 43 of a potentiometer is formed in an appropriate ring around the axis thereof, and a detector 44 which is in sliding contact with the resistor 43 is mounted on the latter. Application of predetermined potential to resistor 43 and detector
Extraction of the output potential of the potentiometer having a value corresponding to the sliding contact position of 44 is performed by slip ring wires 46, 45 sliding separately on a plurality of slip rings 45, 45 provided on the outer peripheral surface of the resistor holding member 41. 46 and a terminal box 47 fixed to the lower shaft housing 23. FIG. 2 shows the torque sensor 4
FIG. 4 is an enlarged sectional view of a portion of FIG.
As shown in the figure, through capacitors 49, 49, each having one side connected to the body ground, are interposed between the 6, 46 ... and the lead wires 48, 48 ... respectively connected to these. This prevents a disturbance potential due to an external electromagnetic interference from being added to the potential applied to the potentiometer or the output potential of the potentiometer. In order to obtain a further prevention effect, a shield wire may be used for the lead wires 48, 48. Further, the feedthrough condensers 49, 49, which are interposed as described above, are provided with slip ring wires 46, 46,.
Through the lower shaft housing 23
Dust and the like are also prevented from entering, and there is no risk of malfunction of the torque sensor 4 due to these.

The output signal of the torque sensor 4 is given to the input side of the control unit 7, and the control unit 7 recognizes the direction and magnitude of the steering torque applied to the steering wheel based on this signal, and The steering assist motor 5 (see FIG. 3) connected to the output side of the motor 7 via a drive circuit (not shown) is rotated in a direction corresponding to the operation direction of the steering wheel.

A worm wheel 50 for transmitting the rotational force of the steering assist motor 5 to the output shaft 12b is fitted coaxially with the output shaft 12b at an intermediate portion in the axial direction of the output shaft 12b. Have been. The worm wheel 50 has an output shaft 1
The inner ring of the ball bearing 25 supporting the upper part of the output shaft 2b and the output shaft 12b
Both sides are sandwiched by the inner ring of the ball bearing 26, which is press-fitted and fixed to the outer peripheral surface of the lower part of the output shaft 12b and supports the lower part of the output shaft 12b, and is positioned in the axial direction. I have. These ball bearings 25 and 26 are 2
The part of the lower shaft housing 23 of the split configuration on the steering mechanism side is
The outer ring of the ball bearing 25 is fitted in the lower shaft housing.
Ring 23 between the two parts. Worm wheel
A worm shaft 51 interlocked with the motor 5 for assisting steering is meshed with the outer peripheral surface of the motor 50 so that its axis is perpendicular to the shaft.

FIG. 3 is a sectional view taken along line III-III of FIG. 1 showing the structure of the transmission mechanism of the motor 5. As shown in FIG. As shown in the figure, the worm shaft 51 has a worm tooth formed at an intermediate portion in the axial direction thereof, and a lower end of the worm shaft 51 having a diameter equal to or smaller than the root diameter of the worm tooth is a lower shaft. The ball bearing 52, which is press-fitted and fixed to the housing 23, is internally fitted and supported by this,
Also, the base part side middle part is supported by a ball bearing 53 located on the opposite side to the ball bearing 52 with the worm tooth forming part sandwiched therebetween, and as described above, the lower part with the worm wheel 50 and the shaft center orthogonal to each other. The shaft is supported inside the shaft housing 23. The ball bearing 53 includes a large-diameter portion provided on both sides of an inner ring of the worm shaft 51 at an intermediate portion of the worm shaft 51 in a state of being fitted to the worm shaft 51 and a retaining ring 51a engaged with an outer peripheral surface of the shaft 51. After that, the outer ring of the worm shaft 51 and the worm shaft 51 are fitted in bearing mounting holes formed in the lower shaft housing 23, and both sides of the outer ring are engaged with the inner peripheral surface of the mounting hole. The retaining ring 51b and the bottom surface of the mounting hole are sandwiched and positioned in the axial direction to support the worm shaft 51 in the radial and thrust directions. The motor 5 for assisting steering is fitted into a motor mounting hole formed in the lower shaft housing 23 with the electromagnetic clutch 6 coaxially and coaxially connected to the rotation shaft thereof as an inner side, and is fixed with mounting bolts to fix the worm shaft 51. Lower shaft housing to be coaxial with
It is attached to the outside of 23. The worm shaft 51 is engaged with the output shaft of the electromagnetic clutch 6 by a spline 51c formed at the end on the ball bearing 53 side, and the rotational force of the motor 5 is transmitted to the worm shaft 51 via the electromagnetic clutch 6. Communicated,
Further, the power is transmitted to the output shaft 12b via a worm wheel 50 that meshes with the shaft 51.

