JP5828559B2 - Electric power steering device - Google Patents

Description

  The present invention relates to an electric power steering apparatus.

  As a conventional electric power steering apparatus, FIG. 1 of Patent Document 1 discloses an apparatus in which a coil spring for supporting a steering apparatus body with respect to a vehicle body is attached to a fixed bracket.

JP 2002-255044 A

  The electric power steering device described in Patent Document 1 requires a mounting seat for mounting a coil spring to the fixed bracket, and thus the structure is complicated.

  Further, since the coil spring is provided across the fixing bracket and the steering device main body, there is a possibility of interference with other parts, and the layout of the other parts is limited.

  The present invention has been made in view of the above problems, and an object thereof is to simplify the structure of an electric power steering apparatus and to improve the degree of freedom of layout of other components.

The present invention is an electric power steering device that assists a steering force applied to a steering wheel by a driver with the rotational torque of an electric motor, and supports a steering shaft to which the steering wheel is coupled and the steering shaft rotatably. A steering column, a fixed bracket that is fixed to the vehicle body and supports the steering column via a support shaft, a gear case that houses a worm wheel that transmits the rotational torque of the electric motor, and the steering wheel that extends in the vertical direction A tilt mechanism that allows the steering column to swing about the support shaft so as to move; a release mechanism that can switch between swing control of the steering column and release of the control; and an outer periphery of the support shaft Provided by the release mechanism. When regulation of the swinging ring column is released, includes a spring for applying a biasing force against the weight of the electric power steering device, the said spring, said end portions and each of the fixed bracket gear case A torsion spring that is always in contact and generates a torsional reaction force between the fixed bracket and the gear case when the restriction of the swing of the steering column is released by the release mechanism; and the spring Functions as a ground path for the electrical system around the steering wheel .

  According to the present invention, since the spring is provided on the outer periphery of the support shaft, which is the swing center of the steering column when adjusting the tilt of the steering wheel, there is no interference with other parts, and the mounting seat for mounting the spring Is no longer necessary. Therefore, the structure of the electric power steering device can be simplified, and the degree of freedom in layout of other components can be improved.

1 is a plan view of an electric power steering device according to an embodiment of the present invention. 1 is a side view of an electric power steering apparatus according to an embodiment of the present invention. 1 is a cross-sectional view of an electric power steering device according to an embodiment of the present invention. It is a perspective view of the gear case periphery of the electric power steering apparatus which concerns on embodiment of this invention, and illustration of the output shaft is abbreviate | omitted. It is a perspective view of the gear case periphery of the electric power steering apparatus which concerns on embodiment of this invention, and illustration of the output shaft is abbreviate | omitted. It is a perspective view of a torsion spring.

  An electric power steering apparatus 100 according to an embodiment of the present invention will be described with reference to the drawings.

  First, the overall configuration of the electric power steering apparatus 100 will be described with reference to FIGS.

  The electric power steering device 100 is a device that assists the steering force applied by the driver to the steering wheel 8 with the rotational torque of the electric motor 13.

  The electric power steering apparatus 100 is connected to the steering shaft 1 via a steering shaft 1 to which a steering wheel 8 is connected, a steering column 2 that rotatably supports the steering shaft 1 inserted inside, and a torsion bar 3. An output shaft 4.

  The output shaft 4 is connected to the wheels via universal joints 5 and 6, an intermediate shaft 7, a pinion, a rack, and the like. As the driver steers the steering wheel 8, the rack moves in the axial direction and the direction of the wheels changes. In the following description, it is assumed that the steering wheel 8 side is the upper side and the wheel side is the lower side.

  The electric power steering apparatus 100 includes an assist mechanism that assists the steering force applied by the driver to the steering wheel 8. The assist mechanism detects a worm wheel 9 connected to the output shaft 4, a worm shaft 10 that meshes with the worm wheel 9, an electric motor 13 that rotationally drives the worm shaft 10, and a steering torque that acts on the torsion bar 3. A torque sensor 14 and a controller that controls the driving of the electric motor 13 based on the detection result of the torque sensor 14 are provided. The rotational torque output from the electric motor 13 is transmitted from the worm shaft 10 to the worm wheel 9 and applied to the output shaft 4 as auxiliary torque. The rotational torque output from the electric motor 13 is calculated based on the steering torque detected by the torque sensor 14.

  The torque sensor 14 is accommodated in the sensor case 31, and the worm wheel 9 and the worm shaft 10 are accommodated in the gear case 32. The sensor case 31 and the gear case 32 are fastened by bolts 39.

