JP2000062627A - Power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the deformation of the lateral hole of a housing at the pressing time of a cylinder in the housing. SOLUTION: In this power steering device, a contact part 5p for catching a press-in load is provided on one part of the periphery direction of the end 5e of a housing 5 and contacted with the end surface 4c of a cylinder 4. The contact part 5p is shifted to the periphery direction of the lateral hole 5a for a support yoke and connected to the ribs 5v, 5w, 5x of the housing 5. The lateral hole 5a is not deformed by a press-in load. A step difference type receiver is provided on the inner periphery surface 5c of the housing 5. As the receiver stays on the cylinder side than the lateral hole 5a and catchs the press-in load by the contact to the jig for press-in at the assembly time, the deformation of the latersal hole 5b is prevented. Thereby, the contact part 5p prevents the relative displacement between the cylinder and housing at the overload time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering system for an automobile.

[0002]

2. Description of the Related Art In a rack and pinion type steering device, there is a power steering device which assists a force for moving a rack shaft by hydraulic pressure. In this power steering apparatus, the rack shaft is inserted into a steel cylinder that constitutes the rack housing and reaches the inside of a tubular housing made of cast aluminum that is connected to the cylinder. One of the opposing ends of the housing and the cylinder is press fit into the other. Positioning in the press-fitting direction is performed by the annular positioning abutting surfaces provided on the ends of the housing abutting the end faces of the cylinders facing each other over the entire circumference. An oil chamber accommodating a piston provided on the rack shaft is defined in a part of the cylinder to form a power cylinder.

The housing also accommodates a pinion that meshes with the rack shaft. In order to apply a pressure to the meshing portion between the pinion and the rack shaft, a support yoke urges the rack shaft from the opposite side of the pinion across the rack shaft. The support yoke is held in a lateral hole formed on the peripheral side surface of the housing. This lateral hole is processed with high precision in advance before press fitting the housing and the cylinder.

[0004]

By the way, since the lateral hole is on the peripheral side surface of the housing, it is easily deformed when an axial force is applied. As a result, the lateral hole may not be maintained with high dimensional accuracy when the cylinder is press-fitted into the housing.
In particular, when the end surface of the cylinder and the contact surface of the housing are brought into contact with each other as described above, the press-fitting load tends to be large, so that the lateral holes are more likely to be deformed.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above technical problems and to provide a power steering apparatus in which a lateral hole of a housing is not deformed when a cylinder is press-fitted into the housing.

[0006]

As a means for achieving the above object, the aspect of the present invention as set forth in claim 1 accommodates an end portion of a cylinder through which a rack shaft is inserted and a pinion which meshes with the rack shaft. And an end portion of a cylindrical housing that is fitted with each other by press fitting, and the housing has a lateral hole through which means for applying a pressure to the meshing portion of the rack shaft and the pinion is inserted through the rack shaft. In the power steering apparatus, at least one of the cylinder and the end portion of the housing has a contact portion in a circumferential direction that abuts on the other side and positions in the press-fitting direction. It is characterized in that it is offset from the lateral hole in terms of direction.

According to this aspect, at the time of press-fitting in the assembling process, the contact portion located at a position displaced from the lateral hole comes into contact with the other party to receive the press-fitting load. As a result, the deformation of the lateral holes can be suppressed. The aspect of the invention described in claim 2 is
In claim 1, the housing includes a rib that is continuous with the contact portion and can receive a press-fitting load when press-fitting into the cylinder.

According to this aspect, since the press-fitting load is reliably received mainly by the ribs, the lateral holes are less likely to be loaded, and as a result, the deformation of the lateral holes can be further suppressed. According to a third aspect of the present invention, an end portion of a cylinder into which the rack shaft is inserted and an end portion of a tubular housing that houses a pinion that meshes with the rack shaft are fitted to each other by press fitting. In a power steering apparatus having a lateral hole through which means for applying a pressure to the meshing portion of the rack shaft and the pinion is inserted through the rack shaft, the power steering apparatus is introduced into the housing at the inner periphery of the housing at the time of press fitting. The receiving portion that abuts the press-fitting jig and receives the press-fitting load is provided on the cylinder side of the lateral hole.

