Linear motion damper and steering device

Abstract

To provide a linear motion damper capable of improving workability of assembly and maintenance, and to provide a steering device including the linear motion damper.SOLUTION: A steering device 100 includes a linear motion damper 120 between a rack bar 103 and a rack end 106. In the linear motion damper 120, a relative displacement body 140 is provided within an internal chamber formation body 121 formed in a cylindrical shape so as to be displaced in a reciprocating manner. In the internal chamber formation body 121, a first inner chamber 125a and a second inner chamber 125b are respectively formed at both sides of a valve support part 123 supporting a first circulation control valve 127 and a second circulation control valve 128, and an elastic body storage part 130 is formed adjacently to the second inner chamber 125b. The elastic body storage part 130 is formed in a state of being communicated with the outside air and stores a returning elastic body 131 in an inside thereof.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a linear motion damper that damps kinetic energy in linear motion and a steering device equipped with this linear motion damper. [Background technology]

[0002] Conventionally, there have been linear dampers that damp kinetic energy in linear motion. For example, Patent Document 1 below discloses a linear damper that reduces impact loads occurring between a rack end and a rack housing in a steering device of a self-propelled vehicle by restricting the flow of fluid to the rack end, which is displaced relative to the rack housing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2021 / 246082 publication Summary of the Invention

[0004] However, in the linear damper disclosed in Patent Document 1, a return elastic body that elastically presses the relative displacement body to which the rack end is connected toward the rack end is provided inside an inner chamber filled with fluid, which poses a problem in that it is difficult to perform the assembly and maintenance operations of the linear damper.

[0005] The present invention has been made to address the above-mentioned problems, and its object is to provide a linear damper that can improve the ease of assembly and maintenance, and a steering device equipped with this linear damper.

[0006] In order to achieve the above-mentioned object, the present invention is characterized in that it comprises an inner chamber forming body that is formed in a cylindrical shape and has an inner chamber that liquid-tightly contains a fluid inside the cylindrical portion, a relative displacement body that is slidably fitted into the inner chamber forming body and displaces relative to the inner chamber forming body, and a flow control valve that is provided on at least one of the inner chamber forming body and the relative displacement body and allows the fluid to flow while restricting the flow of the fluid, and is a direct-acting damper that is placed between two objects to be attached that are linearly displaced relative to each other and attenuates the external force received by this relative displacement by restricting the flow of the fluid, and is provided with a return elastic body that imparts an elastic force to the relative displacement body to elastically absorb the external force, and the inner chamber forming body has an elastic body accommodating portion inside the inner chamber forming body for accommodating the return elastic body while communicating with the outside air, and the return elastic body is accommodated in the elastic body accommodating portion.

[0007] According to this, the linear damper is configured to have an elastic body accommodating section for accommodating the return elastic body inside the inner chamber forming body while being connected to the outside air, so that the return elastic body can be easily accommodated in the elastic body accommodating section, thereby improving the ease of assembly and maintenance of the linear damper.

[0008] Another feature of the present invention is that in the linear damper, the elastic body accommodating portion is formed in a state in which it is connected to the outside air through an opening formed at one end of the inner chamber forming body which is large enough to allow the return elastic body to be inserted and removed.

[0009] According to this, the linear damper is formed in a state where the elastic body accommodating portion is connected to the outside air through an opening formed at one end of the inner chamber forming body which is large enough to allow the return elastic body to be inserted and removed, so that the return elastic body can be easily inserted and removed into the inner chamber forming body during assembly and maintenance of the linear damper.

[0010] Another feature of the present invention is that the linear damper further comprises an elastic body receiving body attached to the opening in the inner chamber forming body and receiving the elastic force of the return elastic body.

[0011] According to this, the linear damper is provided with an elastic body receiving body that is attached to the opening in the inner chamber forming body and receives the elastic force of the return elastic body, thereby preventing the return elastic body from flying out from the inner chamber forming body and improving the workability of assembling and maintaining the linear damper.

[0012] Another feature of the present invention is that in the linear damper, the elastic body receiving body is positioned at a position where it will abut one of the two objects to be attached due to the relative displacement of the inner chamber forming body, and has an abutment portion made of an elastic body that elastically receives this abutment.

[0013] According to this, the linear damper has an abutment portion made of an elastic material that is disposed at a position where the elastic receiving body abuts one of the two mounting objects and elastically absorbs the impact, thereby effectively suppressing the generation of impact noise or impact when the abutment occurs. In this case, the abutment portion can be made of an elastomer material. Here, the elastomer material is a rubber material or a resin material that can elastically absorb the impact when the abutment portion collides with the object. More specifically, the elastomer material can be a thermosetting elastomer material (e.g., vulcanized rubber, urethane rubber, silicone rubber, fluororubber, etc.) or a thermoplastic elastomer material (e.g., styrene-based, olefin-based, PVC-based, urethane-based, or amide-based resin, etc.). It goes without saying that the abutment portion can also be made of a material other than an elastomer material, such as a metal leaf spring or coil spring.

[0014] Another feature of the present invention is that in the linear damper, the inner chamber has a first inner chamber and a second inner chamber through which fluid flows via a flow control valve, and the relative displacement body has a first inner chamber forming wall that forms the first inner chamber by expanding or reducing the volume of the first inner chamber through the relative displacement of the relative displacement body, and a second inner chamber forming wall that forms the second inner chamber by expanding or reducing the volume of the second inner chamber through the relative displacement of the relative displacement body, and one of the first inner chamber forming wall and the second inner chamber forming wall forms the elastic body accommodating portion by expanding or reducing the volume of the elastic body accommodating portion through the relative displacement of the relative displacement body.

