JP4468124B2 - Steering vibration damping device - Google Patents

Description

  The present invention relates to a steering vibration attenuating device for attenuating vibration reversely input from a road surface to a power steering device.

  External forces including various vibration components are reversely input to the steering system while the vehicle is running. Such reverse input is transmitted to the steering shaft via the rack shaft and the gear box that constitute the steering device, and so-called steering vibration is generated on the steering shaft.

  Steering vibration mainly includes flutter vibration, judder vibration, kickback, and the like. Flutter vibration is minute vibration in which the steering wheel is swung in the circumferential direction due to tire imbalance. The judder vibration is a minute vibration in which the steering wheel is swung in the rotation direction when the brake is operated due to a thickness variation of the disk rotor. Kickback is a vibration with a relatively large amplitude that is reversely input to the steering system from the road surface when traveling on a rough road.

  As a technology for attenuating these steering vibrations, a dynamic damper is interposed in the transmission path from the left and right wheels to the steering wheel, and the energy of the steering vibration is consumed by the behavior of the dynamic damper, and the amplitude of the reverse input is reduced. Many damping techniques are used.

For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 5-8743), a chamber that houses a movable mass is provided in a hydraulic circuit that supplies hydraulic oil to a cylinder chamber that constitutes a power steering device. When flutter vibration is input to the transmission path leading to this, this flutter vibration is transmitted to the hydraulic circuit side via the hydraulic oil in the cylinder chamber, and the movable mass in the chamber interposed in this hydraulic circuit functions as a dynamic damper. Thus, a technique for attenuating flutter vibration is disclosed.
Japanese Patent Laid-Open No. 5-8743

  However, in the technique disclosed in Patent Document 1, it is necessary to secure a space for providing a chamber in the hydraulic circuit of the power steering apparatus. Furthermore, there is a problem that the structure is complicated and the product cost is increased because the movable mass is housed in the chamber.

  On the other hand, a technique of interposing a dynamic damper on the lower arm of the suspension or the steering shaft is also known. However, in any technique, it is necessary to secure a space for interposing the dynamic damper. However, there is a problem that a sufficient damper effect cannot be exhibited in a portion that easily interferes with other components and cannot secure a sufficient space.

  In view of the above circumstances, the present invention has a simple structure, does not increase the number of parts, does not require a special space for damping a steering vibration, and efficiently reduces the steering vibration at a low cost. An object of the present invention is to provide a steering vibration damping device that can be damped.

In order to achieve the above object, a first steering vibration damping device according to the present invention includes a rack shaft connected to a steering wheel and movable in an axial direction, a rack piston fixed to the rack shaft, and the rack shaft. A power cylinder that penetrates, first and second seal members that are fixed to both ends of the power cylinder and have a seal body that is in sliding contact with the outer periphery of the rack shaft; A third seal member having a seal ring that slidably contacts the inner periphery and divides the inside of the power cylinder into two cylinder chambers, and the seal body of at least one of the first and second seal members is a two-layer structure of a sliding contact lip member to the seal body member and the rack shaft to be fixed to the power cylinder, form the seal body member with a high damping rubber Characterized in that it was.
The second steering vibration damping device includes a rack shaft that is connected to the steering wheel and is movable in the axial direction, a rack piston fixed to the rack shaft, a power cylinder through which the rack shaft passes, and the power cylinder First and second seal members having seal bodies fixed to both ends of the rack shaft and slidably contacting the outer periphery of the rack shaft; and the power cylinder fixed to the rack shaft and slidably contacted to the inner periphery of the power cylinder A third seal member having a seal ring that divides the inside into two cylinder chambers, and an outer periphery that is in sliding contact with an inner peripheral ring member that fixes the seal ring to the rack shaft and an inner peripheral surface of the power cylinder A two-layer structure with a side ring member is used, and the inner ring member is formed of high-damping rubber.

  According to the present invention, a simple structure does not increase the number of parts, it is not necessary to secure a special space for damping a steering vibration, and the steering vibration can be efficiently attenuated at a low cost. Can do.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 to 4 show a first embodiment of the present invention. FIG. 1 is an overall schematic diagram of a power steering apparatus.

  As shown in the figure, the steering shaft 2 of the power steering apparatus 1 is rotatably supported by a vehicle body frame (not shown) via a steering column 3, and one end of the steering shaft 2 extends to the driver's seat side. Is extended to a toe board (not shown) that partitions the driver's seat and the engine room. A steering wheel 4 is fixed to a driver seat side end of the steering shaft 2, and a pinion shaft 5 is connected to a toe board side end. The pinion shaft 5 extends through the toe board to the engine room side.

