JP4379442B2 - Electric power steering device - Google Patents

Description

  The present invention relates to an electric power steering apparatus, and more particularly to a technique for preventing interference between an electric assist mechanism and another apparatus during a telescopic operation.

  In a steering system for an automobile, a so-called power steering device that performs steering assist using an external power source is widely adopted.

  Conventionally, a vane type hydraulic pump is generally used as a power source for a power steering apparatus, and many of these hydraulic pumps are driven by an engine. However, this type of power steering device has a large engine drive loss due to the constant drive of the hydraulic pump (several horsepower to about 10 horsepower at the maximum load), and is therefore adopted for light vehicles with small displacement. It was difficult, and it was unavoidable that the fuel consumption of a car with a relatively large displacement was reduced to a level that could not be ignored. In order to solve these problems, an electric power steering device (hereinafter referred to as EPS) using an electric motor as a power source has attracted attention in recent years. In EPS, there is no direct engine drive loss because an in-vehicle battery is used as a power source for the electric motor, and the electric motor is started only at the time of steering assist, so the running fuel consumption is reduced (engine drive loss related to the alternator). In addition, the electronic control is extremely easy. The EPS is classified into a column assist type, a rack assist type, and the like depending on the mounting portion of the electric motor. Currently, the column assist type, which is excellent in manufacturing cost, installation space, and the like, is mainly used.

  On the other hand, since an automobile steering device is used (steered) by an unspecified number of drivers, it is desirable that the position of the steering wheel can be adjusted in accordance with an individual's physique and driving posture. In order to respond to such demands, not only passenger cars but also freight cars and the like are increasingly adopting a tilt mechanism and a telescopic mechanism. The tilt mechanism is a mechanism for adjusting the position of the steering wheel in the vertical direction, such as a tilt pivot for swingably supporting the steering column and a tilt lever for fixing the steering column at a desired position (swing angle). It is made up of. The telescopic mechanism is a mechanism for adjusting the position of the steering wheel in the front-rear direction (the axial direction of the steering shaft). It consists of a telescopic lever that fixes the steering shaft with the amount of expansion and contraction.

  In a conventional hydraulic power steering apparatus, the following method has been adopted in order to establish a tilt mechanism and a telescopic mechanism.

  For example, in a steering apparatus described in Japanese Patent Laid-Open Nos. 5-262239 and 6-40342, a tilt mechanism and a telescopic mechanism are formed in the same portion, and a single lever is unlocked. A tilt operation and a telescopic operation can be performed. However, in the column assist type electric power steering apparatus, when such a method is adopted, the electric assist mechanism mounted on the steering column greatly moves in the axial direction during telescopic operation. Therefore, it is necessary to provide a large space in the vicinity of the instrument panel having a high device density in order to secure a moving space for the electric assist mechanism, and there is a problem that the degree of freedom in designing other devices is reduced.

  Further, in the steering apparatus described in Japanese Utility Model Publication No. Hei 6-78155, a swing tilt type tilt mechanism is provided on the top of the telescopic mechanism, and the tilt operation and the telescopic operation are performed by the tilt lever and the telescopic lever, respectively. I have to. However, in the column assist type electric power steering apparatus, when such a method is adopted, in addition to the above-described problems caused by the electric assist mechanism moving greatly in the axial direction during telescopic operation, the electric assist mechanism is interposed. In combination with this, the overall length of the steering device becomes very long, and it is difficult to mount the steering device on a car.

  The present invention has been made in view of the above situation, and an object thereof is to provide an electric power steering device that prevents interference between the electric assist mechanism and other devices during telescopic operation.

In order to solve the above-mentioned problems, in the invention of claim 1, the upper shaft member is composed of an upper shaft member and a lower shaft member. A steering shaft supported so as to be slidable and capable of transmitting rotation;
The upper column member and the lower column member comprise an upper column member and a lower column member, and the upper column member and the lower column member support the steering shaft in a rotatable manner. The upper column member is telescopically positioned with respect to the lower column member. A steering column whose lower end portion is fitted in the lower column member so as to be slidable in the axial direction for adjustment ;
A telescopic lock / release mechanism attached to the lower column member and capable of fixing and adjusting the axial position of the steering wheel;
In an electric power steering device comprising an electric assist mechanism for assisting the steering force of the steering wheel,
The upper shaft member is externally fitted to the lower shaft member;
The upper shaft member is supported by bearings at both axial upper and lower ends of the inner peripheral surface of the upper column member,
A sleeve is interposed between the upper column member and the lower column member in the radial direction between the upper column member and the lower column member,
It is proposed that the upper column member is made of steel pipe, the lower column member is made of aluminum alloy, and the lower column member is integrated with the housing of the electric assist mechanism.