[0015] According to this, the linear damper has a first inner chamber forming wall and a second inner chamber forming wall in which the relative displacement body forms the first inner chamber and the second inner chamber, respectively, and one of the first inner chamber forming wall and the second inner chamber forming wall forms the elastic body accommodating section while expanding or reducing the volume of the elastic body accommodating section, thereby simplifying and miniaturizing the device configuration.

[0016] Furthermore, the present invention can be embodied not only as an invention of a direct acting damper, but also as an invention of a steering device equipped with this direct acting damper.

[0017] Specifically, the steering device includes a rod-shaped steering shaft that rotates when a steering wheel is operated, a rod-shaped rack bar that converts the rotational motion of the steering shaft into reciprocating motion in the axial direction and transmits it, intermediate connectors that are connected to both ends of the rack bar and directly or indirectly connect the wheels to be steered to the ends, and a rack housing that covers the rack bar, and further includes the linear damper described in claim 1, which is provided between the rack housing and the rack bar or the intermediate connector and attenuates impacts from the wheels and / or impacts due to inertial forces from the steering shaft side. As a result, the steering device according to the present invention can be expected to have the same effects as the linear damper described above.

[0018] In this case, in the steering device, the relative displacement body may be connected to the intermediate connector, and the inner chamber forming body may be formed so as to come into contact with or be separated from the rack housing by the reciprocating motion of the rack bar.

[0019] According to this, in the steering device of the present invention, the relative displacement body is connected to the intermediate connecting body, the inner chamber forming body is formed so as to contact or move away from the rack housing depending on the reciprocating motion of the rack bar, and the damper is provided on the intermediate connecting body such as the tie rod or rack end, which makes it easy to perform maintenance or replacement of the linear damper. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is an explanatory diagram schematically illustrating an outline of the overall configuration of a steering device according to an embodiment of the present invention; [Figure 2] 2 is a perspective view showing the outline of the external configuration of a linear damper that constitutes the steering device shown in FIG. 1, as viewed from the rack end connecting portion side of a relative displacement body. FIG. [Figure 3] 2 is a perspective view showing the outline of the external configuration of a linear damper that constitutes the steering device shown in FIG. 1, as viewed from the abutment side. FIG. [Figure 4] 2 is a front view showing the outline of the external configuration of the linear damper shown in FIG. 1, as viewed from the abutment side. [Figure 5] 5 is a cross-sectional view showing an outline of the internal configuration of the linear damper as seen from line 5-5 shown in FIG. 4. [Figure 6] 6 is a cross-sectional view showing a state at the moment when an inner chamber forming body comes into contact with a rack housing in the linear-acting damper shown in FIG. 5. FIG. [Figure 7] 7 is a cross-sectional view showing a state in which an inner chamber forming body is pressed toward a rack housing in the linear-acting damper shown in FIG. 6. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] An embodiment of a steering device including a linear damper according to the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram illustrating a schematic overview of the overall configuration of a steering device 100 according to the present invention. FIG. 2 is a perspective view of the outline of the external configuration of a linear damper 120 constituting the steering device 100 shown in FIG. 1, seen from the rack end connecting portion side of a relative displacement body 140. FIG. 3 is a perspective view of the outline of the external configuration of the linear damper 120 constituting the steering device 100 shown in FIG. 1, seen from the abutment portion 134 side. FIG. 4 is a front view of the outline of the external configuration of the linear damper 120 shown in FIG. 1, seen from the abutment portion 134 side. FIG. 5 is a cross-sectional view showing the outline of the internal configuration of the linear damper 120, seen from line 5-5 shown in FIG. 4. Note that FIGS. 2 and 3 illustrate the linear damper 120 together with the rack bar 103 and socket body 108, which do not constitute the linear damper 120.

[0022] The steering device 100 is a mechanical device for steering two front wheels (or rear wheels) of a four-wheeled self-propelled vehicle (not shown) in the left and right directions.

[0023] (Configuration of steering device 100) The steering device 100 includes a steering wheel 101. The steering wheel 101 is an operator (i.e., a handle) that allows the driver of the self-propelled vehicle to manually control the direction of travel, and is made of a resin or metal material formed into an annular shape. A steering shaft 102 is connected to the steering wheel 101.

[0024] The steering shaft 102 is a rod-shaped component that rotates around an axis in response to clockwise or counterclockwise rotation of the steering wheel 101, and is configured by connecting one or more metal rods via universal joints or the like. The steering shaft 102 has the steering wheel 101 connected to one end, and a pinion gear 102a formed at the other end and connected to a rack bar 103.

[0025] The rack bar 103 is a rod-shaped component that transmits the steering force and steering amount for each of the two wheels 112 to the knuckle arms 111 by reciprocating in the axial direction, and is made of metal. In this case, a rack gear 103a is formed on a part of the rack bar 103, and is meshed with a pinion gear 102a of the steering shaft 102. In other words, the pinion gear 102a and the rack gear 103a form a rack and pinion mechanism (steering gearbox) that converts the rotational motion of the steering shaft 102 into the reciprocating linear motion of the rack bar 103.

[0026] The rack bar 103 has both axial ends exposed from the rack housing 104, with the rack and pinion mechanism covered by the rack housing 104. Wheels 112 are connected to both ends of the rack bar 103 exposed from the rack housing 104 via linear dampers 120, intermediate connectors 105, and knuckle arms 111, respectively.

