JP2012041014A - Rack and pinion type steering gear unit - Google Patents

Abstract

An object of the present invention is to simplify the shape of a set screw cylinder 22a, to reduce the manufacturing cost of the set screw cylinder 22a, and to assemble a ball bearing 16 and a seal ring 27a to a pinion shaft 6. Realizes a structure that can integrate the assembly work.
An inner peripheral surface of the holding screw cylinder 22a is a cylindrical surface having no flange projecting radially inward. Further, the seal ring 27 a is formed by reinforcing a portion near the inner diameter of the annular elastic member 31 with an annular cored bar 32. In a state where the seal ring 27a is fitted and fixed to the intermediate portion of the pinion shaft 6, the outer peripheral edge of the elastic member 31 is brought into sliding contact with the inner peripheral surface of the holding screw cylinder 22a over the entire periphery.
[Selection] Figure 1

Description

  The present invention relates to an improvement of a rack and pinion type steering gear unit that constitutes a steering device for giving a steering angle to a steering wheel of an automobile. Specifically, it is intended to realize a structure capable of reducing the manufacturing cost while ensuring the sealing performance of the pinion shaft mounting portion.

   A steering device including a rack and pinion type steering gear unit that uses a rack and pinion as a mechanism for converting a rotational motion input from a steering wheel into a linear motion for giving a steering angle is disclosed in, for example, Patent Documents 1 to 3. 3 has been widely known. In addition, the rack and pinion type steering gear unit can be configured to be small and light, and since it has high rigidity and a good steering feeling, it is actually widely used. 3 to 5 show a structure described in Patent Document 2 as an example of a steering apparatus incorporating such a rack and pinion type steering gear unit. In this steering device, the movement of the steering shaft 2 that rotates in accordance with the operation of the steering wheel 1 is transmitted to the pinion shaft 6 that is the input shaft of the steering gear unit 5 through the universal joints 3 and 3 and the intermediate shaft 4. To do.

  The steering gear unit 5 is formed by meshing pinion teeth 7 provided on a part of the pinion shaft 6 in the axial direction with rack teeth 9 provided on the front surface of the rack shaft 8. Each of the pinion shaft 6 and the rack shaft 8 is housed in a casing 10. The casing 10 includes a main storage portion 11 and a sub storage portion 12 each having a cylindrical shape. Of these, the main storage portion 11 is open at both ends. Moreover, this sub-accommodating part 12 is provided in a part of the main accommodating part 11, and one end is opened. The central axis of the main storage portion 11 and the central axis of the sub storage portion 12 are in a twisted positional relationship with each other. The rack shaft 8 is inserted through the main storage portion 11 of the rack shaft 8 so as to be axially displaceable, and both end portions protrude from the main storage portion 11. And the base end part of the tie rods 14 and 14 is couple | bonded with the both ends via the spherical couplings 13 and 13, respectively. The tip portions of the tie rods 14 and 14 are respectively connected to the tip portions of knuckle arms (not shown) by pivots. The rack shaft 8 does not rotate around its own central axis due to the engagement of the pinion teeth 7 and the rack teeth 9.

  The pinion shaft 6 supports the tip half of the pinion teeth 7 in the sub-accommodating portion 12 so that it can only rotate. For this purpose, the tip end portion of the pinion shaft 6 is supported by the radial needle bearing 15 at the back end portion of the auxiliary storage portion 12. Further, the intermediate portion of the pinion shaft 6 is supported by a single row ball bearing 16 such as a deep groove type, a three-point contact type, or a four-point contact type at a portion near the opening of the sub storage portion 12. Of the inner ring 17 and the outer ring 18 constituting the ball bearing 16, the inner ring 17 includes an inner diameter side step surface 19 formed at an intermediate portion of the pinion shaft 6 and a conical stopper locked to the intermediate portion of the pinion shaft 6. It is sandwiched between the wheel 20. In addition, the outer ring 18 is formed on the outer diameter side step surface 21 which is the step portion described in the claims and formed in the middle portion of the inner peripheral surface of the sub storage portion 12, and the opening portion of the sub storage portion 12. It is clamped between the screwed holding screw cylinder 22. With this configuration, the front half of the pinion shaft 6 is supported in the sub-accommodating portion 12 so as to be able to support a radial load and a thrust load (to prevent rotation in the axial direction).

