JPH0744526Y2 - Rack support structure for rack and pinion type steering system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an improvement of a rack support structure in a rack and pinion type steering device.

[Conventional technology]

The rack and pinion type steering device is a steering system that is composed of a rack that is arranged laterally between the left and right front wheels (steering wheels) of a vehicle, and a pinion that is provided at the tip of the steering wheel shaft so as to mesh with the rack. It has a gear and is configured to convert the rotational displacement associated with the steering wheel operation into a linear displacement in the rack axis direction and turn the front wheels in the desired direction via the steering link mechanism. Compared with this, the structure is relatively simple, the steering performance is excellent, and the arrangement space is advantageous.

By the way, in this type of rack and pinion type device, the rack that meshes with the pinion is a metal support body or the like having a guide groove that is arranged on the bottom face side facing the pinion and that slidably supports the rack in the axial direction thereof. Rack receiver by
Spring means for urging the rack receiving body in a direction in which the rack meshes with the pinion, and an outer end of an assembling hole for assembling these rack supporting parts into the body are closed and a required spring force is given to the spring means. It is supported by a rack support structure composed of a presser plug and the like. And
In such a support structure, the rack support member, which is a metal support member that is biased by spring means, causes the rack to satisfactorily mesh with the pinion, and the rotational displacement due to the handle operation is taken out as a reciprocating motion in the axial direction for steering. The rack receiver plays a role of turning the wheels, and is important for ensuring a smooth meshing state between the rack and the pinion and performing an appropriate and reliable steering operation. Conventionally, such a rack receiver has generally been made of only a metal material, but recently, a rack material made only of a resin material or a combination of a resin material and a member made of a metal material has been proposed. Especially, in the latter case, a metal member can support the rack stably and reliably while maintaining an appropriate rigidity, and a resin member that forms the sliding surface slides between the rack and the rack. It had the advantages of reducing resistance and eliminating problems such as noise.

[Problems to be solved by the device]

However, in the conventional rack receiving body as described above, particularly in the case of having the metal member, there is a problem that a metal tapping sound called so-called rattle noise is generated, for example, when traveling on a bad road. Of course, as described above, the rack receiving body is elastically supported by the spring means interposed between the mounting hole and the holding plug that serves as the fixing portion, and a minute load fluctuation of about the set load is provided. However, it is inevitable that the metal support will hit the presser plug side, and it will be difficult to suppress the rattle noise, for example, when a larger load is applied to the rack due to kickback or the like. Met.

Therefore, a cushioning material such as a sheet-like packing is interposed between the metal support and the press plug, or the entire rack receiver is made of resin to prevent the metal part from directly colliding with the press plug. This has been done conventionally, for example, in Japanese Utility Model Publication No. 59-6564 and Japanese Utility Model Publication No. 59-45149. However, in these cases, the cushioning material and the receiving body made of resin are required to have strength and durability in order to secure meshing with the pinion of the rack. As a result, it is necessary to use a material having a large elastic coefficient, which has a drawback that the rattle noise cannot be completely prevented.

There is also known a structure in which a disc spring receives the load at the time of a large load to suppress the impact noise (see, for example, Japanese Utility Model Laid-Open No. 62-184065), but the rack receiver side and the presser plug The adjustment to obtain the optimum steering force while providing the optimum clearance depends on the machining accuracy of the disc spring.Therefore, in order to satisfy both the clearance and the steering force at the same time, the disc spring, the set spring, etc. There is a drawback that the number of parts management and assembly man-hours increase, and there is also a problem that there is a large variation in the characteristics of the disc spring, which is a problem in practical use,
It is desired to take some measures that can eliminate these problems.

[Means for Solving the Problems]

In order to meet such a demand, a rack support structure in a rack and pinion type steering device according to the present invention is a metal support having a guide groove for slidably supporting a rack engaged with a pinion, and the metal support. The space for determining the set load of the spring means is secured between the spring support that urges the spring means to the rack side and the presser plug that closes the outer end of the mounting hole of the rack support part inside the body so as to give an elastic force. In addition, a buffer consisting of an outer metal cylinder and an elastic cylinder made of rubber or a synthetic resin material, etc., which are coaxially arranged via an annular space and are integrally connected by shifting them by a predetermined amount in the axial direction. It is arranged with a bush interposed.

[Action]

According to the present invention, when a small load is applied, shock absorption is performed by the spring means interposed between the metal support and the pressing plug through the buffer bush, and even if the load exceeds the set load. , The elastic bushing integrally formed by bake, adhesive, etc. between the inner and outer metal cylinders that make up the cushioning bush absorbs by the relative movement of the inner and outer metal cylinders in the axial direction, and is made of metal. It is possible to prevent the rattle noise from being generated by the direct collision between the support and the presser plug.