According to such a configuration of the present invention , interference between the electric assist mechanism and the peripheral device during telescopic operation does not occur.

The invention of claim 2 proposes the electric power steering apparatus according to claim 1, wherein the lower column member and the housing of the electric assist mechanism are cast products made of aluminum alloy .

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a side view showing a compartment side portion of the electric power steering apparatus according to the first embodiment of the present invention, and reference numeral 1 in FIG. 1 denotes a steering column. The steering column 1 is fixed to cross members 7 and 9 which are vehicle body structural members via a tilt bracket 3 and a pivot pin 5. The steering column 1 has a steering upper shaft 11 rotatably supported therein, and an electric assist mechanism 19 including an electric motor 13, a reduction gear box 15, an output shaft 17, and the like is integrated at the tip. Yes. In the case of the present embodiment, the reduction gear box 15 is a cast product made of an aluminum alloy, and a pivot pin 5 is rotatably inserted in a pivot bracket 21 fixed to the front end surface thereof. In FIG. 1, reference numeral 23 denotes a steering intermediate shaft, which is connected to the tip of the output shaft 17 through a universal joint 25.

  A steering wheel 27 is attached to the rear end of the steering upper shaft 11, and when the driver rotates the steering wheel 27, the rotational force is increased by the electric assist mechanism 19, and then via the output shaft 17. It is transmitted to the steering intermediate shaft 23 and further transmitted to the steering gear at the lower part of the vehicle body via a steering lower shaft (not shown).

  In the first embodiment, as shown in FIG. 2, the steering column 1 includes a steel pipe inner column 31 located on the steering wheel 27 side and an outer column 33 extending rearward from the reduction gear box 15. It has become. The steering upper shaft 11 is composed of an outer shaft 35 on the steering wheel 27 side and an inner shaft 37 on the reduction gear box 15 side. In the case of the first embodiment, the inner column 31 is slidably fitted in the outer column 33, while the outer shaft 35 is slidably fitted only in the axial direction to the inner shaft 37 via the serration. A telescopic mechanism 39 is configured. In FIG. 2, members denoted by reference numerals 41 and 43 are rolling bearings interposed between the inner column 31 and the outer shaft 35.

  As shown in FIGS. 2 and 3 (A-A enlarged sectional view in FIG. 2), a pair of left and right substantially cylindrical lock blocks 51 are held at the lower end of the rear portion of the outer column 33. Each of the lock blocks 51 has an inclined surface 53 facing the outer peripheral surface of the inner column 31 on the inner side, and an outer end surface of the lock block 51 projects from the side surface of the outer column 33 by a predetermined amount. A through hole 54 is formed in the shaft center of the lock block 51, while an arc-shaped long hole 55 centering on the pivot pin 5 is formed in the tilt bracket 3. A lock bolt 57 is fitted into the hole 55. The lock bolt 57 is screwed into a nut 61 integrated with the lock lever 59. In the drawing, a member denoted by reference numeral 63 is a bolt that fastens the lock lever 59 and the nut 61.

  The operation of the first embodiment will be described below.

  In the case where the position of the steering wheel 27 becomes inappropriate due to the change of the driver or the like, in the electric power steering apparatus of the first embodiment, the driver first rotates the lock lever 59 to the unlock side, and then the lock bolt 57 The nut 61 is loosened. Then, the axial force of the lock bolt 57 acting on the tilt bracket 3 and the lock block 51 disappears, and the steering column 1 can swing a predetermined amount about the pivot pin 5, and at the same time, the inner column 31 and the outer shaft 35. Can slide a predetermined amount with respect to the outer column 33 and the inner shaft 37. As a result, the driver can tilt or telescopically operate the steering column 1 and adjust the steering wheel 27 to a desired position.

  At this time, since the telescopic mechanism 39 is provided above the electric assist mechanism 19, the electric assist mechanism 19 is not moved by the telescopic operation. Further, since the electric assist mechanism 19 is located immediately above the pivot pin 5, the amount of movement of the electric assist mechanism 19 due to the tilt operation can be suppressed to a very small value. Therefore, unlike the above-described conventional apparatus, it is not necessary to secure a large movement space for the electric assist mechanism 19 in the vicinity of the steering column 1, and the degree of freedom in designing the apparatus in the vicinity of the instrument panel can be increased.