  Further, a cylinder tube portion 23 is provided on the opposite side of the sub storage portion 12 in the diameter direction of the main storage portion 11, and a pressing block 24 is fitted in the cylinder tube portion 23. A spring 26 is provided between the cover 25 screwed into the opening of the cylinder cylinder 23 and the pressing block 24 to press the pressing block 24 toward the rack shaft 8. The rack shaft 8 is elastically pressed toward the pinion shaft 6 to eliminate backlash at the meshing portion between the pinion teeth 7 and the rack teeth 9. Further, the meshing state of the meshing part is properly maintained regardless of the force in the direction away from the pinion shaft 6 applied to the rack shaft 8 with the power transmission at the meshing part of the teeth 7 and 9. .

  When the steering angle is applied to the left and right front wheels, when the pinion shaft 6 is rotated by the operation of the steering wheel 1, the rack shaft 8 is moved based on the engagement of the pinion teeth 7 and the rack teeth 9. Displace in the axial direction. Then, the tie rods 14 and 14 coupled to both ends of the rack shaft 8 are pushed and pulled to give a desired rudder angle to the front wheels.

  The steering gear unit 5 as described above is generally installed in the engine room of an automobile with the pinion shaft 6 positioned upward (with the right side in FIG. 5 facing upward). Therefore, a structure for preventing foreign matter such as muddy water that gets down with traveling from entering the casing 10 is required. Of these, the opening portions at both ends of the main storage portion 11 are formed by spanning bellows 37 and 37 (see FIG. 3) between both ends of the main storage portion 11 and both ends of the rack shafts 8. Seal.

  On the other hand, the opening of the sub-accommodating portion 12 is sealed by a seal ring 27 fitted in the set screw cylinder 22. The holding screw cylinder 22 is made by machining a material such as a steel material, and has an inward flange portion 28 formed at an intermediate portion of the inner peripheral surface. The seal ring 27 is configured so that the inner periphery of the set screw cylinder 22 is fitted to the outer peripheral surface of the pinion shaft 6 with the inner periphery thereof being fitted to the outer space side of the inward flange portion 28. Slid in contact with

  In the case of the conventional structure as described above, the shape of the holding screw cylinder 22 to which the seal ring 27 is attached is complicated, and it is necessary to manufacture by a cutting process that is troublesome and requires processing time. The increase in cost is inevitable. In the process of assembling the steering gear unit 5, the ball bearing 16 is assembled to the pinion shaft 6, and the seal ring 27 is assembled to the set screw cylinder 22. In this way, since the members 16 and 27 arranged adjacent to each other in the axial direction are assembled to separate members, the assembly work cannot be consolidated, and the efficiency of the assembly work of the steering gear unit 5 is improved. Is disadvantageous.

JP 2007-186185 A JP 2009-184591 A JP 2009-190426 A

  In view of the circumstances as described above, the present invention can simplify the shape of the holding screw cylinder, can reduce the manufacturing cost of the holding screw cylinder, and can provide a bearing and a seal ring such as a ball bearing. Both were invented to realize a structure that can be assembled into a pinion shaft so that the assembly work can be consolidated.

The rack and pinion type steering gear unit of the present invention is similar to the conventionally known rack and pinion type steering gear unit, and includes a casing, a rack shaft, a pinion shaft, a bearing, a holding screw cylinder, A seal ring.
Of these, the casing has a cylindrical main storage portion that is open at both ends, and a cylindrical sub storage portion that is provided at a twisted position with respect to the main storage portion and is open at one end.
The rack shaft is provided with rack teeth on the front surface, and is installed in the main housing portion of the casing so as to be capable of axial displacement.
In addition, the pinion shaft is configured such that pinion teeth formed on the front half portion in the axial direction mesh with the rack teeth, and the base half portion in the axial direction protrudes outward from the opening of the auxiliary storage portion of the casing. Therefore, it is arranged in the sub-accommodating portion.
The bearing is provided between the outer peripheral surface of the intermediate portion of the pinion shaft and a portion near the opening of the inner peripheral surface of the sub storage portion, and rotatably supports the pinion shaft in the sub storage portion.
Further, the set screw cylinder is screwed to the opening side end portion of the inner peripheral surface of the sub-accommodating portion, and the bearing is pressed against the step portion provided in the intermediate portion of the inner peripheral surface of the sub-accommodating portion. .
Furthermore, the seal ring is provided between the inner peripheral surface of the set screw cylinder and the outer peripheral surface of the intermediate portion of the pinion shaft.