For example, the receiving portion may be a step or slope formed on the inner circumference of the housing. Further, as the press-fitting jig, a rod-shaped member can be used in which one end is in contact with the receiving portion and the other end extends beyond the inlet of the inner circumference of the housing. During the assembly process, the press-fitting jig is introduced into the housing, brought into contact with the receiving portion of the housing, and in this state, the cylinder is press-fitted into the housing.

According to this aspect, since the press-fitting load is received by the receiving portion, the press-fitting load is not applied to the lateral hole, and as a result, the deformation of the lateral hole can be prevented.

[0011]

DETAILED DESCRIPTION OF THE INVENTION A power steering apparatus according to an embodiment of the present invention will be described below with reference to the accompanying drawings. Figure 1
FIG. 1 is a front sectional view of a power steering apparatus showing a first embodiment of the present invention. The power steering apparatus 1 is configured such that the force for moving the rack shaft 3 of the rack and pinion steering apparatus is assisted by hydraulic pressure.

The power steering apparatus 1 includes a pinion 2 which rotates in association with a handle (not shown), and the pinion 2.
A cylindrical rack shaft 3 having a rack 3a that meshes with a part of its peripheral surface, a cylinder 4 that constitutes a rack housing that surrounds the rack shaft 3, and a pinion 2 that is connected to the cylinder 4 and that houses the pinion 2 It has a tubular housing 5. The rack shaft 3 is inserted through the housing 5 and the cylinder 4. Steering wheels (not shown) are connected to the ends of the rack shaft 3 via ball joints 6 and the like.

When the handle is operated, the pinion 2 rotates, and the rack shaft 3 meshing with the pinion 2 moves in the axial direction. Thereby, the steered wheels can be steered. Further, in the power steering apparatus 1, the oil chamber 22 that accommodates the piston 21 provided on the rack shaft 3 is provided in a part of the cylinder 4.
And a power cylinder 20 for steering assistance that assists the movement of the rack shaft 3 in the axial direction.

That is, a center bush 23 having a rack shaft 3 slidably inserted therein is mounted inside one end 4a of the cylinder 4, and in the vicinity thereof, a space between the cylinder 4 and the rack shaft 3 is provided. It is sealed by a rack seal 24. The rack shaft 3 is slidably inserted into the other end 4b of the cylinder 4 to form an end cover 2.
5 is mounted, and in the vicinity thereof, a rack seal 26 seals between the cylinder 4 and the rack shaft 3. An oil chamber 22 is defined between the center bush 23 and the end cover 25, and the piston 21 is integrally mounted on the rack shaft 3 in the oil chamber 22 and slidably fitted in the cylinder 4. There is. The piston 21 divides the oil chamber 22 into two parts 22a and 22b. By supplying pressure oil to the parts 22a and 22b partitioned from each other according to the steering direction and the steering resistance, a steering assist force is obtained.

Further, in the housing 5, means 30 for applying a pressure to the meshing portion of the rack shaft 3 and the pinion 2 via the rack shaft 3 is provided. That is, the support yoke 31 biases the rack shaft 3 toward the pinion 2. The support yoke 31 is arranged on the opposite side of the pinion 2 with the rack shaft 3 interposed therebetween, and is held in a lateral hole 5 a formed in the peripheral side surface of the housing 5. This lateral hole 5a
Inside the support yoke 3 in order from the rack shaft 3 side.
1, a spring 32 and an adjusting member 33 are arranged. The adjusting member 33 is screwed into the lateral hole 5a to close it. The spring 32 includes an adjusting member 33 and a support yoke 31.
It is sandwiched between and to press the support yoke 31. The support yoke 31 is movable in the lateral hole 5a in the extending direction of the lateral hole 5a, and presses the rack shaft 3 against the pinion 2 by the elastic force of the spring 32. The pressing force can be adjusted by adjusting the screwing amount of the adjusting member 33 into the housing 5.

