JPH10338156A - Sealing structure of center take-off type gear housing on steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent intrusion of water into the inside of a dust boot and the inside of a gear housing by interposing a washer to be engaged with a bolt for tie rod installation between the dust boot to cover a gear housing and a pair of the left and right tie rods and baking a synthetic resin made lip on an inner peripheral edge of this washer. SOLUTION: Inner edges of a pair of left and right tie rods 11, 12 are connected to a guide shoe 13 by bolts 15, 16, and a screw part of a head end of each of the bolts 15, 16 is screwed and fixed on a rack 4. Thereafter, a wheel is steered through the guide shoe 13 and the tie rods 11, 12 by engaging the rack 4 with a pinion and moving it left and right. A washer 19 is interposed between the dust boot 17 and inner ends of a pair of the left and right tie rods 11, 12 concerning sealing structure of a center take-off type gear housing 3 of such a steering device. A sealing property is improved by baking a lip 22 made of a synthetic resin elastic material to avoid intrusion of water by closely adhering on outer peripheral surfaces of the bolts 15, 16 on an inner peripheral edge of this washer 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal structure for a gear housing in a steering device such as a rack-and-pinion type electric power steering device used for a vehicle steering device. The inner ends of the tie rods are connected to the racks by bolts penetrating guide shoes that slide in long holes formed along the length direction of the gear housing, and the racks are guided by the guide shoes. This type of steering device moves left and right in accordance with the left and right movements, and a substantially central portion of a dust boot is penetrated by the bolt between the guide shoe and the inner ends of the pair of left and right tie rods. In the center take-off type gear housing, the inside of the dust boot and the inside of the gear housing To and be free of water ingress, their sealing structure.

[0002]

2. Description of the Related Art A center take-off type gear housing in a conventional rack-and-pinion type electric power steering apparatus is shown in FIG.
Tie rod 011 as shown in the intrusion paths A and B of FIG.
, 015, bolts 015, for attachment to the inner end of rack 04
016 and the tie rod 011
, 012, and water enters through the gap between the inner end of the washer 019 and the water, and the water further flows into the gap between the hole of the washer 019 and the outer peripheral surface of the bolt 015, 016, the inner peripheral surface of the collar 020 and the bolt 015. , 01
6 There is a possibility that the dust may enter the inside of the dust boot 017 or the inside of the gear housing 03 along the gap between the outer peripheral surface and the inside. 013 is a guide shoe.

In order to solve such a problem, Japanese Utility Model Application Laid-Open No. 59-85411 discloses a technique. This is illustrated in FIGS. 6 and 7. FIG. 6 is a longitudinal sectional view in a direction orthogonal to the longitudinal direction in FIG. 5, and portions corresponding to FIG. 5 are denoted by the same reference numerals.

In this case, as shown in these figures, a cylindrical seal member is provided on the inner peripheral surface of a hole of a washer 019.
One end of the seal member 030 is joined to form a bulging projection 031 on the outer periphery of the other end of the sealing member 030.
9, a gap 032 is formed between the dust boot 017 and the bolt penetrating portion.

In the bolt holes at the inner ends of the tie rods 011 and 012, a collar 033 is interposed between the outer surfaces of the bolts 015 and 016.
011 and 012 are sandwiched between a common washer 018 and a washer 019 arranged on both sides in the bolt hole direction of the inner end.

However, also in this case, the inner wall surface of the seal member 030 joined to the washer 019 has bolts 015, 016.
Since it is not structured so as to be in intimate contact with the outer surface of the water, it is not possible to sufficiently prevent water from entering in the same direction as the intrusion routes A and B.

In addition, the seal member 030 must be formed to a predetermined size, and when the seal member 030 formed to the predetermined size is joined to the inner peripheral surface of the hole of the washer 019, the seal member 030 is formed. The pinching gap 032 of the member 030 is not always properly secured, a manufacturing error occurs, and even if the pinching gap 032 is properly secured, the dust boot
It takes time and effort to stop the bolt penetration part of 017, which lowers the work efficiency.