  The steering shaft 1 has a substantially cylindrical upper shaft 11 to which a steering wheel 8 is coupled to an upper end portion 11a, a substantially cylindrical lower shaft that is coaxially connected to the upper shaft 11 and to which a torsion bar 3 is coupled to a lower end portion. A shaft 12. The upper side of the lower shaft 12 is inserted into the hollow portion of the upper shaft 11, and both are serrated. The upper shaft 11 and the lower shaft 12 can be integrally rotated and relatively moved in the axial direction by serration coupling. A bearing 24 is interposed between the lower side of the lower shaft 12 and the inner peripheral surface of the sensor case 31.

  The steering column 2 is disposed substantially coaxially with the upper column tube 21 that rotatably supports the upper shaft 11 via a bearing 23 and the upper column tube 21, and a lower end portion is fixed to the sensor case 31. And a substantially cylindrical lower column tube 22. The upper side of the lower column tube 22 is inserted into the lower side of the upper column tube 21, and both are relatively movable in the axial direction. The relative movement in the axial direction of the upper shaft 11 and the upper column tube 21 is restricted by a bearing 23. A cylindrical small diameter portion 31a having a smaller diameter than other portions is formed at the upper end portion of the sensor case 31, and the inner peripheral surface of the lower end portion of the lower column tube 22 is press-fitted into the outer peripheral surface of the small diameter portion 31a.

  The output shaft 4 is rotatably supported by the sensor case 31 and the gear case 32 via bearings 15 and 16, respectively. The output shaft 4 has a cylindrical shape, and the torsion bar 3 is inserted into the hollow portion.

  The upper end portion of the torsion bar 3 protrudes from the upper end opening portion of the output shaft 4 and is press-fitted and connected to the lower end portion of the lower shaft 12. A lower end portion of the torsion bar 3 is connected to a lower end portion of the output shaft 4 via a pin 28. The lower shaft 12 and the output shaft 4 are connected coaxially via the torsion bar 3. The torsion bar 3 transmits the steering torque input to the steering shaft 1 via the steering wheel 8 to the output shaft 4 and is torsionally deformed about the axis according to the steering torque.

  The torque sensor 14 includes a magnetic sensor 41 that detects a magnetic flux density that changes with the magnitude of torsional deformation of the torsion bar 3, and detects a steering torque that acts on the torsion bar 3 based on the output of the magnetic sensor 41. .

  The electric power steering apparatus 100 is attached to the vehicle body via an upper fixing bracket 33 and a lower fixing bracket 34 fixed to the vehicle body. The lower fixing bracket 34 is shown as a component of the electric power steering apparatus 100 in FIGS. 1 and 2, but the electric power steering apparatus 100 is attached to the lower fixing bracket 34 fixed to the vehicle body. Also good.

  Next, the periphery of the lower fixing bracket 34 will be described mainly with reference to FIGS. 4 and 5. 4 and 5 are perspective views of the periphery of the gear case 32 of the electric power steering apparatus 100, and the output shaft 4 is not shown. 4 and 5 are views of the electric power steering apparatus 100 as seen from another direction.

  The lower fixing bracket 34 is a box-shaped member, and is fixed to the vehicle body via a mounting seat 34a. The lower fixing bracket 34 is provided with a pivot pin 35 that penetrates both side walls 34b. The pivot pin 35 is fixed to the lower fixing bracket 34 by sandwiching both side walls 34b of the lower fixing bracket 34 by a head 36a and a nut 36 screwed to the tip. The pivot pin 35 is inserted through a cylindrical sleeve 37 disposed between both side walls 34b. The pivot pin 35 corresponds to the “support shaft” of claim 1.

  A pair of arms 38 a and 38 b are erected and coupled to the gear case 32. The pair of arms 38a and 38b are rotatably supported by the sleeve 37. As described above, the lower fixing bracket 34 supports the steering column 2 via the pivot pin 35.

  As shown in FIGS. 1 and 2, the electric power steering apparatus 100 is configured such that the steering column 2 is moved around the pivot pin 35 so that the steering wheel 8 moves in the vertical direction (in the direction of the arrow shown in FIG. 2) when viewed from the driver. And a release mechanism 60 capable of switching between restricting the swing of the steering column 2 and releasing the restriction. Hereinafter, the tilt mechanism 50 and the release mechanism 60 will be described.

  The tilt mechanism 50 includes a column bracket 51 having a rectangular cross section fixed to the upper column tube 21 so as to surround the outer periphery of the upper column tube 21, a support bracket 52 fixed to the upper fixing bracket 33 and supporting the column bracket 51, and a support And a guide pin 53 for connecting the column bracket 51 to the bracket 52 so that the column bracket 51 is movable.