In particular, in the rack and pinion type steering gear unit of the present invention, the inner peripheral surface of the set screw cylinder is a cylindrical surface having no flange protruding radially inward.
The seal ring is formed by reinforcing a portion close to the inner diameter of the annular elastic material with an annular cored bar, and the outer peripheral edge of the elastic material is fixed to the intermediate portion of the pinion shaft. The inner periphery of the holding screw cylinder is in sliding contact with the entire circumference.

  When implementing the rack and pinion type steering gear unit of the present invention as described above, specifically, as in the invention described in claim 2, the bearing is a deep groove type, a three-point contact type, or a four-point type. As a single-row ball bearing such as a contact type, an inner ring constituting the ball bearing is externally fitted and fixed to an intermediate portion in the axial direction of the pinion shaft while preventing axial displacement. Further, the outer ring constituting the ball bearing is sandwiched between the stepped portion and the holding screw cylinder, and is fitted and fixed in the sub-accommodating portion while preventing displacement of the pinion shaft in the axial direction. . Further, a stepped portion is formed in a portion closer to the opening of the sub-accommodating portion than a portion where the inner ring is fitted on the outer peripheral surface of the intermediate portion of the pinion shaft. Then, the seal ring is externally fitted and fixed to the pinion shaft in a state where a portion closer to the inner diameter of one axial surface is abutted against the stepped portion.

  Further, when implementing the present invention, preferably, as in the invention described in claim 3, the outer diameter of the set screw cylinder is set to be smaller than the base half portion screwed into the opening end portion of the sub-accommodating portion. The size is reduced at the front half projecting out of the sub storage portion. Then, the outer peripheral edge of the seal ring is brought into sliding contact with the inner peripheral surface of the front half portion.

  According to the rack and pinion type steering gear unit of the present invention configured as described above, the shape of the holding screw cylinder can be simplified, and the manufacturing cost of the holding screw cylinder can be reduced. In addition, by assembling both a bearing such as a ball bearing and a seal ring to the pinion shaft, it is possible to consolidate the assembling work and reduce the cost by improving the efficiency of the assembling work.

First, since the inner peripheral surface of the holding screw cylinder is a cylindrical surface that does not have a flange projecting radially inward, it is possible to manufacture by forging with a short processing time, and to reduce the manufacturing cost. Can do. In addition, the weight can be reduced by omitting the collar.
Further, in the process of assembling the rack and pinion type steering gear unit, both the bearing and the seal ring are externally fitted to the pinion shaft. For this reason, the assembly work of these bearings and seal rings can be integrated, and the cost can be reduced by increasing the efficiency of the assembly work.

The figure equivalent to the expanded AA cross section of FIG. 4 which shows the 1st example of embodiment of this invention. The figure similar to FIG. 1 which shows the 2nd example. The partial cutting side view which shows an example of the steering device for motor vehicles incorporating the rack and pinion type steering gear unit. BB sectional drawing of FIG. The expanded AA sectional view of FIG.

[First example of embodiment]
FIG. 1 shows a first example of an embodiment of the present invention. The feature of the present invention including this example is the structure of the sealing device provided between the opening of the sub-accommodating portion 12 of the casing 10 and the intermediate portion of the pinion shaft 6. Since the structure and operation of the other parts are the same as those of the conventional structure shown in FIG. 5 described above, the same parts are denoted by the same reference numerals, and redundant description is omitted or simplified. The explanation will be focused on.

  The holding screw cylinder 22a incorporated in the structure of this example is formed by subjecting a material such as carbon steel to a cylindrical intermediate material, and then forming a male screw portion 29 at a required location by die processing. The inner peripheral surface of the set screw cylinder 22a is a cylindrical surface that does not have a flange portion protruding radially inward. In the case of this example, the inner diameter increases toward the opening edge at the portion closer to the base end (left end in FIG. 1) located on the inner space side of the sub storage portion 12 in the assembled state to the sub storage portion 12. A tapered surface 30 inclined in the direction is formed. The tapered surface 30 functions as a draft for extracting the die from the inner diameter side when the holding screw cylinder 22a is processed by forging. Of the inner peripheral surface of the set screw cylinder 22a, the axially intermediate portion or the tip portion (the right end portion in FIG. 1) that is out of the tapered surface 30 does not change its inner diameter in the axial direction (no or little). It is just a cylindrical surface. Further, the outer diameter of the holding screw cylinder 22a is projected beyond the base half portion where the male screw portion 29 is formed so as to be screwed into the opening end portion of the sub storage portion 12. It is made small in the half (the right half in FIG. 1). Accordingly, the thickness dimension of the set screw cylinder 22a in the radial direction is large in the base half and small in the tip half. With this configuration, the weight of the holding screw cylinder 22a is reduced.

