JPH04135874U - Power steering device - Google Patents

Abstract

(57) [Summary] [Purpose] In order to prevent damage due to contact with the rack teeth formed near one end of the rack shaft, the inner diameter of the support member is increased, which causes deflection of the rack shaft and a decrease in the shaft sealing function. To prevent. [Structure] The inner periphery of the support member 6 has a tapered surface whose diameter is gradually reduced in the direction in which the rack shaft 1 is inserted into the housing 2.
6b, and the auxiliary support member 10 is press-fitted therein. This auxiliary support member 10 has a tapered outer surface 10b and is formed in an annular shape with a split slit in the axial direction, and has an inner diameter larger than the inner diameter of the backup ring 9 before being press-fitted into the tapered surface 6b. When press-fitted into the tapered surface 6b, the inner diameter is smaller than the inner diameter of the backup ring 9.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to a hydraulic power steering device, more specifically, a rack and pinion type power steering device. A hydraulic cylinder for steering assistance is installed in the middle of the cylindrical housing that supports the rack shaft of the steering mechanism. The present invention relates to a power steering device comprising a steering wheel.

0002

[Conventional technology]

A hydraulic power steering device uses hydraulic pressure generated by a hydraulic cylinder placed in the steering mechanism. This assists with the force required to operate the steering wheel and provides a comfortable steering feel. In recent years, not only large vehicles such as trucks and buses, but also regular passenger cars and small They are also being installed in passenger cars. One such power steering device is a pinion that rotates in conjunction with the rotation of the steering wheel. A part of the pinion is meshed with the pinion, and the axial direction is the left and right direction of the vehicle body. The rack shaft is equipped with a rack shaft, and the rack shaft Rack and pinion type in which steering is performed by movement in the axial direction generated by There is a steering mechanism.

0003 Figure 5 shows how the rack shaft is supported in a conventional rack and pinion power steering device. 1 is a cross-sectional view showing the rack shaft, and in the figure, 1 indicates a rack shaft, and 2 indicates a housing. rack The shaft 1 is supported inside a cylindrical housing 2 so as to be slidable in the longitudinal direction of the shaft. The partially formed rack teeth 1a are attached to a pinion 3 that rotates in conjunction with a steering wheel (not shown). They are engaged near one end of the housing 2. Both ends of rack shaft 1 are housings. protruding outward from both ends of the ring 2 and through separate ball joints 11, 12. The left and right steering wheels are connected to tie rods 13 and 14, respectively, which control the rotation of the steering wheels. is a rack via the pinion 3 that interlocks with this and the rack tooth 1a that meshes with the pinion 3. This sliding movement is converted into sliding movement of the lock shaft 1, and this sliding movement is used to steer left and right by the tie rods 13 and 14. The signal is transmitted to the wheels, and the direction of the steering wheels is changed to perform steering.

0004 The rack shaft 1 is connected to a pinion by a support yoke 4 attached to a housing 2. A cylindrical member is pressed against the housing 3 and is fitted and fixed to the other end of the housing 2. The support member 5 further includes a housing located between the support yoke 4 and the support member 5. They are each supported by a cylindrical support member 6 that is fitted and fixed in the ring 2.

The reason why three-point support is provided by the support members 5 and 6 and the support yoke 4 is as follows. A reaction force F acts on the rack shaft 1 from the left and right steering wheels via tie rods 13 and 14 connected to both ends, and the deflection is caused by a component force F ₁ of this reaction force F in a direction perpendicular to the shaft length direction. The piston 15 fixed to the rack shaft 1 is eccentrically slid relative to the cylinder portion 17.

[0006] When the support member 6 has only a function as a sealing wall, that is, when the support member 6 and the If the gap between the piston 15 and the cylinder part 17 is large, there may be a large sliding gap between the piston 15 and the cylinder part 17. There is a risk that the dynamic resistance will cause localized abnormal wear on the seal ring 16, and the sealing performance will deteriorate. In addition to causing performance deterioration, when the oil pressure difference between both sides of the piston 15 is large, this oil pressure difference There is a risk that part of the seal ring 16 may fall off from its wrapped position due to Even in the case of misalignment, if sufficient steering assist force from the hydraulic cylinder cannot be obtained, This causes an inconvenience. The support member 6 supports the rack shaft 1 at the fixed position of the piston 15. This is to suppress the bending and prevent the above-mentioned inconvenience from occurring.