FIG. 2 is a partial sectional front view showing only the housing 5 and the cylinder 4 of FIG. Housing 5
Is a cast part made of aluminum alloy. The housing 5 is formed in a tubular shape, and the rack shaft 3 is inserted through the inside thereof. In the following, the directions will be described based on the axial direction, the radial direction, and the circumferential direction of the cylindrical rack shaft 3.

The housing 5 has a main cylindrical portion 5g extending along the rack shaft 3, a first sub-cylindrical portion 5h projecting from the outer peripheral surface of the main cylindrical portion 5g orthogonally to the axial direction, and an axial direction from the outer peripheral surface. It has two second sub-cylindrical portions 5i that obliquely intersect and project. The above-mentioned lateral hole 5a for the support yoke 31 is defined in the first sub-cylindrical portion 5h. Each second sub-cylinder portion 5i
Further, an inclined hole 5b for pinion for rotatably supporting the pinion 2 is defined. The two second sub-cylindrical portions 5i are
Main cylinder part 5g so that each oblique hole 5b is in a straight line
From each other in opposite directions. Side holes 5a and 2
The main cylindrical portion 5g is formed so that the two oblique holes 5b intersect with each other.
Communicates with the inside of.

The main cylinder portion 5g of the housing 5 has an end portion 5a.
The press-fitting fitting surface 5j composed of the outer peripheral surface at e, and the annular flange portion 5k provided adjacent to the press-fitting fitting surface 5j.
And an annular protrusion 5m parallel to the flange 5k, an annular protrusion 5n near the end 5f, and a plurality of ribs 5s, 5t, 5u, 5v, 5w, 5x along the outer peripheral surface of the main tubular portion 5g. ，
It has 5y and 5z. The inner peripheral surface of the end portion 4a of the cylinder 4 is axially press-fitted into the press-fitting fitting surface 5j.

The ribs 5s, 5t, 5u are formed so as to extend parallel to the axial direction, are arranged at substantially the same positions in the circumferential direction, and are continuous with each other. That is, the rib 5s
Connects the flange portion 5k and the annular convex portion 5m to each other to form the rib 5
t connects the annular convex portion 5m and the peripheral surface of the first sub-cylindrical portion 5h near the end portion 5e, and the rib 5u defines the end portion 5 of the first sub-cylindrical portion 5h.
The peripheral surface close to f is connected to the annular convex portion 5n.

The ribs 5v, 5w, 5x are formed at positions different from the above-mentioned ribs 5s, 5t, 5u in the circumferential direction,
They are connected to each other. That is, the rib 5v connects the flange portion 5k and the annular convex portion 5m and extends parallel to the axial direction. The rib 5w connects the annular convex portion 5m and the peripheral surface of the second sub-cylindrical portion 5i near the end 5e, and extends in a direction inclined with respect to the axial direction. The rib 5x is an end 5f of the second sub-cylindrical portion 5i.
The peripheral surface on the side and the annular convex portion 5n are connected to each other and extend in a direction inclined with respect to the axial direction. The rib 5w and the rib 5x are inclined in opposite directions, and the connecting portion between the rib 5w and the annular convex portion 5m and the connecting portion between the rib 5x and the annular convex portion 5n are arranged at substantially the same position in the circumferential direction. Has been done. In addition, the rib 5v and the rib 5w are connected at the same position in the circumferential direction via the annular convex portion 5m. Although not shown, these ribs 5
v, 5w, 5x correspond to the two second sub-cylindrical parts 5i,
Two sets are provided.

The rib 5y connects the peripheral surface near the end 5f where the second sub-cylindrical portions 5i are connected to the annular convex portion 5n, and the rib 5z connects the second sub-cylindrical portions 5i to each other. The peripheral surface close to the annular convex portion 5m is connected to the annular convex portion 5m. The rib 5y is provided on the opposite side in the radial direction of the rib 5u, and the rib 5z is provided on the opposite side in the radial direction of the rib 5t.