[0027] The rack housing 104 is a component that covers and protects the main parts such as the rack and pinion mechanism of the rack bar 103, and is made of a cylindrical metal material. The rack housing 104 is fixedly attached to the chassis (not shown) of the self-propelled vehicle.

[0028] The intermediate connector 105 is a component for transmitting the steering force and steering amount transmitted from the rack bar 103 to the knuckle arm 111, and is mainly composed of a rack end 106 and a tie rod 110. The rack end 106 is a component that movably connects the tie rod 110 to the tip end of the rack bar 103 and to which the linear damper 120 is connected, and is mainly composed of a stud body 107 and a socket body 108.

[0029] The stud body 107 is a component for movably connecting the tie rod 110 to the socket body 108, and is made of a metal material formed into a round bar shape. The stud body 107 has a spherical ball portion 107a formed at one end (the left side in the figure) and a male screw portion (not shown) that screws onto the end of the tie rod 110 formed at the other end (the right side in the figure).

[0030] Socket body 108 is a component for movably connecting stud body 107 to the tip end of relative displacement body 140, and is configured by forming a metal material into a round bar shape. More specifically, socket body 108 is primarily configured by socket main body 108a and connecting portion 108b. Socket main body 108a is a portion that holds ball portion 107a in a slidable state, and is formed in a concave spherical shape that covers ball portion 107a. Connecting portion 108b is a shaft-shaped portion that is connected to relative displacement body 140, and is formed with a male screw that screws into relative displacement body 140.

[0031] The tie rod 110 is a component that movably connects the knuckle arm 111 to the tip of the rack end 106, and is configured by a ball joint movably attached to the tip of a rod-shaped tie rod body. The knuckle arm 111 is a metal component that holds the wheel 112 relative to the tie rod 110 and transmits the steering force and steering amount transmitted from the tie rod 110 to the wheel 112, and is formed in a shape with multiple rod-shaped bodies extending from the periphery of a cylindrical portion. The wheels 112 are a pair of left and right components that roll on the road surface to move the self-propelled vehicle forward or backward, and are configured by rubber tires attached to the outside of metal wheels.

[0032] The linear dampers 120 are devices for absorbing the inertial force from the steering shaft 102 side and / or the strong pressing force (impact) transmitted from the wheels 112, and are provided between each of the left and right intermediate connectors 105 and both ends of the rack bar 103. The linear dampers 120 include an inner chamber forming body 121.

[0033] The inner chamber forming body 121 includes a first inner chamber 125a, a second inner chamber 125b, and an elastic body accommodating portion 130. The inner chamber forming body 121 is a component that supports the relative displacement body 140 while forming the first flow control valve 127, the second flow control valve 128, and the relative displacement body 140, and is configured by forming a metal material into a cylindrical shape. The inner chamber forming body 121 has a valve support portion 123 formed in the axial center of the inner circumferential surface 122. The valve support portion 123 is a portion that supports the first flow control valve 127, the second flow control valve 128, and the relative displacement body 140, and is formed by projecting inward in the radial direction from the inner circumferential surface 122 in an annular shape.

[0034] The valve support portion 123 has four through holes (only two shown) formed at equal intervals along the circumferential direction and penetrating in the axial direction, with a first flow control valve 127 (only one shown) fitted and held in three of these four through holes, and a second flow control valve 128 fitted and held in the remaining through hole. A relative displacement body 140 is slidably fitted into the inner circumferential surface of the valve support portion 123 with a seal ring 124 made of an elastic body fitted in. This forms a first inner chamber 125a and a second inner chamber 125b on either side of the inner chamber forming body 121 in the axial direction of the valve support portion 123.

[0035] The first inner chamber 125a and the second inner chamber 125b are portions that liquid-tightly accommodate the fluid 126, and are formed in the shape of an annular cylinder extending in the axial direction on the outer periphery of the relative displacement body 140. That is, the first inner chamber 125a and the second inner chamber 125b are formed as spatial regions between the relative displacement body 140 and the inner chamber forming body 121. In this case, the first inner chamber 125a is formed between the first inner chamber forming wall 142 of the relative displacement body 140 and the valve support portion 123 in a cylindrical portion that is formed in an open state at the end of the inner chamber forming body 121 on the right side in the figure.

[0036] Second inner chamber 125b is formed between second inner chamber forming wall 145 of relative displacement body 140 and valve support portion 123 in a cylindrical portion formed in an open state at the left end of inner chamber forming body 121 in the drawing. The volumes of first inner chamber 125a and second inner chamber 125b change depending on the position of relative displacement body 140, which slides back and forth within inner chamber forming body 121. First inner chamber 125a and second inner chamber 125b correspond to the inner chambers according to the present invention.

[0037] The fluid 126 is a substance that exerts a damping function on the direct-acting damper 120 by the resistance it generates when it flows through each of the three first flow control valves 127 disposed between the first internal chamber 125a and the second internal chamber 125b. The fluid 126 fills the space formed by the first internal chamber 125a and the second internal chamber 125b. The fluid 126 is composed of a liquid, gel, or semi-solid substance having a flowability and viscosity according to the specifications of the direct-acting damper 120. In this case, the viscosity of the fluid 126 is appropriately selected according to the specifications of the direct-acting damper 120. In this embodiment, the fluid 126 is composed of oil, such as mineral oil or silicone oil. The fluid 126 is indicated by hatching within a dashed circle in FIGS. 5 to 7.