Further, according to the present invention, the collision bush for preventing rattle noise caused by the collision between the metal support and the presser plug also has a function of determining the set load of the spring means, and this buffer bush is used as the spring. Since it is arranged on the outer peripheral side of the means, no extra space is required in the longitudinal direction of the spring means, and the size can be reduced.

〔Example〕

1 to 4 show an embodiment of a rack support structure in a rack and pinion type steering apparatus according to the present invention. In this embodiment, a rack and pinion type for power steering as illustrated in FIG. 4 is shown. The case where it is applied to a steering device is shown. First, a schematic configuration of a power steering main body portion in a rack and pinion type steering device of this type will be briefly described with reference to FIG. 4. Reference numeral 1 in the drawing is a stub shaft as an input shaft connected to a steering handle side (not shown). Reference numeral 2 denotes an output shaft which is connected to the inner end (left end) side of the stub shaft 1 via a torsion bar 3 and has a pinion 2a which meshes with rack teeth 4a on a rack 4 which constitutes a steering link mechanism (not shown). With the pinion axis,
A safety spline portion 5 is provided between the shafts 1 and 2 as a fail-safe mechanism that allows relative rotational displacement within a predetermined angle range. That is, these shafts 1 and 2 are connected while securing their relative position as a flow path switching valve in a state where they can be relatively rotationally displaced by the torsion of the torsion bar 3, and at the inner end side of the stub shaft 1. When the spline projections provided at predetermined intervals in the circumferential direction and the inner wall portion of the shaft hole on the inner end side of the pinion shaft 2 are engaged in a freely movable state and rotated by a predetermined angle in the circumferential direction. A safety spline portion 5 is constituted by a spline groove portion formed so as to abut and connect both shafts 1 and 2. The inner end of the torsion bar 3 is preliminarily set to the pinion shaft 2.
Is press-fitted into the shaft hole on the side to be connected and fixed, and the outer end extends through the stub shaft 1 to the outer end (right end) side of the stub shaft 1 and the steering handdle side of the stub shaft 1. In the serration portion 1a for coupling, the torsion bar 3 and the torsion bar 3 are connected by a connecting pin 6 which is driven into a pin insertion hole provided in the radial direction.

Here, the body 7 that constitutes the power steering main body
The rotor 8a and the sleeve 8b forming the rotary flow path switching valve 8 described above are integrally provided on the inner ends of the shafts 1 and 2 described above, respectively, and the safety spline portion 5 serves as a switching valve. Of the oil pump P, the oil tank T and the power cylinder left and right chambers C, which are not shown, due to the relative rotational displacement.
It is configured to switch the flow path between L and CR. The specific structure and operation of the rotary flow path switching valve 8 are well known, and detailed description thereof will be omitted.

Reference numeral 10 denotes an assembling hole that is formed by opening the body 7 to the outside for assembling a rack supporting component that supports the back side of the rack 4 that meshes with the pinion 2a of the pinion shaft 2.
A rack 4 having rack teeth 4a meshing with the pinion 2a is disposed in the space on the inner end side substantially orthogonal to the pinion shaft 2, and the rack 4 is fitted into the mounting hole 10 from the outside. A thin resin pad 11a that has been inserted into the guide groove is slidably supported in the axial direction by a metal support 11 made of a sintered alloy material or the like as a rack receiving body, and the outside of the mounting hole 10 A biasing force is applied in a direction of meshing with the pinion 2a by a coil spring 13 as a set spring which is pressed from below in the drawing by a presser plug 12 which is screwed and fixed to a threaded portion 10a on the end side. In the figure, 12a is a lock nut for fixing the presser plug 12 to the body 7. In addition, the resin pad 11a described above is made of a material having self-lubricating property (synthetic resin material such as oil-impregnated polyacetal).
It is possible to exert the effect of improving the steering efficiency by smoothly sliding the rack 4 in the axial direction and elastically supporting the rack 4 against various displacement forces. The metallic support 11 is molded as a molded product by a non-cutting manufacturing method such as sintering using a sintered alloy material or the like.

According to the apparatus 1 of the present embodiment, the rack teeth 4a that mesh with the pinion 2a are the rack teeth 4a that mesh with the pinion teeth.
The lower side surface of the resin is a semi-circular cross section formed by an arc surface, and the resin pad 11 is used as a receiving surface for supporting the same.
The case where the substantially cylindrical metal support 11 having a is used is shown as an example, but the present invention is not limited to this, and a Y-shaped rack and a resin pad 11a and metal support that support the Y-shaped rack are well known in the art. Of course, the body 11 may be used.