Since the transmission mechanism of the motor 5 has such a structure and the electromagnetic clutch 6 and the worm shaft 51 are spline-coupled, the motor 5 can be easily moved together with the electromagnetic clutch 6 simply by removing its mounting bolt. Also, since the tip of the worm shaft 51 is smaller in diameter than the root diameter of the worm teeth, the worm shaft 53 is pulled forward by removing the retaining ring 51b and pulling the worm shaft 53 forward. It can be easily taken out together with the bearing 53. Therefore, the transmission mechanism can be easily inspected or repaired, and the worm wheel 50 and the worm shaft 51 can be used during initial assembly.
If the consistency between the two is poor, the worm shaft 51 is taken out as described above and replaced with another worm shaft 51, whereby the consistency between the two can be easily improved.

The supply and disconnection of the drive current to the motor 5 is performed by the operation of the control unit 7 in accordance with the magnitude and direction of the steering torque detected by the torque sensor 4. The torque of the motor 5 rotated by the drive current is transmitted to the output shaft 12b via the electromagnetic clutch 6, the worm shaft 51 and the worm wheel 50 as described above, and further transmitted through the universal joint 13 to the pinion in the steering mechanism. The rack shaft is transmitted to the shaft, and the rack shaft is moved leftward or rightward as the pinion shaft rotates, thereby steering leftward or rightward.

FIG. 4 is a schematic sectional view showing a brush mounting structure inside the motor 5. As shown in FIG. The brush 54 is housed inside a box-shaped brush mount 55 in a state where its tip is slidably contacted with the outer peripheral surface of the commutator 56 of the motor 5 in the radial direction. It is attached in a state where it is urged in a direction toward the commutator 56 by a spiral spring 57 that is locked by the spring. The spiral spring 57 has one end locked by a locking member 58 provided at an appropriate position, and the other end inserted into a hole 54a formed at the base of the brush 54, and is attached to the brush 54 in the above-described direction. An urging force is applied to surely bring the brush 54 into sliding contact with the commutator 56 even when the abrasion of the brush 54 progresses, but after the abrasion of the brush 54 reaches a predetermined amount, the urging force Stopper 59 to prevent the addition of
The spiral spring 57 is provided so as to be in contact with the middle part on the other end side. The stopper 59 advances until the wear of the brush 54 reaches the position of the hole 54a, and the end of the spiral spring 57 inserted into the hole 54a contacts the commutator 56 to
Are provided to prevent the rotor from being restrained. When the rotor of the motor 5 is restrained, the rotation of the output shaft 12b is restrained via the worm shaft 51 connected to the motor 5 and the worm wheel 50 meshing with the worm shaft 51. As a result, steering may not be possible. However, when the stopper 59 is provided as described above, the contact state between the brush 54 and the commutator 56 is not maintained properly after the spiral spring 57 contacts the stopper 59, and as a result, the drive current to the motor 5 is reduced. Although the supply is stopped, the rotation of the output shaft 12b is not restricted because the rotor of the motor 5 is not restricted, and the danger of being unable to steer is avoided.