  A steering gear box 6 extending in the vehicle width direction is disposed in the engine room, and a power cylinder 7 is integrally formed on one side of the steering gear box 6 in the axial direction. As shown in FIGS. 2 and 3, a rack shaft 8 is inserted and supported by the steering gear box 6 and the power cylinder 7 so as to be reciprocally movable. A rack (not shown) formed on the rack shaft 8 is engaged with a pinion formed on the pinion shaft 5 to form a rack and pinion type steering gear mechanism.

  Further, both left and right ends of the rack shaft 8 protrude from end portions of the steering gear box 6 and the power cylinder 7, and a front knuckle 10 is connected to the end portions via tie rods 9. The front knuckle 10 rotatably supports the left and right wheels 11L and 11R and is supported by a vehicle body frame via a king pin (not shown) so as to be steerable.

  Therefore, when the steering wheel 4 is operated and the steering shaft 2 and the pinion shaft 5 are rotated, the rack shaft 8 is moved in the left-right direction by the rotation of the pinion shaft 5, and the front knuckle 10 is moved by the movement to the king pin (not shown). ) And the left and right wheels 11L and 11R are steered in the left-right direction.

  As shown in FIG. 2, the power cylinder 7 is sealed at both ends via first and second sealing members 12, 13, and is on the end opposite to the side continuously connected to the steering gear box 6. Is prevented from coming off by the ring member 14. The power cylinder 7 is partitioned into two cylinder chambers 7a and 7b with a third seal member 15 fixed to the rack shaft 8 interposed therebetween. A control valve 17 is connected to the cylinder chambers 7a and 7b via supply / discharge circuits 16a and 16b.

  As shown in FIG. 1, a supply circuit 18 a and a discharge circuit 18 b are connected to the control valve 17, and the supply circuit 18 a is connected to the reservoir tank 20 via an engine-driven or electric hydraulic pump 19. It is being faced. On the other hand, the discharge circuit 18b faces the reservoir tank 20 directly. Reference numeral 18c is a check valve for preventing the oil in the supply circuit 18a from flowing back to the hydraulic pump 19 side.

  When the steering wheel 4 is rotated, the control valve 17 connected to the pinion shaft 5 opens one supply / discharge circuit 16a (16b) corresponding to the rotation direction of the steering wheel 4, and the hydraulic oil is supplied to one cylinder chamber. To 7a (7b). When the hydraulic oil flows into one of the cylinder chambers 7a (7b), the rack piston 31 is pressed by the hydraulic oil, and the rack shaft 8 is urged in the same direction as the direction of movement by the rotation of the steering wheel 4 to steer. Assist force. When the rack piston 31 moves, the hydraulic oil flowing into the other cylinder chamber 7b (7a) is returned to the reservoir tank 20 via the supply / discharge circuit 16b (16a) and the discharge circuit 18b.

  As shown in FIG. 3, the first seal member 12 and the second seal member 13 that seal both ends of the power cylinder 7 have substantially symmetric shapes. The seal main body 21 of the second seal member 13 is different in that the seal main body 21 of the second seal member 13 is composed of a two-layer structure of a seal main body member 42 and a lip member 43. .

  First, the configuration of the first seal member 12 will be described. The first seal member 12 includes a seal body 21, an annular reinforcing member 22 having a substantially L-shaped cross section that is attached to and integrated with the seal body 21, and a garter spring 23 that is attached to the seal body 21. Yes.

  The seal body 21 is formed in an annular shape using an elastic material such as rubber, an elastomer material, or a polymer material, and an outer peripheral surface 21 a thereof is closely fixed to the inner peripheral surface of the power cylinder 7. Further, a bent end portion of an annular reinforcing member 22 made of a metal material such as a steel plate is integrally embedded on the back surface of the seal body 21 and is reinforced by being fixed by means such as vulcanization adhesion or welding.

  Further, a seal lip 21b slidably contacting the rack shaft 8 is formed on the inner peripheral surface of the seal main body 21, and a garter spring 23 is wound around the outer peripheral side thereof. The garter spring 23 sets the pressing force against the rack shaft 8 of the seal lip 21b.

  Next, the configuration of the second seal member 13 will be described. The seal main body member 42 provided on the seal main body 41 of the second seal member 13 is made of high-damping rubber. The material of the high damping rubber is, for example, natural rubber (NR), isobutylene-isoprene rubber (IIR), styrene-butadiene rubber (SBR), butadiene rubber (BR), or a mixture thereof, and a phenolic resin. In addition, there are those blended with a resin material such as rosin resin.

  FIG. 4 shows the hysteresis characteristics of the high damping rubber. The horizontal axis is the displacement amount X [mm], and the vertical axis is the weighting F [N]. As shown in the figure, high damping rubber has a large hysteresis when it is elastically deformed in response to an input load and when returning from the elastically deformed state, and vibration energy is converted into heat by the hysteresis loss at this time. Is consumed to attenuate the amplitude.