[0007] FIG. 6 is an enlarged half-cut view of the support member 6 and its vicinity, and shows the support in the support member 6. A shaft sealing member is installed with a backup ring 9 interposed on one side facing the member 5. 8 is provided in sliding contact with the outer peripheral surface of the rack shaft 1. Although the structure of the support member 5 and its vicinity is not specifically shown, the outer surface side of the support member 5 Similarly, a shaft sealing member 7 is provided in sliding contact with the outer peripheral surface of the rack shaft 1. And ha Inside the housing 2, there is a cylinder portion sealed on both sides by the supporting members 5 and 6. 17 is formed, and on the outer periphery of the rack shaft 1 located inside this cylinder part 17, a disc-shaped A hydraulic cylinder is constructed by providing a piston 15.

[0008] By the way, in the conventional power steering device as described above, the rack shaft 1 is placed inside the housing 2. In the case of supporting the support member 6 inside the housing 2, , a rack in which the piston 15 is fixedly installed from the opening at one end of the housing 2 (left side in the figure) Insert the shaft 1 into the support member 6 with the end on the side where the rack teeth 1a are formed first, and then Then insert the support member 5 into the opening while fitting it onto the other end of the rack shaft 1. At the same time, the pinion 3 is installed in a predetermined position on the housing 2, and the pinion 3 is attached to the housing 2. After engaging the rack teeth 1a, the support yoke 4 is attached and the rack shaft 1 is gripped. ing.

[0009] However, the support member 6 is located at a position away from the opening at one end of the housing as shown in the figure. Because it is fixed, when inserting the rack shaft 1 inside the housing 2, the rack teeth 1a The shaft sealing member 8 attached to the inner peripheral side of the supporting member 6 is damaged and the seal is damaged. Stopping performance may be impaired, and pressure oil inside the cylinder section 17 may leak to the outside after assembly. There was a risk that it would come out.

0010

[Problem that the idea aims to solve]

For this reason, normally there is a hole on the outer periphery of one end of the rack shaft 1 including the rack teeth 1a, as shown in FIG. With the protective sleeve 20 fitted on the outside and covering the rack teeth 1a, insert the rack shaft 1 into the housing 2. In such a case, the outer diameter of the rack shaft 1 is larger by the thickness of the protective sleeve 20, so the inner diameter of the support member 6 should also be adjusted accordingly. It is necessary to set it slightly larger. Therefore, the installation of rack axis 1 is completed. between the circumferential surface of the rack shaft 1 and the inner circumferential surface of the support member 6 and backup ring 9. The gap 6a formed in the rack increases, the amount of deflection of the rack shaft 1 increases, and the shaft seal There is a problem that the shaft sealing function of member 8 may be degraded and pressure oil may leak to the outside. It was. Consider reducing the diameter of the tip of the rack shaft 1 by the thickness of the protective sleeve 20. However, it is inevitable that the strength of the rack shaft 1 will decrease, and the number of machining steps will also increase. There is a difficulty in doing so.

[0011] This invention was made in view of such circumstances, and its purpose is to Provide a gap equivalent to the thickness of the protective sleeve formed between the lock shaft and the support member. Oil that has been reduced in size to reduce the amount of deflection of the rack shaft and improve the sealing function. The purpose of the present invention is to provide a pressure-type power steering device.

0012

[Means to solve the problem]

The power steering device according to the present invention has a rack shaft having rack teeth near one end. It is inserted into the inside of the shaped housing, and one end of the housing opposite to the rack teeth. supporting members disposed at the upper and middle portions, and at the meshing portion between the rack teeth and the pinion. The cylinder is supported at three points so as to be able to slide freely in the longitudinal direction of the shaft. A piston fixedly installed in the middle of the rack shaft is fitted into the section, and a hydraulic system for steering assistance is installed. In a rack and pinion type power steering device consisting of a cylinder, the housing The inner circumferential surface of the support member placed in the middle part has a guide for inserting the rack shaft into the cylindrical housing. A tapered surface that gradually decreases in diameter in the axial direction is provided, and inside this tapered surface, there is a at least one split slit, the outer circumferential surface of which is a tapered surface of the supporting member. is formed on a tapered surface corresponding to the rack shaft, and is fitted into the support member from the insertion direction of the rack shaft. It is characterized by the provision of an auxiliary support member whose inner diameter is reduced as the load is applied. shall be.

[0013]

[Effect]

In this invention, a slit is formed in the axial direction, and the outer peripheral surface is a tapered surface. Place the auxiliary support member in an annular shape on the inner side of the support member, and attach the latch to the housing 2. By fitting shallowly when inserting the support shaft, the inner diameter of the auxiliary support member can be tightened. When the rack axle has been inserted, , by inserting the auxiliary bearing member deeply into the bearing member, the auxiliary bearing member is slid. By reducing the circumferential length within the range of the cut width, the inner diameter is reduced and the bearing member, auxiliary bearing part This makes it possible to reduce the gap between the material and the rack shaft.