[0038] Each of the three first flow control valves 127 is configured as a valve that allows bidirectional flow while restricting the flow of the fluid 126 between the first internal chamber 125a and the second internal chamber 125b. In this case, restricting the flow of the fluid 126 in the first flow control valve 127 means that the fluid 126 does not flow easily in the flow direction of the fluid 126 in the second flow control valve 128 under the same conditions (for example, pressure, viscosity of the working fluid, etc.).

[0039] The second flow control valve 128 is configured as a valve that allows the fluid 126 to flow from the second inner chamber 125b side to the first inner chamber 125a side, and prevents the fluid 126 from flowing from the first inner chamber 125a side to the second inner chamber 125b side.

[0040] The elastic body accommodating portion 130 is a portion that accommodates the return elastic body 131, and is formed in the shape of an annular cylinder extending in the axial direction outside the outer periphery of the relative displacement body 140 within the inner chamber forming body 121. In this case, the elastic body accommodating portion 130 is formed within a cylindrical portion formed with an opening 130a that opens at the left end of the inner chamber forming body 121 in the figure, on the opposite side of the second inner chamber 125b with respect to the second inner chamber forming wall 145 of the relative displacement body 140. In other words, the elastic body accommodating portion 130 is formed adjacent to the second inner chamber 125b, separated by the second inner chamber forming wall 145, within the cylindrical portion that is common to the second inner chamber 125b. This elastic body accommodating portion 130 is formed at the left end of the inner chamber forming body 121 in the figure with an opening that is larger than the outer diameter of the return elastic body 131.

[0041] The return elastic body 131 is a component for elastically pressing the second inner chamber forming wall 145 and the first inner chamber forming wall 142 of the relative displacement body 140 against the right end portions in the second inner chamber 125b and the first inner chamber 125a, respectively, as shown in the figure, and is configured by arranging a plurality of metal wave springs one on top of the other in the axial direction of the elastic body accommodating portion 130. One end portion (the right end portion in the figure) of this return elastic body 131 elastically presses the second inner chamber forming wall 145, and the other end portion (the left end portion in the figure) elastically presses the elastic body receiving body 133. In addition, a cover body 132 is provided on the outer periphery of these return elastic bodies 131.

[0042] The cover 132 is a component for preventing the wave spring from resonating due to vibrations caused by the operating state of the self-propelled vehicle, such as the engine or the characteristics of the road surface on which the self-propelled vehicle is traveling, and is made of an elastic material such as an elastomer that can dampen the vibrations of the return elastic body 131. In this embodiment, the cover 132 is made of a cylindrical rubber material that comes into close contact with the outer periphery of a portion of the wave spring that constitutes the return elastic body 131. Note that the cover 132 may be configured to cover the entire wave spring that constitutes the return elastic body 131.

[0043] The elastic body receiver 133 is a component that receives the elastic force of the return elastic body 131 and supports the abutment portion 134, and is configured by forming a metal material into a cylindrical shape. More specifically, the elastic body receiver 133 has a recessed fitting portion 133a formed at the end on the right side in the figure, into which the return elastic body 131 fits to regulate its position, and a male thread is formed on the outside of this fitting portion 133a, which screws into an opening 130a that constitutes the end on the left side in the figure of the inner chamber forming body 121. Furthermore, the elastic body receiver 133 has a ring-shaped recessed groove formed at the end on the left side in the figure, into which the abutment portion 134 fits.

[0044] The abutment portion 134 is a component for absorbing the impact when the linear damper 120 collides with the rack housing 104, and is configured by forming an elastically deformable elastic body into a cylindrical shape. In this embodiment, the abutment portion 134 is configured by forming a rubber material into a cylindrical shape with the same outer and inner diameters as the elastic body receiving body 133. An elasticity adjustment hole 134a is formed in this abutment portion 134 along the circumferential direction.

[0045] The elasticity adjustment holes 134a are portions for adjusting the elastic force of the abutting portion 134 and are configured as through holes or bottomed holes. In this embodiment, the elasticity adjustment holes 134a are configured as bottomed holes with a depth approximately half the axial length of the abutting portion 134 and evenly spaced between three circumferentially arranged bolts 135. The abutting portion 134 has three through holes formed at equal intervals along the circumferential direction, and the bolts 135 that threadably engage with the elastic body receiver 133 pass through each of these through holes, thereby attaching the elastic body accommodating portion 130 to the elastic body receiver 133. That is, the elastic body accommodating portion 130 is open to the outside at the end on the left side of the inner chamber forming body 121 in the drawing, with the opening 130a partially blocked by the elastic body receiver 133 and the abutting portion 134, and is in communication with the outside air.

[0046] The relative displacement body 140 is a component that connects the rack bar 103 and the rack end 106 to each other and that forms the first inner chamber 125a and the second inner chamber 125b together with the inner chamber forming body 121, and is made of a metal material formed into a round bar shape. The relative displacement body 140 is mainly composed of an inner chamber facing portion 141, a first inner chamber forming wall 142, a second inner chamber forming wall 145, a rack end connecting portion 148, a rack bar connecting portion 149, and a compensation device accommodating portion 150.

[0047] The inner chamber facing portion 141 is a portion that forms the first inner chamber 125a and the second inner chamber 125b, respectively, and is a portion on which the valve support portion 123 slides, and is configured with a smooth curved surface that has a circular cross section. The inner chamber facing portion 141 is formed in the center of the relative displacement body 140 in the axial direction.