[0020]

As described above in detail, in the power steering apparatus according to the present invention, the worm is used as the transmission from the motor.
Since the shaft and worm wheel are used, the steering shaft
The length in the longitudinal direction of the unshaped portion is reduced. Also this transmission
The housing housing the device and the torque sensor
Needless to say, the former, for which lubricant is indispensable, and the nature of a sensor
Shaft having sealing means for the latter requiring a clean atmosphere
Since it is stored in the space separated by the receiver, the transmission device and
Long-term high reliability of the torque sensor is ensured, and
These storage spaces are separated and sealed by bearings.
Therefore, the longitudinal dimension of the portion of the steering wheel shaft that does not deform
Can be shortened. Due to these, the impact at the time of secondary collision of the steering wheel shaft
It is possible to lengthen the absorption stroke of the energy absorption mechanism
Yes, safety is improved.

Further, as shown in the embodiment, the meshing position between the worm shaft and the worm wheel can be appropriately set on the periphery of the worm wheel. It can be mounted at any position in the direction, and it can be placed in the extra space inside the cabin. Furthermore, since the power steering device according to the present invention can be configured compactly below the steering wheel shaft, it can be applied to an automobile having a safety handle structure as shown in the embodiment. Since it can be retrofitted simply by replacing it with the housing, it has an excellent effect such as being able to easily convert a manually-steered vehicle into a vehicle equipped with a power steering device.

[Brief description of the drawings]

FIG. 1 is a sectional view of a power steering device according to the present invention.

FIG. 2 is an enlarged sectional view of a torque sensor unit.

FIG. 3 shows a configuration of a transmission mechanism of the motor.
It is an expanded sectional view by the I line.

FIG. 4 is a schematic diagram showing a brush mounting structure inside a motor.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 steering wheel shaft 3 torsion bar 4 torque sensor 5 motor 6 electromagnetic clutch 10 upper shaft 11 connecting member 12 lower shaft 12a input shaft 12b output shaft 23 lower shaft housing 25,26 ball bearing 50 worm wheel 51 worm shaft 52,53 ball bearing

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Hideo Matsubara 3-5-8 Minamisenba, Chuo-ku, Osaka-shi, Osaka Inside of Koyo Seiko Co., Ltd. (72) Miichi Ikegi 3-chome, Minamisenba, Chuo-ku, Osaka-shi, Osaka No. 5-8 Koyo Seiko Co., Ltd. (72) Inventor Masayuki Watanabe 3-58 Minamisenba, Chuo-ku, Osaka City, Osaka Prefecture No. 5-8, Koyo Seiko Co., Ltd. (56) References JP-A-60-234069 (JP, A) JP-A-61-241270 (JP, A) JP-A-61-37581 (JP, A) Showa 61-58169 (JP, U) Actually open Showa 58-49075 (JP, U)

Claims (1)

(57) [Claims] A steering shaft connected to the steering wheel and disposed inside the vehicle interior via a connecting member to a steering mechanism disposed outside the vehicle interior, and a steering torque applied to the steering wheel; In the power steering apparatus for driving a steering assist motor based on the detection result, the steering shaft is an input shaft on the steering wheel side and an output shaft on the steering mechanism side.
And a torsion bar connecting the input shaft and the output shaft.
The torsion bar converts the torsion displacement into an electrical displacement and outputs it.
Wherein a torque sensor for detecting steering torque, the steering wheel axis the perpendicular to the worm wheel and the worm wheel is fitted to a portion of the steering mechanism side than the disposed position of the torque sensor is engaged Te, the motor On the axis of rotation
A transmission having a worm shaft to be connected thereto and two spaces separated by a bearing having a sealing means
And a housing for the steering wheel shaft, each housing the transmission device and the torque sensor , wherein the steering wheel is located closer to the steering wheel than the torque sensor is disposed on the steering wheel shaft.
The inner ring of the bearing having the sealing means is
A power steering device characterized by being fitted inside the housing .