  When the seal body member 42 is made of high-damping rubber, when steering vibration reversely input to the rack shaft 8 is applied to the seal body member 42 via a lip member 43 described later, the seal body member 42 is sheared. It is possible to consume vibration energy and attenuate the amplitude by heat generation due to hysteresis loss that is elastically deformed by stress and tensile stress.

  Steering vibration to be damped in this embodiment mainly includes flutter vibration, ladder vibration, and kickback. The main frequency of each of these vibrations is around 12 to 15 Hz, and the amplitude that is reversely input to the rack shaft 8 by these vibrations is 0.05 mm for flutter vibration, 0.5 mm for ladder vibration, and kickback. Then it is about 1.5mm.

  In general, with such a small amplitude, the rack shaft 8 and the seal body 41 do not slide, and the hydraulic oil flowing into the cylinder chambers 7a and 7b of the power cylinder 7 is only slightly deformed. There is no significant attenuation. In this embodiment, since the seal body member 42 is made of high damping rubber, the minute input amplitude of the steer vibration transmitted to the rack shaft 8 can be damped by elastic deformation of the seal body member 42.

  In addition, the outer peripheral surface 42 a of the seal body member 42 is closely fixed to the inner peripheral surface of the power cylinder 7. Further, a bent portion of the end of the annular reinforcing member 22 made of a steel plate or the like is integrally embedded on the back surface of the seal body 21 for reinforcement. Further, an annular joint member 44 made of a metal material such as a steel plate having an L-shaped cross section is fixed to the inner periphery of the seal body member 42 by means such as vulcanization adhesion or welding.

  Further, a lip member 43 is fixed to the inner periphery of the joining member 44 by means such as vulcanization adhesion or welding. The lip member 43, like the seal body 21 constituting the first seal member 12, is formed in an annular shape using an elastic material such as rubber, an elastomer material, a polymer material, etc. having good wear resistance and sealability. A seal lip 43b slidably contacting the rack shaft 8 is formed on the inner peripheral surface thereof, and a garter spring 23 having the same function as that of the first seal member 12 is wound on the outer peripheral side thereof. Yes.

  On the other hand, as shown in FIG. 3, the rack piston 31 is formed in an annular shape, the inner periphery thereof is pivotally attached to the rack shaft 8, and the claw portion 31 a formed at one end of the rack piston 31 bites into the rack shaft 8. It is fixed in the state, and its back surface is latched by a stopper 32 such as a C-ring to restrict movement in the axial direction. An annular groove 31 b is formed on the outer periphery of the rack piston 31. A seal ring 34 as a third seal member is attached to the annular groove 31 b via an O-ring 33, and the outer peripheral surface 34 a of the seal ring 34 is in sliding contact with the inner peripheral surface of the power cylinder 7. The seal ring 34 is formed of an elastic material such as rubber, elastomer, or polymer material, like the seal body 21.

  In such a configuration, when a steering vibration having a fine amplitude that is not so slid as to slide between the rack shaft 8 and the second seal member 13 is reversely input to the rack shaft 8, the amplitude is reduced. Is transmitted to the seal body member 42 via the lip member 43 of the second seal member 13, and the seal body member 42 is elastically deformed by shear stress and tensile stress. Since the seal main body member 42 is formed of high-damping rubber, heat is generated due to hysteresis loss that occurs during elastic deformation, and vibration energy is consumed by this heat generation and the amplitude is attenuated.

  In this embodiment, the seal body 41 of the second seal member 13 has a two-layer structure, and the seal body member 42 on the side fixed to the power cylinder 7 is formed of high damping rubber. It is not necessary to secure a separate space and the space can be used effectively.

  Further, the rack shaft 8 and the power cylinder can be formed by forming the lip member 43 on the side that directly slides with the rack shaft 8 from a material having good wear resistance and sealability different from the material of the seal body member 42. Steering vibrations can be damped while maintaining the sealing performance and wear resistance between the two.

  In this embodiment, the seal body 41 of the second seal member 13 has a two-layer structure. However, the seal body 21 of the first seal member 12 has a two-layer structure, and the portion fixed to the power cylinder 7 side is high. The same effect can be obtained even when formed of damping rubber.

  FIG. 5 shows a second embodiment of the present invention. In this embodiment, the seal ring 34 constituting the third seal member 15 has a two-layer structure, one of which is formed of a high damping rubber. Further, the second seal member 13 according to the present embodiment has a symmetrical shape with the first seal member 12 shown in the first embodiment. Therefore, the components of the second seal member 12 having a symmetric configuration with the components of the first seal member 12 are denoted by the same reference numerals and description thereof is omitted.