According to the present invention, in the rack supporting structure as described above, the metal support 11 having the guide groove for slidably supporting the rack 4 meshed with the pinion 2a and the metal support 11 are racks. The outer end of the mounting hole 10 into the body 7 of the rack supporting part is provided between the metal supporting body 11 and the coil spring 13 which is a spring means for urging to the 4 side so as to provide a required elastic force. As is clear from FIGS. 1 and 2 and the like, a space for determining the set load of the coil spring 13 is secured between the closing plug 12 and the closing plug 12, and the space is arranged on the moving shaft via an annular space. A buffer bush consisting of inner and outer metal cylinders 21 and 22 and an elastic cylinder 23 made of rubber, synthetic resin, or the like, which is fixed by baking or bonding so as to integrally connect them by shifting them by a predetermined amount in the axial direction. Place with 20 in between It has a feature in doing so.

Here, the buffer bush 20 has an inner hole through which the coil spring 13 passes, and secures a space between the metal support 11 and the pressing plug 12 for determining the set load of the coil spring 13. It is arranged along the axial direction of the incorporating hole 10 in the formed gap. Further, the buffer bush 20 is arranged such that the lower end of the inner metal cylinder body 21 is brought into contact with the presser plug 12 and the outer metal cylinder body 22 integrally provided thereto is provided with the elastic metal cylinder body 23. C2 in the axial direction
The outer metal cylindrical body 22 is arranged so as to be displaced by only the above, and the upper end portion of the outer metal cylindrical body 22 is arranged so as to secure a clearance C1 that secures a normal set length of the coil spring 13. The length 1 of the outer metal cylinder 22 and the length l2 of the inner metal cylinder 21 are 1
Is set to be slightly larger, but they may be set to be substantially equal.

Further, in the present embodiment, as is clear from FIGS. 1 and 2, in the elastic cylindrical body 23 interposed between the inner and outer metal cylindrical bodies 21 and 22 and connecting them, a part of both end sides thereof has an annular shape. The elastic bushes 23a, 23b formed by the
0 itself moves in the bush axis direction within the clearance C ₁ ,
It is configured so as to prevent the sound from being generated by colliding with the metal support 11 and the presser plug 12. Here, in the example shown in the figure, the elastic protrusions that are annular around the entire circumference of the elastic cylindrical body 23.
Although 23a and 23b are provided, the point is that an elastic member that protrudes in the axial direction more than the inner and outer metal cylindrical bodies 21 and 22 should intervene. Is also good. However, such elastic protrusions 23a and 23b are not necessarily required, and may be provided as necessary depending on various conditions such as the elastic deformation amount of the elastic cylindrical body 23 and the biasing force of the coil spring 13. It is a thing.

According to the above configuration, when the external force is a small load, the metal support 11 and the presser plug 12 pass through the buffer bush 20.
The impact is absorbed in the clearance C1 by the elastic force of the coil spring 13 interposed between and, and even when a large load exceeding the set load is received, the elasticity that constitutes the impact bush 20. By the relative movement of the inner and outer metal cylinders 21 and 22 by the clearance C2 in the axial direction by the cylinder 23, it is possible to appropriately and reliably absorb the impact force, and as a result, the metal support 11 and the presser plug. It is possible to prevent the rattle sound from directly colliding with 12.

Especially, in such an impact bush 20, the inner and outer metal cylinders are
Due to the relative movements of 21, 22 in the axial direction, the elastic cylindrical body 23
A strong spring constant can be obtained by the shearing force of, the generation of rattle noise can be appropriately suppressed, and a design with a degree of freedom can be facilitated.

Further, according to the above-mentioned configuration, the buffer bush 20 for preventing the rattle noise caused by the collision between the metal support 11 and the pressing plug 12 has a function of determining the set load of the coil spring 13, and Since the impact bush 20 is arranged on the outer peripheral side of the coil spring 13, no extra base is required in the longitudinal direction of the coil spring 13, and the cleaning can be made more compact.

Further, according to such an impact bush 20, since the elastic tubular body 23 is arranged in a ring shape, even if the elastic material swells due to oil or the like, the space between the metal support 11 and the pressing plug 12 is increased. The optimum clearance in the axial direction can be secured in the axial direction, and the required impact function can be exhibited.

When the impact bush 20 is assembled, the clearances C ₁ and C ₂ described above are set to zero, and then
With the position returned by C ₂ as the base point, it is advisable to secure the clearance C ₁ by returning an appropriate amount of return provided between the opposing surfaces of the metal support 11 and the pressing plug 12 of the rack 4 in the conventional structure.