When the bolt penetration portion of the dust boot 017 is not accurately stopped in the pinching gap 032, as shown in FIGS. 8 and 9, the dust boot 017 and the washer 019,
A gap is formed between the dust boot 017 and the seal member 030, and water enters into the dust boot 017 and eventually into the gear housing 03 from these gaps, thereby reducing the durability of the dust boot 017 and the electric power steering. There is a risk of causing a failure of the device.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a seal structure for a gear housing of a steering device which solves the above-mentioned problems. The inner end of the tie rod
Each of the gear housings is connected to the rack by a bolt penetrating a guide shoe that slides in a long hole formed along the length direction of the gear housing. A center take-off type gear housing seal in a steering device, wherein a substantially central portion of a dust boot is penetrated and held by the bolt between the guide shoe and the inner ends of the pair of left and right tie rods. In the structure, a washer is interposed between the dust boot and the inner ends of the pair of left and right tie rods, and at an inner peripheral edge of the washer,
A seal structure for a center take-off type gear housing in a steering device, wherein a lip made of a synthetic resin elastic material which is in close contact with the outer peripheral surface of the bolt and prevents water from entering is baked.

Since the invention described in claim 1 is constructed as described above, it has a simple structure in which a lip made of an elastic material made of a synthetic resin is baked on the inner peripheral edge of the washer, so that the tie rod side can be used. Water can be prevented from entering the inside of the dust boot and the inside of the gear housing via the washer. This improves the durability of the center take-off type gear housing in the steering device,
The reliability of the steering device can be improved.

According to the second aspect of the present invention, the adhesion between the lip and the outer peripheral surface of the bolt is increased, and the lip and the protruding end surface of the collar are also in close contact. Water can be further prevented from entering the inside of the dust boot or the inside of the gear housing from the tie rod side and around the washer. Thus, the durability of the center take-off type gear housing in the steering device and the reliability of the steering device can be further improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, one embodiment of the invention described in claims 1 and 2 of the present application shown in FIGS. 1 to 4 will be described. FIG. 1 is a partially cutaway view of a gear housing structure of a rack-and-pinion type electric power steering device according to the present embodiment. The gear housing structure is called a center take-off gear housing structure. The tie rod has an inner end attached to the rack at a substantially central portion in the longitudinal direction of the gear housing. FIG. 2 is a partially cutaway view of a gear housing structure of a rack and pinion type electric power steering apparatus from which an electric motor and a gear box are removed, and FIG. 3 is an enlarged view of a portion A in FIG. 4 is a longitudinal sectional view of the washer.

In these figures, a rack-and-pinion type electric power steering apparatus 1 has a gear housing 3 in which a rack 4 meshing with a pinion mounted on an input shaft 2 connected to a steering wheel (not shown) is mounted in a gear housing 3. The gear housing 3 is provided with mount portions 5 and 6 having bolt holes for mounting the vehicle body at both ends thereof. Then, a steering assist force corresponding to the vehicle speed is input to the input shaft 2 from the electric motor 7.

The gear housing 3 includes a left and right mount 5,
6 near the right end, and the left gear housing portion 3 of the split gear housing 3
Although not shown in detail, the outer peripheral surface of the left gear housing portion 3a and the inner peripheral surface of the right gear housing portion 3b are not shown in detail. In addition, a screw is formed, and a screw joint 23 in which a screw meshing with the two screws is formed on the inner and outer peripheral surfaces is interposed between the two screws.

The screw joint 23 is for adjusting the mounting position of the left and right gear housing portions 3a and 3b. If the screw joint 23 is turned while holding its head, the mounting position of the screw joint 23 is changed. It can be adjusted, and the left and right mounting parts 5,
The vehicle body mounting pitch t between the six can be easily adjusted to match the vehicle body.

A guide shoe 13 for guiding the movement of the inner ends of the pair of left and right tie rods 11 and 12 is provided along the length of the gear housing 3 and over the center of the gear housing 3.
A notch groove (elongated hole) 14 which can move left and right is formed over a predetermined length.

The inner ends of the pair of left and right tie rods 11, 12 are:
The two bolts 15 and 16 are connected to the guide shoe 13, and the threaded portions at the tips of the two bolts 15 and 16 are screwed into corresponding screw holes of the rack 4, and the rack 4 is connected to the pinion. When the guide shoe 13 and the tie rods 11 and 12 move left and right according to the left and right movement, the left and right wheels are steered through the outer ends of the tie rods 11 and 12. I have.