  The support bracket 52 has a pair of side walls 52 a extending so as to sandwich both side walls 51 a of the column bracket 51. The guide pins 53 are provided through the both side walls 52 a of the support bracket 52 and the both side walls 51 a of the column bracket 51. Guide holes 52 b for guiding the movement of the guide pins 53 are formed in both side walls 52 a of the support bracket 52. The guide hole 52 b is formed in a direction substantially orthogonal to the axial direction of the steering column 2. As the guide pin 53 moves along the guide hole 52 b, the column bracket 51 moves along the inner peripheral surfaces of the side walls 52 a of the support bracket 52. As a result, the steering column 2 swings around the pivot pin 35, and the steering wheel 8 moves up and down.

  Further, guide holes 51b (see FIG. 3) for guiding the movement of the guide pins 53 are formed in both side walls 51a of the column bracket 51 along the axial direction of the steering column 2. As the guide pin 53 moves along the guide hole 51 b, the column bracket 51 moves along the inner peripheral surfaces of the side walls 52 a of the support bracket 52. Thereby, the upper column tube 21 moves in the axial direction together with the upper shaft 11, and the steering wheel 8 moves in the front-rear direction as viewed from the driver. As described above, the electric power steering apparatus 100 includes a tilt mechanism 50 and a mechanism that enables the steering wheel 8 to move in the front-rear direction.

  As shown in FIG. 2, the release mechanism 60 has an operation lever 61 that is rotatably attached to the guide pin 53 and can be operated by the driver at the driver's seat. By operating the operation lever 61, the both side walls 51a of the column bracket 51 are tightened and released by the both side walls 52a of the support bracket 52. Specifically, tightening and releasing thereof are performed by the action of a cam that rotates as the operating lever 61 is operated.

  When the operation lever 61 is in the tightening position, the side walls 51a of the column bracket 51 are tightened by the side walls 52a of the support bracket 52, and the movement of the column bracket 51 with respect to the support bracket 52 is restricted. The swing of the column 2 is restricted. On the other hand, when the operation lever 61 is in the open position, the side walls 51a of the column bracket 51 are not tightened by the side walls 52a of the support bracket 52, and the column bracket 51 can be moved relative to the support bracket 52. Therefore, the restriction on the swinging of the steering column 2 is released, and the steering column 2 becomes swingable.

  Here, when the operation lever 61 is operated from the tightening position to the release position, the steering wheel 8 is moved until the guide pin 53 comes into contact with the end of the guide hole 52b by the weight of the electric power steering device 100, that is, the steering column. 2 falls to the lower end position of the swing range 2 and an impact and a hitting sound are generated.

  In order to prevent this, a torsion spring 56 shown in FIG. 6 is provided on the outer periphery of the pivot pin 35 for weight compensation of the electric power steering apparatus 100.

  4 to 6, the torsion spring 56 has a coil portion 56a wound around the outer periphery of the sleeve 37 on the outer periphery of the pivot pin 35, and one end portion 56b of the coil portion 56a abuts on the gear case 32 and the other end portion. 56 c is in contact with the lower fixing bracket 34. The torsion spring 56 has two coil portions 56 a, and the other end portions 56 c of the torsion spring 56 are in contact with the lower fixing bracket 34.

  The torsion spring 56 is provided in such a manner that both end portions 56b and 56c of the coil portion 56a are in contact with the gear case 32 and the lower fixing bracket 34, respectively, and therefore when the restriction of the swing of the steering column 2 is released by the release mechanism 60. Is compressed between the gear case 32 and the lower fixing bracket 34 to generate a torsional reaction force. Thus, the torsion spring 56 applies a biasing force against the weight of the electric power steering device 100 to support the weight of the electric power steering device 100. Therefore, even if the operation lever 61 is operated from the tightening position to the open position, the occurrence of an impact is prevented.

  The torsion spring 56 has two coil portions 56a, and the other end portion 56c that abuts the lower fixing bracket 34 is formed between the coil portions 56a. Therefore, the spring constant can be increased and the urging force can be balanced with the electric power steering. It can be applied to the device 100.

  The torsional reaction force of the torsion spring 56 is desirably set so as to balance the weight of the electric power steering device 100 when the operation lever 61 is in the open position. By setting in this way, the driver can move the steering wheel 8 upward and downward with a small force. However, the torsional reaction force of the torsion spring 56 is not limited to such a setting, and can be freely set according to the design concept of the vehicle body.