Further, FIG. 3 shows changes in the rack urging force due to the above-described rack support structure, in which the clearance C _{1 is} the urging force due to the spring constant k ₁ of only the coil spring 13, and the clearance C ₂ is greater than that. Until it disappears, coil spring
The spring force fluctuates with the combined spring constant k ₂ of 13 and the elastic cylindrical body 23, and when it exceeds this value, the biasing force is based on the spring constant k ₃ including the resin pad 11a and the like.

The present invention is not limited to the above-described embodiment structure, and the shape, structure, etc. of each part of the rack and pinion type steering device can be appropriately modified and changed, and the locking hole 12 characterizing the present invention can be provided. Various modifications are conceivable, including the shape and structure of the metal support 10 and the resin pad 11 having the locking projections 13 included therein.

[Effect of device]

As described above, according to the rack supporting structure in the rack and pinion type steering device according to the present invention, the metal supporting body having the guide groove for slidably supporting the rack engaged with the pinion and the metal supporting body are provided. Securing a space for determining the set load of the spring means between the spring support biasing the spring means and the presser plug that closes the outer end of the mounting hole of the rack support part in the body so as to give the spring force. In addition, a buffer bush composed of an outer metal cylinder and an elastic cylinder made of rubber or a synthetic resin material, etc., which are coaxially arranged via an annular space and which are integrally coupled by shifting them by a predetermined amount in the axial direction. Since it was arranged to intervene, despite the simple and inexpensive configuration,
The following practically excellent effects are achieved.

That is, according to the present invention, when a small load is applied, the spring means interposed between the metal support and the pressing plug passes through the buffer bush to absorb and absorb a large load, and a large load exceeding the set load is absorbed. Even when received, due to the elastic cylinder that constitutes the buffer bush,
It is excellent in that the cushioning force is absorbed by the relative movement of the outer metal tubular body in the axial direction, and the rattle noise caused by the direct collision between the metal support and the presser plug can be appropriately and surely suppressed. Produce an effect.

In particular, in such a buffer bush, a strong spring constant can be obtained by the shearing force of the elastic cylinder due to the relative movement of the inner and outer metal cylinders in the axial direction, and the generation of rattle noise is more appropriate. It is possible to suppress the above, and it is easy to design with more flexibility.

Further, according to the present invention, the buffer bush for preventing rattle noise caused by the collision between the metal tubular body and the pressing plug also has a function of determining the set load of the spring means, and the impact bush is used for the spring. Since it is arranged on the outer peripheral side of the means, no extra space is required in the longitudinal direction of the spring means, and the entire apparatus can be made more compact.

Further, according to such an impact bush, since the elastic cylindrical body is arranged in a ring shape, even if the elastic material swells due to oil or the like, it is axially arranged between the metal support and the presser plug. The optimum clearance can be secured, and there is also an advantage that the required cushioning function can be exhibited.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part showing an embodiment of a rack support structure in a rack and pinion type steering device according to the present invention,
FIG. 2 is a schematic perspective view showing a cross section of a main part of a cushioning bush which is a feature of the present invention, FIG. 3 is a characteristic diagram for explaining its cushioning characteristic, and FIG. 4 is a diagram to which the present invention is applied. It is a schematic sectional drawing which shows the schematic structure of the power steering type rack and pinion type steering device. 2 …… pinion shaft, 2a …… pinion, 4 …… rack, 4a
...... Rack teeth, 7 ...... Body, 10 ...... Rack support component installation hole, 11 ...... Metal support (tack receiver), 11a ...
… Resin pad, 12 …… Presser plug, 13… Coil spring (set spring), 20… Buffer bush, 21,22…
… Inner and outer metal cylinders, 23 …… elastic cylinders, 23a, 23b …… elastic protrusions.

Claims (1)

[Scope of utility model registration request] 1. A metal support having a guide groove for slidably supporting a rack meshing with a pinion, spring means for urging the metal support toward the rack, and a body of these rack support parts. In a rack support structure in a rack and pinion type steering device, which comprises a pressing plug that closes the outer end of the mounting hole to the spring means and gives a spring force to the spring means, a metal support and a pressing plug are provided in the mounting hole. Between,
An elastic tubular body that secures a space for determining the set load of the spring means, and is coaxially arranged through an annular space, and is integrally connected to the outer metal tubular body by shifting them by a predetermined amount in the axial direction. The rack support structure in the rack and pinion type steering device is characterized in that it is arranged with a buffer bush consisting of and interposed.