A guide shoe 13 and a pair of left and right tie rods 1
A central portion of a dust boot 17 covering a main portion of the gear housing 3 is sandwiched between the inner ends of 1 and 12 by bolts 15 and 16 and collars 20 and 20 described later, The left and right halves of the dust boot 17 are tie rod 1
It can be expanded and contracted according to the left and right movement of 1, 12.

Furthermore, tie rods 11 and 12, dust boots
When integrally connecting the guide shoe 13 and the rack 4 with the bolts 15 and 16, a common washer 18 is provided on one side of the inner ends of the tie rods 11 and 12, and a right and left dust boot 17 is provided between the other side and the dust boot 17 on the other side. Individual washers 19, 19 are interposed, and dust boots 1
7. Two collars 20, 20 on the left and right sides are straddled by the guide shoes 13, and the rack 4, and are penetrated by bolts 15, 16 and interposed. The collars 20, 20 penetrate the dust boot 17 and are slightly protruded toward the washer 19 side and are interposed.

FIG. 3 shows the detailed structure of the interposed portion of the washer 19. The figure shows a detailed structure of a corresponding portion on the tie rod 11 side, but the same applies to the tie rod 12 side. An annular projecting wall 21 for receiving a washer 19 is formed around a portion where the dust boot 17 is penetrated by the bolt 15 and the collar 20. The top surface of the projecting wall 21 is formed flat.

The washer 19 is interposed between the inner end of the tie rod 11 and the dust boot 17, and the bolt 15 is screwed to the rack 4 to be firmly held therebetween. Note that a seat 24 is preferably seated on the inner end of the tie rod 11 on the side of the washer 19, as shown in the figure. By doing so, the lip which is printed on the inner peripheral edge of the washer 19 described later
Since you will be able to receive 22 in a stationary state,
The durability of the lip 22 is improved.

At the inner end of the tie rod 11, two types of iron bushes 25, 26 are interposed between the bolt hole and the bolt 15, and both outer side surfaces of the larger diameter bush 25 are The tie rod 11 projects slightly outward from the bolt hole, and is tapered so that the axial interval on the inner peripheral surface side is longer than the axial interval on the outer peripheral surface side. Both side surfaces of the smaller bush 26 are formed as flat surfaces connected to the tapered ends of both side surfaces of the bush 25. And these flat surfaces are the common washer.
It comes in contact with 18, washer 19 or seat 24.

On the inner peripheral edge of the washer 19, a lip 22 made of a synthetic resin elastic material such as nitrile rubber having high elasticity, heat resistance and corrosion resistance is baked (see FIGS. 3 and 4). ). The lip 22 has the washer 19 interposed between the inner ends of the tie rods 11 and 12 and the dust boot 17 as described above, and is firmly clamped between the dust boots 17 by tightening the bolts 15 and 16. When the bush 26 is inserted into the bolt holes at the inner ends of the tie rods 11 and 12,
And the front end surfaces of the collars 20, 20 protruding through the dust boot 17, and are likely to spread in the plane direction of the washer 19, so that they are strongly adhered to the outer peripheral surfaces of the bolts 15, 16.

In this embodiment, since the lip 22 made of a synthetic resin elastic material is simply baked on the inner peripheral edge of the washer 19, the inner space of the dust boot 17, In addition, water that tends to enter the gear housing 3 can be effectively prevented.

That is, since the lip 22 is made of a synthetic resin elastic material and has a high elasticity, the washer 19 is attached to the tie rod 1.
When it is interposed between the inner ends of the dust boots 1 and 12 and firmly clamped, the flat surface or seat 2 of the bush 26 interposed in the bolt holes at the inner ends of the tie rods 11 and 12
4. Strongly adhere to the outer peripheral surfaces of bolts 15 and 16.

Therefore, water (water in the direction A) which has penetrated the gap between the bolt end portions of the inner ends of the tie rods 11 and 12 and the bolt outer surface in the bolt axis direction, and the inner ends and the washers 19
Water that has penetrated from the gap with the surface of the surface (water in the B direction)
The seal is effectively sealed by the close contact between the lip 22 and these surfaces, and is prevented from entering the interior space of the dust boot 17 and further into the gear housing 3. Thus, the durability of the center take-off type gear housing in the steering device is improved, and the reliability of the steering device is improved.