  When the position adjustment of the steering wheel 27 is completed, the driver rotates the lock lever 59 to the lock side, and tightens the nut 61 with respect to the lock bolt 57 in the opposite direction. Then, the tilt bracket 3 is sandwiched between the lock bolt 57 and the nut 61 and elastically deformed, and the lock block 51 is pushed inward. Accordingly, the outer end surface of the lock block 51 is pressed against the inner side surface of the tilt bracket 3, while the inclined surface 53 of the lock block 51 is pressed against the outer peripheral surface of the inner column 31. As a result, the steering column 1 is fixed in the tilt direction by the frictional force between the tilt bracket 3 and the lock block 51, and at the same time is fixed in the telescopic direction by the frictional force between the lock block 51 and the inner column 31. The

  As described above, in the first embodiment, since the tilt operation and the telescopic operation can be performed simultaneously by operating the single lock lever 59, the position adjustment of the steering wheel 27 becomes extremely easy, and the entire length of the steering column 1 is increased. Could also be shortened.

  FIG. 4 shows a steering column 1 according to a second embodiment of the present invention in a longitudinal section of the main part. 2nd Embodiment changes only the fitting part of the inner column 31 and the outer column 33 with respect to 1st Embodiment mentioned above, Since another structure and effect | action are the same, the overlapping description is Omitted.

  As shown in FIG. 4, in the second embodiment, a steel pipe sleeve 71 is externally fitted and fixed (welded) to the outer peripheral end of the inner column 31, and the outer column 33 and the sleeve 71 are slid. The structure which moves is taken. Thereby, the support rigidity of the inner column 31 by the outer column 33 is improved, and the possibility that the inner column 31 is deformed even when the driver puts weight on the steering wheel 27 is reduced. An annular groove 73 is formed on the inner peripheral surface of the sleeve 71 at a position corresponding to the rolling bearing 43 so that unnecessary pressing force or the like does not act on the rolling bearing 43.

  Although description of specific embodiment is finished above, the aspect of the present invention is not limited to the above embodiment. For example, in the above-described embodiments, the steering column is fixed in the tilt direction and the telescopic direction using a lock block, but various known fixing methods can be employed. In addition, the specific configuration of the tilt mechanism and the telescopic mechanism including the electric assist mechanism can be changed as appropriate without departing from the gist of the present invention.

(The invention's effect)
As described above, according to the electric power steering device of the present invention, interference between the electric assist mechanism and peripheral devices during telescopic operation does not occur, and a large moving space for the electric assist mechanism is secured in the vicinity of the steering column. No need to do.

It is explanatory drawing which shows the structure in the compartment side of the steering device which concerns on this invention. It is a principal part sectional side view of a steering column concerning a 1st embodiment of the present invention. It is an AA expanded sectional view in FIG. It is a principal part longitudinal cross-section of the steering column which concerns on 2nd Embodiment of this invention.

Explanation of symbols

1 ... Steering column 3 ... Tilt bracket 5 ... Pivot pin 11 ... Steering upper shaft 27 ... Steering wheel 31 ... Inner column 33 ... Outer column 35 ... Outer shaft 37 ... Inner shaft 51 ... Lock Block 57 ... Lock bolt 59 ... Lock lever 61 ... Nut 71 ... Sleeve

Claims (2)

Composed of a upper shaft member and the lower shaft member, the steering shaft is said upper shaft member steering wheel is mounted on the upper end, which is and slidably and rotation transmission can be supported in the axial direction with respect to said lower shaft member When,
The upper column member and the lower column member comprise an upper column member and a lower column member, and the upper column member and the lower column member support the steering shaft in a rotatable manner. The upper column member is telescopically positioned with respect to the lower column member. A steering column whose lower end portion is fitted in the lower column member so as to be slidable in the axial direction for adjustment ;
A telescopic lock / release mechanism attached to the lower column member and capable of fixing and adjusting the axial position of the steering wheel;
In an electric power steering device comprising an electric assist mechanism for assisting the steering force of the steering wheel,
The upper shaft member is externally fitted to the lower shaft member;
The upper shaft member is supported by bearings at both axial upper and lower ends of the inner peripheral surface of the upper column member,
A sleeve is interposed between the upper column member and the lower column member in the radial direction between the upper column member and the lower column member,
The upper column member is made of a steel pipe, the lower column member is made of an aluminum alloy, and the lower column member is integrated with a housing of the electric assist mechanism. The electric power steering apparatus according to claim 1 , wherein the lower column member and the housing of the electric assist mechanism are cast products made of an aluminum alloy.

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