[0048] The first inner chamber forming wall 142 is a part that forms the first inner chamber 125a and slides on the inner circumferential surface 122 of the inner chamber forming body 121 to press the fluid 126, and is formed in a flange-like protrusion at one end (the right side in the figure) of the inner chamber facing part 141. In this case, the first inner chamber forming wall 142 is formed integrally with the relative displacement body 140 using the same material. The inner circumferential surface 122 of the inner chamber forming body 121 is slidably fitted onto the outer periphery of this first inner chamber forming wall 142 with a seal ring 143 made of an elastic body fitted therein. In addition, a first displacement limit defining part 144 is provided on the end face of the first inner chamber 125a side of the first inner chamber forming wall 142.

[0049] The first displacement limit defining portion 144 is a component that defines one of the displacement limits at both ends of the displacement range of the relative displacement body 140 when the first inner chamber forming wall 142 displaces toward the valve support portion 123 and hits against it, and that cushions the impact when the first displacement limit defining portion 144 hits against it, and is configured by forming an elastically deformable elastic body into a circular ring shape. In this embodiment, the first displacement limit defining portion 144 is made of a rubber material. The first displacement limit defining portion 144 is also formed into a tapered cone shape with an outer diameter that is larger on the first inner chamber forming wall 142 side than on the valve support portion 123 side.

[0050] The second inner chamber forming wall 145 is a part that forms the second inner chamber 125b and the elastic body accommodating portion 130, and slides on the inner circumferential surface 122 of the inner chamber forming body 121 to press the fluid 126, and is provided in a flange-like projection at the other end (left side in the figure) of the inner chamber facing portion 141. In this case, the second inner chamber forming wall 145 slides inside the inner chamber forming body 121 while receiving the elastic force of the return elastic body 131 housed in the elastic body accommodating portion 130.

[0051] The second inner chamber forming wall 145 is formed in an annular shape from a metal material separate from the relative displacement body 140, and is integrated with the relative displacement body 140 by being screwed onto the outer periphery of the relative displacement body 140. In this case, the inner periphery 122 of the inner chamber forming body 121 is slidably fitted onto the outer periphery of the second inner chamber forming wall 145 with a seal ring 146 made of an elastic material fitted therein. A receiving recess 145a into which the return elastic body 131 fits is formed as an annular recess on the end face of the second inner chamber forming wall 145 facing the elastic body accommodating portion 130. Meanwhile, a second displacement limit defining portion 147 is provided on the end face of the second inner chamber forming wall 145 facing the second inner chamber 125b.

[0052] The second displacement limit defining portion 147 is a component that defines the other displacement limit at both ends of the displacement range of the relative displacement body 140 when the second inner chamber forming wall 145 displaces toward the valve support portion 123 and hits against it, and that cushions the impact when the second displacement limit defining portion 147 hits against it, and is configured by forming an elastically deformable elastic body into a circular ring shape. In this embodiment, the second displacement limit defining portion 147 is configured from a rubber material.

[0053] The rack end connecting portion 148 is a portion that connects the socket body 108 of the rack end 106, and is formed in a bottomed hole that extends in the axial direction of the relative displacement body 140 and opens at the end on the right side in the figure. In this case, the rack end connecting portion 148 has a female thread formed on the inner circumferential surface of the bottomed hole into which the male thread of the connecting portion 108b of the socket body 108 is threadably fitted.

[0054] The rack bar connecting portion 149 is a portion that connects the rack bar 103, and is configured by forming a male screw on the inner surface of a bottomed hole that extends in the axial direction of the relative displacement body 140 and opens at the end on the left side of the figure, into which a female screw formed at the end of the rack bar 103 is threadedly fitted.

[0055] The compensation device accommodating portion 150 is a portion for liquid-tightly accommodating the volume change compensation device 153, and is formed as a bottomed hole integrally with the rack end connecting portion 148. This compensation device accommodating portion 150 communicates with the second inner chamber 125b via an inner chamber communication passage 151, and also communicates with the atmosphere outside the linear damper 120 via an atmosphere communication passage 152.

[0056] Volume change compensation device 153 is a device that compensates for volume changes caused by expansion or contraction due to temperature changes of fluid 126 in first inner chamber 125a and second inner chamber 125b. This volume change compensation device 153 is configured by accommodating a piston that slides back and forth within compensation device accommodating section 150 while being elastically pressed toward inner chamber communicating passage 151 by a coil spring. In this case, the space that accommodates the coil spring communicates with the atmosphere outside linear damper 120 via atmosphere communicating passage 152.

[0057] (Assembly of the linear damper 120) Here, the assembly work of the linear damper 120 will be described. The worker prepares the machined inner chamber forming body 121, elastic body receiving body 133, relative displacement body 140, and second inner chamber forming wall 145. The worker also prepares the commercially available seal ring 124, fluid 126, first flow control valve 127, second flow control valve 128, return elastic body 131, bolt 135, seal ring 146, and volume change compensation device 153. The worker also prepares the molded cover body 132, abutment portion 134, first displacement limit defining portion 144, and second displacement limit defining portion 147.