  The seal ring 34 according to this embodiment has a two-layer structure of an inner ring member 35 on the side in contact with the O-ring 33 and an outer ring member 36 whose outer circumferential surface 36a is in sliding contact with the power cylinder 7. A joint surface between the ring members 35 and 36 is fixed to an annular plate-like joint member 37 made of a metal material such as a steel plate by means such as welding or adhesion. Note that the rack piston 31 and the stopper 32 have the same configuration as that of the first embodiment, and a description thereof will be omitted.

  The inner ring member 35 is made of high damping rubber. As the material of the high damping rubber, as in the first embodiment, for example, natural rubber (NR), isobutylene-isoprene rubber (IIR), styrene-butadiene rubber (SBR), butadiene rubber (BR), or the like, or these There exist what mix | blended resin materials, such as a phenol resin and a rosin resin, with the mixture.

  On the other hand, the outer ring member 36 is made of an elastic material such as rubber, elastomer, polymer material, etc., which has good wear resistance and sealability, as in the conventional case.

  In this embodiment, the first and second seal members 12 and 13 have the same configuration as the conventional one, the seal ring 34 provided on the rack piston 31 of the third seal member 15 has a two-layer structure, and the seal ring 34 Since the inner ring member 35 is made of high damping rubber, the amplitude of the steering vibration that is reversely input to the rack shaft 8 is attenuated by elastic deformation of the inner ring member 35. Since it can respond only by the change of 34, the rise in manufacturing cost can be suppressed. Moreover, since conventional parts other than the seal ring can be used as they are, high versatility can be obtained.

  Further, by forming the outer ring member 36 on the side that slides directly with the power cylinder 7 with a material having good wear resistance and sealability different from the material of the inner ring member 35, the rack shaft 8. Steering vibration can be damped while maintaining the sealing performance and wear resistance between the power cylinder 7 and the power cylinder 7.

  The present invention is not limited to the above-described embodiments. For example, both the seal body 41 of the second seal member 13 and the seal ring 34 of the third seal member 15 are incorporated in one power steering device 1. You may do it.

Overall schematic diagram of power steering apparatus according to first embodiment Same sectional view of the power steering device Same as above, enlarged sectional view of the main part of the power steering device Explanatory drawing showing hysteresis characteristics of high damping rubber The principal part expanded sectional view equivalent to FIG. 3 by 2nd form.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Power steering apparatus, 6 ... Steering gear box, 7 ... Power cylinder, 7a, 7b ... Cylinder chamber, 8 ... Rack shaft, 12 ... 1st sealing member, 13 ... 2nd sealing member, 14 ... Ring member, DESCRIPTION OF SYMBOLS 15 ... 3rd seal member, 21 ... Seal main body, 21a ... Outer peripheral surface, 21b ... Seal lip, 31 ... Rack piston, 34 ... Seal ring, 35 ... Inner peripheral side ring member, 36 ... Outer peripheral side ring member, 37, 44 ... joining member, 41 ... seal body, 42 ... seal body member, 42a ... outer peripheral surface, 43 ... lip member, 43b ... seal lip

Agent Patent Attorney Susumu Ito

Claims (4)

A rack shaft connected to the steering wheel and movable in the axial direction;
A rack piston fixed to the rack shaft;
A power cylinder through which the rack shaft passes;
First and second seal members having seal bodies fixed to both ends of the power cylinder and in sliding contact with the outer periphery of the rack shaft;
A third seal member fixed to the rack shaft and having a seal ring that slidably contacts the inner periphery of the power cylinder and divides the power cylinder into two cylinder chambers;
The seal body of at least one of the first and second seal members has a two-layer structure of a seal body member fixed to the power cylinder and a lip member slidably contacting the rack shaft,
A steering vibration damping device, wherein the seal body member is formed of high damping rubber . Steering vibration damping device according to claim 1, characterized by being formed integrally with the seal body member and said lip member through the bonding member. A rack shaft connected to the steering wheel and movable in the axial direction;
A rack piston fixed to the rack shaft;
A power cylinder through which the rack shaft passes;
First and second seal members having seal bodies fixed to both ends of the power cylinder and in sliding contact with the outer periphery of the rack shaft;
A third seal member fixed to the rack shaft and having a seal ring that slidably contacts the inner periphery of the power cylinder and divides the power cylinder into two cylinder chambers;
A two-layer structure of an inner ring member that fixes the seal ring to the rack shaft and an outer ring member that is in sliding contact with the inner surface of the power cylinder;
The inner peripheral-side ring member <br/> be formed with high damping rubber characteristics and to Luz tearing vibration damping device a. 4. The steering vibration attenuating device according to claim 3, wherein both the ring members are integrally formed through a joining member.

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