  The seal ring 27a that constitutes the sealing device together with the holding screw cylinder 22a is formed by reinforcing a portion near the inner diameter of an annular elastic member 31 such as an elastomer such as rubber by an annular cored bar 32. The seal ring 27a is slidably contacted with the inner peripheral surface of the holding screw cylinder 22a over the entire circumference in a state where the seal ring 27a is fitted and fixed to the intermediate portion of the pinion shaft 6. ing. The outer peripheral edge portion of the elastic material 31 is easily elastically deformed by reducing the thickness dimension in the axial direction. For this reason, the surface pressure of the sliding contact portion between the outer peripheral edge portion and the inner peripheral surface of the set screw cylinder 22a and the area of the accumulation portion are made appropriate, and the sliding torque of the sliding contact portion becomes excessive. Can be prevented.

  In the case of this example, the portion closer to the opening of the secondary storage portion 12 (rightward in FIG. 1) than the portion where the inner ring 17 constituting the ball bearing 16 is fitted on the outer peripheral surface of the intermediate portion of the pinion shaft 6. In addition, a stepped portion 33 which is the second stepped portion described in the claims is formed. The seal ring 27a is externally fitted and fixed to the pinion shaft 6 with a portion near the inner diameter of one surface in the axial direction abutting against the step portion 33. In this state, the axial position of the stepped portion 33 is restricted so that the outer peripheral edge of the seal ring 27a is in sliding contact with the tip end portion of the inner peripheral surface of the holding screw cylinder 22a. Of the pinion shaft 6, the outer diameter of the portion that fits the seal ring 27 a adjacent to the stepped portion 33 is coupled to the yoke of the universal joint 3 (see FIG. 3) at the tip of the pinion shaft 6. It is larger than the outer diameter of the part. Accordingly, the seal ring 27a can be externally supported by a portion adjacent to the stepped portion 33 without causing damage such as scratches on the inner peripheral surface.

  The seal ring 27a is externally fitted to the pinion shaft 6 with a sufficiently large interference fit, and the stepped portion 33 faces upward when the steering gear unit is assembled to the vehicle. Furthermore, both the pinion shaft 6 and the cored bar 32 are made of steel, and their linear expansion coefficients are almost the same. Therefore, the tightening margin of the seal ring 27a with respect to the pinion shaft 6 does not decrease regardless of temperature changes during use. For this reason, the seal ring 27a does not come out of the pinion shaft 6 carelessly during use.

  According to the rack and pinion type steering gear unit of this example configured as described above, the shape of the set screw cylinder 22a can be simplified, and the manufacturing cost of the set screw cylinder 22a can be kept low. That is, the inner peripheral surface of the holding screw cylinder 22a is a simple cylindrical surface that does not have a flange portion projecting radially inward and is simply formed with a tapered surface 30 for punching at a portion near the base end. Therefore, it becomes possible to manufacture by forging with a short processing time. The tapered surface 30 functions as a guide surface when the seal ring 27a is inserted into the holding screw cylinder 22a. Of the inner peripheral surface of the holding screw cylinder 22a, the portion that is axially removed from the tapered surface 30 needs to be a smooth surface in order to slide the outer peripheral edge of the seal ring 27a. For such a smooth surface, a cored bar (core) whose outer peripheral surface is a smooth surface is used during forging, and the holding screw cylinder is pressed while strongly pressing a part of the material against the outer peripheral surface of the cored bar. It can be easily formed by processing 22a. However, the smooth surface may be formed by machining. Since the area of the part to be machined is limited, the increase in machining cost is limited. Accordingly, the holding screw cylinder 22a having the required performance can be easily manufactured at low cost.

  Further, by assembling both the ball bearing 16 and the seal ring 27a to the pinion shaft 6, the assembling work can be integrated and the cost can be reduced by improving the efficiency of the assembling work. That is, in the process of assembling the rack and pinion type steering gear unit, both the ball bearing 16 and the seal ring 27a are externally fitted to the pinion shaft 6. When assembling multiple parts, the greater the number of parts to be assembled in one part, the more the assembly work can be consolidated and the cost can be reduced by increasing the efficiency of the assembly work. Costs can be reduced by increasing efficiency.