[0014]

【Example】

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof. Figure 1 is related to the present invention. FIG. 3 is a cross-sectional view showing how the rack shaft is supported in the power steering device. In the figure, 1 is a rack shaft, and 2 is a cylindrical housing. Rack axis 1 is A rack tooth 1a is formed near one end over an appropriate length in the axial direction. It is supported inside the housing 2 so as to be slidable in the axial direction, and both ends of the housing 2 are open. Both ends of the rack shaft 1, which protrudes an appropriate length from the mouth, are attached to separate ball joints. Connectors 11 and 12 are connected to tie rods 13 and 14, which are connected to left and right steering wheels (not shown), respectively. They are connected. Also, the area near the end of one side (right side in the figure) of the housing 2 is not shown. A pinion 3 connected to the steering wheel is supported rotatably around an axis that intersects the rack shaft 1. and is engaged with the rack teeth 1a.

[0015] The pinion 3 is connected to a steering wheel (not shown), and the rotation of the steering wheel is connected to this. The rack shaft is connected to the rack shaft through the rotating pinion 3 and the rack teeth 1a that mesh with the pinion 3. 1, and occurs in the axial direction of the housing 2, that is, in the left-right direction of the vehicle body. The sliding motion of the rack shaft 1 is transmitted to the left and right steering wheels by the tie rods 13 and 14, respectively. The direction of the steering wheel is changed to perform steering.

[0016] The housing 2 is slidable in a direction perpendicular to the axial direction thereof, and has an internal structure. The support yoke 4, which is biased toward the It is installed. At the position where the rack shaft 1 engages with the pinion 3, this support It is pressed against the pinion 3 by the arc 4 and supported in a manner that it is held between them. ing. Also, the housing 2 has a side opposite to the mounting position of the support yoke 4 (left side in the figure). and a cylindrical shape located between the end and the mounting position of the support yoke 4. The bearing members 5 and 6 are fixedly fitted inside the support member 5 and 6. In this state, the rack shaft 1 is supported at three points.

[0017] A shaft sealing member 7 such as an oil seal is provided on the inner periphery of the supporting member 5 on the outer side. A backup ring 9 is interposed on the side of the supporting member 6 facing the supporting member 5. A shaft sealing member 8 such as an oil seal is provided on the inner peripheral side of the supporting member 6. The auxiliary support member 10 is press-fitted into. Inside the housing 2 are the shaft sealing members 7, 8, etc. A cylinder part 17 is formed which is sealed on both sides, and the inside of this cylinder part 17 is A hydraulic cylinder is constructed by providing a disk-shaped piston 15 in the middle of the rack shaft 1 located at has been completed. The gap between the piston 15 and the inner peripheral surface of the cylinder part 17 is the same as that of the piston 15. It is sealed by a seal ring 16 wrapped around the outer circumference, and the piston 15 is sealed on both sides. The oil chamber has a known structure and is mounted midway through the shaft connecting the pinion 3 and the steering wheel. A hydraulic pump (not shown), which is a hydraulic pressure generation source, is connected via a rotary hydraulic control valve (not shown). They are connected to each other.

[0018] Figure 2 is an enlarged half-cut view of the vicinity including the support member 6, and Figure 3(a) is the side of the auxiliary support member. 3(b) is a front view, and FIG. 4 is an explanatory diagram of the operation. The support member 6 is formed into a short cylindrical shape, and the inner peripheral surface thereof has a back-up ring 9 side. The inner diameter is gradually reduced from one end to the majority part to form a truncated conical tapered surface 6b. At the same time, a stopper 6c is formed at the end of the stopper 6c, and the tapered surface 6b surrounds the stopper 6c. The auxiliary support member 10 is press-fitted into the inner side of the opening.

[0019] The auxiliary support member 10 extends in the axial direction of the portion forming the tapered surface 6b of the support member 6. It is formed into a short cylindrical shape that is slightly shorter than its length, and one part of its peripheral wall has a A split slit 10a is provided in a direction inclined at a predetermined angle. A tapered surface 10b facing the tapered surface 6b is formed and is press-fitted into the support member 6. When the width of the slit 10a decreases, the inner diameter decreases accordingly. It has become. The inner diameter of the auxiliary support member 10 is the same as before press-fitting it into the support member 6. is the inner diameter of the portion of the support member 6 that does not form the tapered surface 6b, and the back It is larger than the inner diameter of the coupling ring 9, and is shallowly press-fitted into the support member 6 as shown in FIG. When the ring is the same as or slightly larger than the backup ring 9, it is also shown in Figure 2. When pressed deeply into the support member 6, a tapered surface 6b is formed in the support member 6. The inner diameter of the unfilled part is set to be smaller than the inner diameter of the backup ring 9. There is.