[0058] Next, the worker assembles the seal ring 124, the first flow control valve 127, and the second flow control valve 128 to the inner chamber forming body 121, and also assembles the relative displacement body 140 inside the inner chamber forming body 121. In this case, the worker assembles the relative displacement body 140, to which the volume change compensation device 153 is assembled, inside the inner chamber forming body 121. Next, the worker assembles the second inner chamber forming wall 145, to which the seal ring 146 is assembled, to the relative displacement body 140 assembled to the inner chamber forming body 121. Then, the worker fills the first inner chamber 125a, the second inner chamber 125b, and the compensation device accommodating portion 150, which are formed by assembling the relative displacement body 140 inside the inner chamber forming body 121, with the fluid 126.

[0059] Next, the worker accommodates the return elastic body 131 in the elastic body accommodating portion 130 formed by assembling the relative displacement body 140 in the inner chamber forming body 121. In this case, the worker places the cover body 132 over a portion of the wave spring that constitutes the return elastic body 131, and accommodates it in the elastic body accommodating portion 130 through the opening 130a.

[0060] Next, the worker attaches the abutment portion 134 to the elastic body receiver 133 with the bolt 135, and then screws the elastic body receiver 133 into the opening 130a of the inner chamber forming body 121 to thread-fit it. In this case, the worker can attach the abutment portion 134 and the elastic body receiver 133 to the inner chamber forming body 121 by screwing the elastic body receiver 133 into the opening 130a of the inner chamber forming body 121 while resisting the elastic force of the return elastic body 131 housed in the elastic body housing portion 130.

[0061] That is, the worker can assemble the return elastic body 131 by inserting the return elastic body 131 into the elastic body accommodating section 130, which opens through the opening 130a on the left side of the inner chamber forming body 121 in the figure, and closing the opening 130a of the elastic body accommodating section 130 with the elastic body receiving body 133 and the abutting section 134. In this case, because the elastic body receiving body 133 and the abutting section 134 of the elastic body accommodating section 130 are each formed in a cylindrical shape, the elastic body accommodating section 130 is not completely closed and remains in communication with the outside air. This allows the worker to assemble the linear damper 120.

[0062] Next, the worker installs the assembled linear damper 120 between two objects to be installed. In this embodiment, the worker installs the assembled linear damper 120 between the rack bar 103 and the rack end 106. More specifically, the worker threadably engages the rack bar connecting portion 149 of the relative displacement body 140 with the rack bar 103, and threadably engages the rack end connecting portion 148 with the connecting portion 108b. This allows the worker to install the linear damper 120 in the steering device 100. That is, the worker can remove the linear damper 120 from the steering device 100 by reversing the above-described procedure, and then remove the elastic body receiver 133 and the abutting portion 134 from the inner chamber forming body 121, thereby performing maintenance on the return elastic body 131.

[0063] (Operation of the steering device 100) Next, the operation of the steering device 100 configured as above will be described. The steering device 100 is incorporated inside a four-wheeled self-propelled vehicle (not shown) as a mechanism for steering the steered wheels (for example, two front wheels) of the vehicle in the left-right direction. The steering device 100 changes the orientation of the two wheels 112 in response to the operation of the steering wheel 101 by the driver of the self-propelled vehicle, thereby determining the traveling direction of the self-propelled vehicle.

[0064] When such a self-propelled vehicle is being driven, the linear damper 120 in the steering device 100 acts when the rack bar 103 is displaced close to its left-right displacement limit in relation to the pinion gear 102a. In this case, the displacement limit of the rack bar 103 is the left-right steering limit of the wheels 112, and this occurs when the driver of the self-propelled vehicle turns the steering wheel 101 clockwise or counterclockwise close to the rotation limit, or when the wheels 112 collide with an obstacle such as a curb and a large input is applied to the rack bar 103 from the wheel 112 side.

[0065] First, a case will be described in which no external force acts on the linear damper 120 and the linear damper 120 does not operate. As shown in Fig. 5, in a range in which the rack bar 103 does not reach the vicinity of the displacement limit, such as when the wheels 112 of the self-propelled vehicle are not steered to the vicinity of the steering limit, the linear damper 120 does not operate because the inner chamber forming body 121 does not collide with the rack housing 104. In this case, as shown in Fig. 5, the linear damper 120 has the inner chamber forming body 121 elastically pressed to the left side in the displacement range of the inner chamber forming body 121 by the return elastic body 131, and the second inner chamber forming wall 145, which defines the displacement limit, is elastically pressed against the valve support portion 123 via the second displacement limit defining portion 147.

[0066] Next, a case where an external force acts on the linear damper 120 and the linear damper 120 operates will be described. As shown in Fig. 6, when the rack bar 103 reaches near its displacement limit, such as when the wheels 112 of the self-propelled vehicle are steered to near their steering limit, the end of the inner chamber forming body 121 of the linear damper 120 comes into contact with the rack housing 104 and starts operating. In other words, the rack housing 104 corresponds to the other of the two attachment objects according to the present invention. The intermediate connecting body 105 corresponds to one of the two attachment objects according to the present invention.

[0067] In this case, first, the abutment portion 134 of the linear damper 120 abuts against the rack housing 104 and undergoes elastic compression deformation, thereby attenuating the impact at the time of the abutment. Next, as shown in Fig. 7, when the abutment portion 134 of the linear damper 120 reaches the limit of elastic deformation, the relative displacement body 140 displaces within the inner chamber forming body 121 toward the rack housing 104 against the elastic force of the return elastic body 131. That is, the relative displacement body 140 is displaced while the first inner chamber forming wall 142 pushes the fluid 126 toward the valve support portion 123.