  Since both ends of the torsion spring 56 are provided in contact with the gear case 32 and the lower fixing bracket 34, the gear case 32 and the lower fixing bracket 34 are electrically connected via the torsion spring 56. As a result, the electrical system around the steering wheel 8 of the vehicle is reliably conducted to the vehicle body through the steering shaft 1 and the torsion spring 56. Thus, the torsion spring 56 also functions as an electrical system ground path. Since the torsion spring 56 functions as a ground path for the electrical system, the reliability of the electrical system operation is improved. The electrical system is an operation switch or horn provided on the steering wheel 8.

  According to the above embodiment, there exists an effect shown below.

  Since the torsion spring 56 for weight compensation of the electric power steering apparatus 100 is provided on the outer periphery of the pivot pin 35 that is the swing center of the steering column 2 when the steering wheel 8 is tilt-adjusted, it may interfere with other parts. Absent. Therefore, the degree of freedom of layout of other parts is improved, and the layout of mounting the electric power steering apparatus 100 on the vehicle is not limited, and the workability of mounting on the vehicle is improved.

  Further, since the torsion spring 56 is provided on the outer periphery of the pivot pin 35, which is a basic component of the electric power steering apparatus 100, it is not necessary to add a mounting seat or the like when the torsion spring 56 is provided. Therefore, the structure of the electric power steering apparatus 100 can be simplified and the cost can be reduced.

  In addition, the torsion spring 56 is provided with both ends thereof in contact with the gear case 32 and the lower fixing bracket 34, respectively, and functions as an electrical system ground path around the steering wheel 8, so that the reliability of the electrical system is reliable. improves.

  The electric power steering apparatus 100 is configured such that the support bracket 52 moves relative to the upper fixing bracket 33 when an excessive load is applied to the steering shaft 1 through the steering wheel 8 in the event of a vehicle collision. An impact absorbing mechanism is provided for absorbing an impact at the time of a vehicle collision as the bracket 52 moves. If a weight compensation spring is provided between the upper fixing bracket 33 and the gear case 32, the support bracket 52 contacts the spring during operation of the shock absorbing mechanism, and the shock absorbing mechanism has desired operating characteristics. There is a risk of not exhibiting. However, in this embodiment, since the torsion spring 56 for weight compensation is provided on the outer periphery of the pivot pin 35, the torsion spring 56 does not adversely affect the operation of the shock absorbing mechanism, and the shock absorbing mechanism can be operated stably. Can be secured.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  For example, in the above-described embodiment, it has been described that the torsion spring 56 is provided in such a manner that both ends thereof are in contact with the gear case 32 and the lower fixing bracket 34, respectively. However, it is not necessary that both end portions of the torsion spring 56 are always in contact with the gear case 32 and the lower fixing bracket 34, and the electric power steering apparatus 100 is dropped by its own weight when the operation lever 61 is operated from the tightening position to the open position. Thus, both end portions of the torsion spring 56 may abut against the case 32 and the lower fixing bracket 34.

DESCRIPTION OF SYMBOLS 100 Electric power steering apparatus 1 Steering shaft 2 Steering column 8 Steering wheel 11 Upper shaft 12 Lower shaft 13 Electric motor 21 Upper column tube 22 Lower column tube 32 Gear case 33 Upper fixing bracket 34 Lower fixing bracket 35 Pivot pin (support shaft)
38a, 38b Arm 50 Tilt mechanism 51 Column bracket 52 Support bracket 52b Guide hole 53 Guide pin 56 Torsion spring 56a Coil part 56b Coil part one end part 56c Coil part other end part 60 Release mechanism 61 Operation lever

Claims (1)

An electric power steering device that assists the steering force applied by the driver to the steering wheel with the rotational torque of the electric motor,
A steering shaft to which the steering wheel is coupled;
A steering column that rotatably supports the steering shaft;
A fixed bracket fixed to the vehicle body and supporting the steering column via a support shaft;
A gear case that houses a worm wheel to which the rotational torque of the electric motor is transmitted;
A tilt mechanism capable of swinging the steering column about the support shaft so that the steering wheel moves in the vertical direction;
A release mechanism capable of switching between regulation of the swing of the steering column and release of the regulation;
A spring that is provided on the outer periphery of the support shaft and that applies a biasing force against the weight of the electric power steering device when the restriction of the swing of the steering column is released by the release mechanism ,
Both ends of the spring are always provided in contact with the fixed bracket and the gear case, respectively, and when the restriction of the swing of the steering column is released by the release mechanism, the spring is interposed between the fixed bracket and the gear case. An electric power steering apparatus , wherein the torsion spring generates a torsional reaction force, and the spring functions as a ground path for an electrical system around the steering wheel .

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