[0020] In the power steering device according to the present invention, the rack shaft 1 is connected to the housing. When supporting the support member inside the housing 2, first place the support member at a predetermined position inside the housing 2. 6 is fitted and fixed in advance, and then the auxiliary support member 10, the backup ring 9, and the shaft are fixed. The sealing member 8 is fitted inside in this order. When inserting the auxiliary support member 10, the support member 6, as shown in Figure 4, and its inner diameter is at least as large as the backup. Keep it at a position that does not become smaller than the inner diameter of the pull 9. In that state, go to the middle part. The rack shaft 1 on which the piston 15 around which the seal ring 16 is wound is fixed is connected to the rack teeth. With the protective sleeve 20 covered on the forming side end of 1a as shown in Fig. 7, from the opening on one side (left side in the figure) of the housing 2 into the inside of the housing 2. The support member 6, the auxiliary support member 10, the backup ring 9, and the shaft seal member 8 are fitted in this order. Insert while

[0021] While pushing the support member 5 onto the rack shaft 1 inserted in this way, the support member 5 is fitted from the other end. This is inserted and fixed into the opening of the housing 2, and attached to both the supporting members 5 and 6. to support the rack shaft 1, and furthermore, the pinion 3 is mounted at a predetermined position in the housing 2. After this is engaged with the rack teeth 1a, attach the support yoke 4 as described above. and the rack shaft 1 is gripped between this and the pinion 3, and at this position and the above-mentioned support The rack shaft 1 is supported at three points including the fixed positions of the supporting members 5 and 6. In this state, the hydraulic pressure A pump supplies pressure oil to the oil chambers on both sides of the piston 15 of the hydraulic cylinder, and the shaft sealing member 8 , press the backup ring 9 and move the auxiliary support member 10 from the position shown in Fig. 4 to the position shown in Fig. 2. Press it deeply into the position shown. In this state, the inner diameter of the auxiliary support member 10 is 6. It is smaller than the inner diameter of any of the backup rings 9, and the rack shaft 1 The gap between them becomes narrower.

[0022]

[Effect of the idea]

As detailed above, in the power steering device of the present invention, the rack shaft is attached to the housing. When inserting the housing and supporting it at three points inside the housing, for example, the thickness of the protective sleeve Even if the inner diameter of the support member is set larger by the amount of support, the auxiliary support member will This makes it possible to narrow the gap between the rack shaft and the rack shaft, reducing the amount of deflection of the rack shaft. The present invention has excellent effects such as strengthening the function of the sealing member.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing how a rack shaft is supported with respect to a housing in a power steering device according to the present invention.

FIG. 2 is an enlarged half-cut view of the support member and its vicinity.

FIG. 3 is a side view and a front view of the auxiliary support member.

FIG. 4 is a half-cut view showing the position of the auxiliary support member when the rack shaft is inserted.

FIG. 5 is a sectional view showing how a rack shaft is supported with respect to a housing in a conventional device.

FIG. 6 is an enlarged half-cut view of the support member and its vicinity in a conventional device.

FIG. 7 is an explanatory view showing the protective sleeve when inserting the rack shaft into the housing.

[Explanation of symbols]

1 Rack axis 1a rack teeth 2 Housing 3 pinion 5,6 Supporting members 7,8 Shaft sealing member 9 Backup ring 10 Auxiliary support members 15 piston 17 Cylinder section

Claims (1)

[Scope of utility model registration request] 1. A rack shaft having rack teeth near one end is inserted into a cylindrical housing, and a support member is provided at one end and an intermediate portion of the housing opposite to the rack teeth; It is supported at three points by the meshing part between the rack teeth and the pinion so as to be able to slide freely in the longitudinal direction of the shaft, and a piston fixed in the middle of the rack shaft is fitted into the cylinder part formed between both supporting members. In a rack and pinion type power steering device which comprises a hydraulic cylinder for steering assistance, the inner circumferential surface of the support member disposed in the middle part of the housing is provided with a support member arranged in the middle part of the housing in the direction in which the rack shaft is inserted into the cylindrical housing. A tapered surface whose diameter is gradually reduced is provided, and at least one split slit extending in the axial direction is provided in the peripheral wall on the inside of this tapered surface, and the outer peripheral surface is formed into a tapered surface corresponding to the tapered surface of the supporting member. A power steering device comprising: an auxiliary support member whose inner diameter is reduced as it is fitted into the support member from the insertion direction of the rack shaft.