[Second Example of Embodiment]
FIG. 2 shows a second example of the embodiment of the present invention. In the case of this example, the seal ring 27a includes a stepped portion 33 formed on the outer peripheral surface of the intermediate portion of the pinion shaft 6, and a ring-shaped retaining ring 34 that is also locked in the locking groove on the outer peripheral surface of the intermediate portion. To prevent the seal ring 27a from coming off from the pinion shaft 6 more securely.
Since the configuration and operation of the other parts are the same as in the case of the first example of the above-described embodiment, the same parts are denoted by the same reference numerals, and redundant description is omitted.

The rack and pinion type steering gear unit of the present invention is a so-called column-type electric power unit in which an electric motor 36 or the like for applying auxiliary force is assembled to the steering column 35 as shown in FIG. It can also be implemented in combination with a steering device.
When the present invention is carried out, the stepped portion 33 in the intermediate portion of the pinion shaft 6 shown in FIGS. 1 and 2 may be omitted, and instead, a ring-shaped retaining ring may be locked to the portion. it can.

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 3 Universal joint 4 Intermediate shaft 5 Steering gear unit 6 Pinion shaft 7 Pinion tooth 8 Rack shaft 9 Rack tooth 10 Casing 11 Main storage part 12 Sub storage part 13 Spherical joint 14 Tie rod 15 Radial needle bearing 16 Ball bearing 17 Inner ring 18 Outer ring 19 Inner diameter side step surface 20 Conical retaining ring 21 Outer diameter side step surface 22, 22a Retaining screw cylinder 23 Cylinder cylinder part 24 Press block 25 Cover body 26 Spring 27, 27a Seal ring 28 Inward flange part 29 Male thread part 30 Tapered surface 31 Elastic material 32 Core metal 33 Stepped portion 34 Retaining ring 35 Steering column 36 Electric motor 37 Bellows

Claims (3)

  A casing having a cylindrical main storage portion open at both ends and a cylindrical sub storage portion provided at a twisted position with respect to the main storage portion and open at one end, and rack teeth on the front surface are provided. A rack shaft that is axially displaceable in the storage portion and a pinion tooth formed on the front half portion in the axial direction mesh with the rack teeth, and an axial base half portion of the auxiliary storage portion of the casing. Provided between the pinion shaft disposed in the sub-accommodating portion in a state of projecting outward from the opening, and the outer peripheral surface of the intermediate portion of the pinion shaft and the portion near the opening of the inner peripheral surface of the sub-accommodating portion. A bearing which rotatably supports the pinion shaft in the sub-accommodating portion, and an opening-side end portion of the inner peripheral surface of the sub-accommodating portion. This is a holding screw cylinder that holds down the stepped part In a rack and pinion type steering gear unit including a seal ring provided between an inner peripheral surface of a female screw cylinder and an intermediate outer peripheral surface of the pinion shaft, an inner peripheral surface of the set screw cylinder is The seal ring is a cylindrical surface that does not have a flange protruding radially inward, and the seal ring is formed by reinforcing a portion close to the inner diameter of an annular elastic material with an annular cored bar, and is provided at an intermediate portion of the pinion shaft. A rack-and-pinion type steering gear unit, wherein the outer peripheral edge of the elastic member is slidably contacted with the inner peripheral surface of the holding screw cylinder over the entire periphery in a state where it is externally fitted and fixed.   The bearing is a single-row ball bearing, and the inner ring constituting the ball bearing is externally fitted and fixed to the axially intermediate portion of the pinion shaft in a state of preventing axial displacement. The pinion shaft is clamped between the stepped portion and the holding screw cylinder, and is fitted and fixed in the sub-accommodating portion in a state of preventing the axial displacement of the pinion shaft. A second step portion is formed in a portion closer to the opening of the sub-accommodating portion than a portion where the inner ring is externally fitted, and the seal ring projects a portion closer to the inner diameter of one axial surface to the second step portion. The rack and pinion type steering gear unit according to claim 1, wherein the rack and pinion type steering gear unit is fitted and fixed to the pinion shaft in a state of being applied.   The outer diameter of the holding screw cylinder is smaller at the tip half projecting out of the sub-accommodating part than the base half part screwed into the opening end of the sub-accommodating part, and the outer peripheral edge of the seal ring Is a rack-and-pinion steering gear unit according to any one of claims 1 and 2, which is in sliding contact with the inner peripheral surface of the front half.

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