The collar 20 interposed across the rack 4, the guide shoe 13, and the dust boot 17 has one end surface protruding through the dust boot 17, and the inner peripheral edge of the washer 19. Lip 22, the lip 22 tends to spread further in the planar direction, and the adhesion between the lip 22 and the outer peripheral surfaces of the bolts 15 and 16 increases. Therefore,
Intrusion water from the A and B directions can be more effectively prevented.

Also, the close contact between the protruding end face of the collar 20 and the lip 22 and the contact between the annular protruding wall 21 formed on the dust boot 17 and the washer 19 as described above, along the back surface of the washer 19. Water that tries to enter the gap between the hole in the collar 20 and the outer surface of the bolt is double sealed. Therefore, the intrusion of water into the interior space of the dust boot 17 and further into the gear housing 3 is further prevented.

Further, in the present embodiment, the lip 22 baked on the inner peripheral edge of the washer 19 is structured so as to maintain the inner peripheral edge of the hole of the dust boot 17 penetrated by the bolts 15, 16 or the collar 20 in a liquid-tight manner. Washer, so washer
The structure of 19 becomes simple. Also, their assembly becomes easy.

In the present embodiment, the water that enters from the back of the washer 19 is sealed by the contact between the annular protruding wall 21 of the dust boot 17 and the washer 19, but the dust boot 17, the annular protruding wall 21, and the washer are sealed. The seal may be further strengthened by, for example, interposing an O-ring in the space formed by the seal 19.

In the embodiment described above, the steering device is an electric power steering device. However, the invention of the present application can be suitably applied to a hydraulic power steering device.

[Brief description of the drawings]

FIG. 1 is a partially cutaway view showing a gear housing structure of a rack and pinion type electric power steering apparatus according to an embodiment of the present invention described in claims 1 and 2 of the present application.

FIG. 2 is a diagram showing the gear housing structure of the rack and pinion type electric power steering device in which the electric motor and the gear box portion are removed in the embodiment of FIG.

FIG. 3 is an enlarged view of a portion A in FIG. 2;

FIG. 4 is a longitudinal sectional view of a washer in the embodiment of FIG.

FIG. 5 is a diagram showing a conventional example.

FIG. 6 is a diagram showing another conventional example.

7 is a longitudinal sectional view of a washer in the conventional example of FIG.

FIG. 8 is a diagram for explaining a problem in the conventional example of FIG. 6;

FIG. 9 is a diagram for explaining another problem in the conventional example of FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rack and pinion type electric power steering device, 2 ... Input shaft, 3 ... Gear housing, 3a ... Left gear housing part, 3b ... Right gear housing part, 4 ... Rack, 5, 6 ... Mounting part , 7 ... Electric motor, 11,12 ... Tie rod, 13 ... Guide shoe, 14 ... Notch groove (long hole), 15,16 ... Bolt, 17 ... Dust boot, 18
... common washer, 19 ... washer, 20 ... collar, 21 ... annular protruding wall, 22
... lip, 23 ... screw joint, 24 ... seat, 25, 26 ... bush.

Claims (2)

[Claims] An inner end of a pair of left and right tie rods is connected to a rack by a bolt penetrating a guide shoe that slides in an elongated hole formed along the length of the gear housing. While being guided by the shoe, the rack moves left and right according to the left and right movement of the rack, and a substantially central portion of the dust boot is penetrated by the bolt between the guide shoe and the inner ends of the pair of left and right tie rods. In the seal structure of the center take-off type gear housing in the steering device, the washer is interposed between the dust boot and the inner ends of the pair of left and right tie rods. A steering device characterized in that a lip made of a synthetic resin elastic material which is in close contact with the outer peripheral surface of the bolt to prevent water from entering is baked. Seal structure of the center take-off type gear housing in. 2. A collar is interposed across the rack, the guide shoe, and the dust boot, and the collar is penetrated by the bolt, and one end surface of the collar is connected to the dust boot. 2. A seal structure for a center take-off type gear housing in a steering apparatus according to claim 1, wherein the seal structure is formed so as to penetrate and protrude so as to be in close contact with a lip on an inner peripheral edge of the washer.