Further, the end portion 5e of the housing 5 has a contact portion 5p which comes into contact with the end surface 4c of the counterpart cylinder 4 to perform axial positioning in the press-fitting direction. The contact portion 5p is formed between the press-fitting fitting surface 5j and the flange portion 5k. In this way, the end surface 4c of the cylinder 4
Is positioned in the press-fitting direction by the abutting portion 5p of the end 5e of the housing 5, so that the relative displacement between the cylinder 4 and the housing 5 that occurs when the pinion 2 is overloaded can be reliably prevented. .

By the way, the above-mentioned positioning in the press-fitting direction is
When the end surface 4c of the cylinder 4 and the contact portion 5p of the housing 5 are brought into contact with each other, the press-fitting load at the time of assembly tends to be large, so that the above-mentioned lateral hole 5a for the support yoke is deformed. Is assumed. In particular, in the case of the combination of the steel cylinder 4 and the aluminum housing 5, the lateral hole 5a is likely to be deformed.

On the other hand, in the first embodiment of the present invention, as shown in the partial sectional side view of the housing 5 shown in FIG. With respect to the circumferential direction of the housing 5, it is displaced from the lateral hole 5a for the support yoke. Thereby, the deformation of the lateral hole 5a can be prevented. The contact portion 5p is formed by bulging the cylinder-side surface of the flange portion 5k of the main cylinder portion 5g in the axial direction, and is formed at a plurality of locations, for example, two locations. A recessed escape portion 5q for avoiding contact with the end surface 4c of the cylinder 4 is formed on the surface of the flange portion 5k on the cylinder side between the contact portions 5p. The escape portion 5q is larger in the circumferential direction than the contact portion 5p. When viewed in the axial direction of the rack shaft 3, the escape portion 5q and the lateral hole 5a overlap each other, and the contact portion 5p and the lateral hole 5a do not overlap each other. The contact portions 5p are arranged at positions symmetrical to each other with respect to the center of the housing 5. Also,
With respect to the circumferential direction, a lateral hole 5a is arranged at an intermediate position between the two contact portions 5p along the outer peripheral surface of the main tubular portion 5g.

The contact portion 5p is, as shown in FIG.
The ribs 5v are arranged in the circumferential direction so as to coincide with each other with the flange 5k interposed therebetween, and are connected to the ribs 5v via the flanges 5k. The ribs 5v are connected to the ribs 5w via the annular protrusions 5m. The rib 5 is provided via the second sub-cylindrical portion 5i.
It connects with x, and connects from the annular convex part 5n to the end part 5f. In this way, the ribs 5v, 5w, 5x are connected to the abutting portion 5p so as to be able to receive the load in the axial direction, so that most of the press-fitting load with the cylinder 4 during assembly can be received. Yes, housing 5 against this press-fit load
Can be reinforced.

On the other hand, the escape portion 5q is arranged at a position facing the lateral hole 5a in the circumferential direction. As a result, it is possible to prevent the press-fitting load from being applied to the lateral hole 5a during assembly. Further, the ribs 5s, 5t, and 5u do not receive the press-fitting load so much, but the housing 5, particularly the first rib
Reinforcement is performed around the sub-cylindrical portion 5h.

As described above, according to this embodiment, at the time of press-fitting in the assembling process, the abutting portion 5p located at a position displaced from the lateral hole 5a abuts the end surface 4c of the end portion 4a of the counterpart cylinder 4. The press-fitting load. As a result, the deformation of the lateral holes 5a can be suppressed, and the lateral holes 5a can be maintained with high dimensional accuracy. Therefore, it is possible to prevent defective products having low dimensional accuracy from occurring during assembly, and thus it is possible to reduce manufacturing costs.

Thus, the support yoke 31 can be manufactured at low cost.
Since the gap between the horizontal hole 5a and the lateral hole 5a can be appropriately secured, an appropriate pressurization can be applied to the rack shaft 3. As a result, the torque for steering operation does not become large, and the play of the steering wheel is excessive. It can be prevented from becoming too large. Further, since the press-fitting load is reliably received mainly by the ribs 5v, 5w, 5x, it becomes more difficult to load the lateral holes 5a for the support yoke, and as a result, the deformation of the lateral holes 5a can be further suppressed. it can.