[0068] As a result, the direct-acting damper 120 generates a damping force by causing the fluid 126 in the first internal chamber 125a to flow toward the second internal chamber 125b while experiencing flow resistance through each of the three first flow control valves 127. When the first displacement limit defining portion 144 hits the valve support portion 123, the direct-acting damper 120 attenuates the impact at the time of the hit and the external force that displaces the relative displacement body 140 by elastic deformation due to compression of the first displacement limit defining portion 144.

[0069] Next, when the wheels 112 of the self-propelled vehicle are steered to the steering limit and the rack bar 103 reaches the displacement limit, and then the wheels 112 return to their original position, the abutting portion 134 of the linear damper 120 moves away from the rack housing 104, and then the inner chamber forming body 121 is displaced toward the rack housing 104 relative to the relative displacement body 140. That is, the inner chamber forming body 121 is displaced by the elastic force of the return elastic body 131 while the valve support portion 123 pushes the fluid 126 toward the second inner chamber forming wall 145.

[0070] As a result, in the direct-acting damper 120, the fluid 126 in the second inner chamber 125b flows toward the first inner chamber 125a through one second flow control valve 128 with extremely small flow resistance. In other words, the direct-acting damper 120 generates almost no damping force against external forces when the inner chamber forming body 121 returns to its original position. When the valve support portion 123 of the direct-acting damper 120 hits the second displacement limit defining portion 147, the second displacement limit defining portion 147 is elastically deformed by compression, thereby attenuating the impact (see FIG. 5).

[0071] When the abutment portion 134 of the linear damper 120 abuts against the rack housing 104, the linear damper 120 is separated from the rack housing 104 in an extremely short time due to the reaction force of this abutment or the driver's steering operation to resolve this abutment. As a result, the inner chamber forming body 121 is displaced toward the rack housing 104 while separated from the rack housing 104 (in other words, after being separated from the rack housing 104). As a result, the wheels 112 of the self-propelled vehicle return to their original positions.

[0072] As can be understood from the above explanation of the operating method, the linear damper 120 is configured to have an elastic body accommodating section 130 for accommodating the return elastic body 131 inside the inner chamber forming body 121 while being connected to the outside air, so that the return elastic body 131 can be easily accommodated in the elastic body accommodating section 130, thereby improving the ease of assembly and maintenance of the linear damper 120.

[0073] Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the scope of the present invention. In the description of each modification, the same parts as those in the above-described embodiment are designated by the same reference numerals, and redundant description will be omitted.

[0074] For example, in the above embodiment, the return elastic body 131 is configured as a wave spring. However, the return elastic body 131 may be configured as an elastic body that can apply an elastic force to the relative displacement body 140 and elastically absorb an external force acting on the relative displacement body 140. Therefore, the return elastic body 131 may be configured as a plurality of wave washers, coil springs, or elastomer.

[0075] In the above embodiment, the opening 130a of the elastic body accommodating portion 130 is formed with an inner diameter larger than the outer diameter of the return elastic body 131. However, the opening 130a of the elastic body accommodating portion 130 can also be formed with an inner diameter equal to or smaller than the outer diameter of the return elastic body 131. In this case, the return elastic body 131 should be made of a material such as an elastomer whose outer diameter is elastically deformable.

[0076] In the above embodiment, the linear damper 120 is configured to include the abutment portion 134. However, the linear damper 120 may be configured without the abutment portion 134.

[0077] In the above embodiment, the linear damper 120 is configured to include the elastic body receiver 133. However, the linear damper 120 may be configured without the elastic body receiver 133. In this case, the linear damper 120 may be configured so that the elastic force of the return elastic body 131 arranged in the elastic body accommodating portion 130 is received and supported by the second inner chamber forming wall 145 and the rack housing 104.

[0078] In the above embodiment, the abutment portion 134, the first displacement limit defining portion 144, and the second displacement limit defining portion 147 are each made of rubber. However, the abutment portion 134, the first displacement limit defining portion 144, and the second displacement limit defining portion 147 may be made of any elastic material that can elastically absorb an external force. In this case, the elastic material is preferably a viscoelastic material that deforms slowly in response to an external force to absorb impact or vibration. Furthermore, the viscoelastic material is preferably a viscoelastic material with a low rebound resilience, specifically, a viscoelastic material with a rebound resilience of 50% or less.

[0079] Therefore, the abutment portion 134, the first displacement limit defining portion 144, and the second displacement limit defining portion 147 can be made of a resin material such as a rubber material, a thermosetting elastomer material (e.g., vulcanized rubber, urethane rubber, silicone rubber, fluororubber, etc.) or a thermoplastic elastomer material (e.g., styrene-based, olefin-based, PVC-based, urethane-based, or amide-based resin). The abutment portion 134, the first displacement limit defining portion 144, and the second displacement limit defining portion 147 can also be made of a material other than an elastomer material, such as a metal leaf spring or coil spring, or a damper filled with a viscous fluid. The abutment portion 134, the first displacement limit defining portion 144, and the second displacement limit defining portion 147 can also be made by attaching a rigid resin plate or metal plate to the surface of an elastic body. As a result, the abutment portion 134, the first displacement limit regulating portion 144 and the second displacement limit regulating portion 147 can improve their abrasion resistance against objects that they abut, such as the rack housing 104, and can prevent damage.