The contact portion 5p is not limited to the above-mentioned structure. For example, a part of the end surface 4c of the cylinder 4 is provided so as to project in the axial direction, and an abutting portion that abuts on the other side to position in the press-fitting direction is provided to the abutting portion and the flange portion 5k of the housing 5. May abut. Further, both the cylinder 4 and the housing 5 may be provided with a contact portion. In short, at least one of the end portion 4a of the cylinder 4 and the end portion 5e of the housing 5 is brought into contact with the other party to position in the press-fitting direction. It suffices to have a contact portion that

The structure of the ribs is not limited to the above-mentioned one, and the point is that a rib connected to the contact portion 5p and capable of receiving a press-fitting load at the time of assembly may be provided. Next, a second embodiment will be described. FIG. 4 is a partial cross-sectional front view of the housing and the cylinder of the power steering apparatus 1 according to the second embodiment of the present invention. In the second embodiment, on the inner peripheral surface 5c of the housing 5, the receiving portion 5r that abuts the press-fitting jig G (see FIG. 5) introduced into the housing 5 during press-fitting and receives the press-fitting load is It is provided closer to the cylinder 4 than the hole 5a.

The receiving portion 5r has a lateral hole 5a in the axial direction.
And the contact portion 5p. The receiving portion 5r is
It is a step formed on the inner peripheral surface 5c. A portion of the inner peripheral surface 5c on the cylinder 4 side is formed relatively thin, and a step is formed at a connecting portion between a portion having a large inner diameter and a portion having a small inner diameter. This step is formed so as to be able to contact the press-fitting jig G introduced from the end 5f side of the housing 5. The receiving portion 5r is formed in an annular shape, contacts the press-fitting jig G over the entire circumference, and receives a load.

The inner peripheral surface 5c is formed so that the press-fitting jig G can be guided and can be guided to the receiving portion 5r. Further, the portion of the inner peripheral surface 5c of the end portion 5f and the outer peripheral surface of the press-fitting jig G facing this portion are fitted to each other,
The centers of the press-fitting jig G and the inner peripheral surface 5c of the housing 5 can be aligned with each other. As a result, the press-fitting jig G can be reliably attached to the receiving portion 5r of the housing 5.

The contact portion 5p is formed in an annular shape so as to be able to contact the end surface 4c of the cylinder 4 over the entire circumference, and the relief portion 5q of the first embodiment is not provided. Press-fitting jig G
For example, a rod-shaped member having a length in which one end is in contact with the receiving portion 5r and the other end extends beyond the inside on the other end side of the housing 5 can be used. FIG. 5 illustrates a state in which the press-fitting jig G is erected on the worktable T.

During the assembling process, as shown in FIG. 5, the press-fitting jig G is introduced into the housing 5 from the end 5f side and brought into contact with the receiving portion 5r of the housing 5, and in this state, the cylinder 4 The end 4a of the above may be press-fitted into the press-fitting fitting surface 5j of the housing 5. As described above, according to the present embodiment,
By receiving the press-fitting load by the receiving portion 5r during assembly, the press-fitting load is not applied to the lateral holes 5a for the support yoke, and as a result, the deformation of the lateral holes 5a can be prevented. Therefore, the lateral hole 5a can be maintained with high dimensional accuracy,
As a result, the work for properly obtaining the gap between the lateral hole 5a and the support yoke 31 can be simplified.

Further, since the press-fitting jig G can be guided to the receiving portion 5r by the inner peripheral surface 5c of the housing 5, the press-fitting jig G can be easily attached to the housing 5, and the press-fitting jig G can be mounted.
Thereby, the housing 5 can be securely held from the inside. Further, since the inner peripheral surface 5c of the housing 5 can be used for holding by the press-fitting jig and easy mounting of the press-fitting jig,
The press-fitting jig can be simplified, and consequently the equipment cost for the press-fitting jig can be reduced.

Further, the present embodiment can be applied to the power steering apparatus 1 of the type in which the positioning of the cylinder 4 and the housing 5 at the time of press fitting is performed without the cylinder 4 and the housing 5 being brought into contact with each other. In this case, since the lateral hole 5a is not deformed, it is possible to press-fit with a larger press-fitting load, for example. In addition, the receiving portion 5r in the present embodiment
May be arranged closer to the cylinder 4 than the contact portion 5p. In short, it suffices if it is on the cylinder 4 side with respect to the support yoke lateral hole 5a.

The receiving portion 5r may be an inclined surface in addition to the step formed on the inner peripheral surface 5c. Also, the receiving portion 5r
May be provided at a plurality of positions in the circumferential direction. The point is that a portion capable of abutting the press-fitting jig G introduced into the housing 5 during press-fitting and receiving a press-fitting load may be provided. Further, the contact portion 5p of the housing 5 may be provided in a part in the circumferential direction as in the first embodiment, and the relief portion 5q may be provided.

Although the inner peripheral surface of the cylinder 4 is press-fitted into the outer peripheral surface of the housing 5 in each of the above-described embodiments, the outer peripheral surface of the cylinder 4 may be press-fitted into the inner peripheral surface of the housing 5. . In addition, various design changes can be made without changing the gist of the present invention.

[0039]

According to the invention described in claim 1, since the press-fitting load at the time of assembly is received by the abutting portion located at a position displaced from the lateral hole, the deformation of the lateral hole can be suppressed, and the dimension of the lateral hole. The accuracy can be reliably maintained. According to the invention described in claim 2, most of the press-fitting load can be reliably received by the abutting portion and the rib continuing to the abutting portion, and the deformation of the lateral hole can be further suppressed.

According to the third aspect of the present invention, the press-fitting load is received by the receiving portion on the inner circumference of the housing, so that the lateral hole is not loaded, and as a result, the deformation of the lateral hole can be prevented, and the dimension of the lateral hole can be prevented. The accuracy can be reliably maintained.

[Brief description of drawings]

FIG. 1 is a cross-sectional front view of a power steering apparatus showing a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional front view of the housing and cylinder of FIG.

3 is a partial cross-sectional side view of the housing showing the A cross section of FIG. 2. FIG.

FIG. 4 is a partial cross-sectional front view of a housing and a cylinder of a power steering apparatus according to a second embodiment of the present invention.

5 is a cross-sectional view showing an assembly of the housing and the cylinder of FIG.

[Explanation of symbols]

1 Power steering device 2 pinion 3 rack shafts 4 cylinders 4a end 4c End surface (other party) 5 housing 5a side hole 5e end 5p contact part 5r receiver 5v, 5w, 5x ribs 31 Support yoke (means for applying pressure) G Press-fitting jig

Continued front page    (72) Inventor Yuji Kusano             3-5-8 Minamisenba, Chuo-ku, Osaka Koyo             Within Seiko Co., Ltd. F-term (reference) 3D033 JB02

Claims (3)

[Claims] 1. An end of a cylinder through which a rack shaft is inserted,
The rack shaft and the end of a tubular housing that houses the pinion that meshes with each other are fitted into each other by press fitting, and the housing has a means for applying a pressure to the meshing portion of the rack shaft and the pinion through the rack shaft. In a power steering apparatus having a lateral hole, at least one of the cylinder and the end portion of the housing has a contact portion, which abuts on the other side and positions in the press-fitting direction, in a part of the circumferential direction. The power steering apparatus, wherein the contact portion is displaced from the lateral hole in the circumferential direction of the housing. 2. The power steering apparatus according to claim 1, wherein the housing includes ribs that are connected to the abutting portion and can receive a press-fitting load when the housing is press-fitted. 3. An end portion of a cylinder through which a rack shaft is inserted,
The rack shaft and the end of a tubular housing that houses the pinion that meshes with each other are fitted into each other by press fitting, and the housing has a means for applying a pressure to the meshing portion of the rack shaft and the pinion through the rack shaft. In a power steering apparatus having a lateral hole, a receiving portion, which abuts a press-fitting jig that is introduced into the housing at the time of press-fitting and receives a press-fitting load, is provided on the inner periphery of the housing closer to the cylinder than the lateral hole. A power steering device, characterized in that it is provided in the.