[0080] In the above embodiment, the abutment portion 134, the first displacement limit defining portion 144, and the second displacement limit defining portion 147 are formed in an annular shape. However, the abutment portion 134, the first displacement limit defining portion 144, and the second displacement limit defining portion 147 can be formed in an annular shape other than a circle (including an oval), for example, a polygonal shape such as a triangle, a rectangle, a pentagon, or a hexagon, or an irregular shape. In this case, the abutment portion 134 and the second displacement limit defining portion 147 can also be formed in a conical shape like the first displacement limit defining portion 144. The abutment portion 134, the first displacement limit defining portion 144, and the second displacement limit defining portion 147 can also be formed by arranging small pieces in an annular shape.

[0081] In the above embodiment, the abutting portion 134 is configured with elasticity adjustment holes 134a. This allows the elasticity of the abutting portion 134 to be adjusted. Therefore, the number, position, and size of the elasticity adjustment holes 134a can be freely set in the abutting portion 134 according to the required elasticity. However, the elasticity of the abutting portion 134 can be adjusted by configuring the abutting portion 134 with at least one of a blind hole and a through hole. Furthermore, if the abutting portion 134 has the required elasticity without using the elasticity adjustment holes 134a, and the elasticity adjustment holes 134a are not necessary, the elasticity adjustment holes 134a can be omitted.

[0082] In the above embodiment, the abutment portion 134 is attached to the elastic body receiving body 133 by passing the bolt 135 through the abutment portion 134. However, the abutment portion 134 can be attached to the elastic body receiving body 133 by a method other than the bolt 135, such as by using an adhesive or welding.

[0083] In the above embodiment, the return elastic body 131 is configured so that a part of the outer periphery is covered by the cover body 132. However, the return elastic body 131 may be configured without the cover body 132.

[0084] Furthermore, in the above embodiment, the linear damper 120 is configured to include the first displacement limit defining portion 144 and the second displacement limit defining portion 147. This allows the linear damper 120 to attenuate the impact or external force when the relative displacement body 140 receives an external force and reaches a displacement limit position, and when the relative displacement body 140 reaches a displacement limit position that is the original position before receiving the external force. However, the linear damper 120 can also be configured without at least one of the first displacement limit defining portion 144 and the second displacement limit defining portion 147.

[0085] In the above embodiment, the linear damper 120 is configured to include the volume change compensation device 153. However, the linear damper 120 can be configured without the volume change compensation device 153 if the volume change of the fluid 126 can be ignored. Also, the linear damper 120 can have the volume change compensation device 153 provided outside the relative displacement body 140 or the inner chamber forming body 121.

[0086] In the above embodiment, the linear damper 120 is configured such that the relative displacement body 140 is connected to the rack bar 103 and the intermediate connector 105, respectively, and the inner chamber forming body 121 is brought into contact with or separated from the rack housing 104. However, the linear damper 120 can also be configured such that the inner chamber forming body 121 is connected to the rack housing 104, and the rack bar 103 or the intermediate connector 105 approaches or separates from the relative displacement body 140. In this case, the relative displacement body 140 is formed in a cylindrical shape so that the rack bar 103 passes through it, and abutment portions 134 are provided at portions where the rack bar 103 or a portion of the intermediate connector 105 directly connected to the rack bar 103 approaches and contacts it as the rack bar 103 moves back and forth. In the steering device 100, the linear damper 120 is provided in the rack housing 104, so that the weight of the rack bar 103 or the intermediate connector 105 (such as the tie rod 110 or the rack end 106) can be reduced.

[0087] In the above embodiment, the direct-acting damper 120 is configured to include four flow control valves, namely, three first flow control valves 127 and one second flow control valve 128. However, it goes without saying that the number and specifications of the flow control valves are appropriately set according to the specifications of the direct-acting damper 120. Furthermore, the flow control valves can also be provided in the relative displacement body 140 instead of or in addition to the inner chamber forming body 121.

[0088] In addition, in each of the above embodiments, the direct-acting damper 120 is applied to the steering device 100 having a mechanical configuration. However, it goes without saying that the direct-acting damper 120 can be applied to an electric power steering system using an electric motor, in addition to a hydraulic power steering system using hydraulic pressure.

[0089] In addition, in each of the above embodiments, the linear damper 120 is applied to the steering device 100. However, the linear damper 120 can be attached to a device or appliance other than the steering device 100, specifically, a door opening / closing mechanism, a mechanical device other than a self-propelled vehicle, an electrical device, an appliance, or furniture. [Explanation of symbols]

[0090] 100...Steering device, 101...Steering wheel, 102...Steering shaft, 102a...Pinion gear, 103...Rack bar, 103a...Rack gear, 104...Rack housing, 105...Intermediate connecting body, 106...Rack end, 107...Stud body, 107a...Ball portion, 108...Socket body, 108a...Socket main body, 108b...Connecting portion, 110...tie rod, 111...knuckle arm, 112...wheel, 120... Direct acting damper, 121... Inner chamber forming body, 122... Inner peripheral surface, 123... Valve support portion, 124... Seal ring, 125a... First inner chamber, 125b... Second inner chamber, 126... Fluid, 127... First flow control valve, 128... Second flow control valve, 130...elastic body accommodating portion, 130a...opening portion, 131...returning elastic body, 132...covering body, 133...elastic body receiving body, 133a...fitting portion, 134...butting portion, 134a...elasticity adjustment hole, 135...bolt, 140... relative displacement body, 141... inner chamber opposing portion, 142... first inner chamber forming wall, 143... seal ring, 144... first displacement limit determining portion, 145... second inner chamber forming wall, 145a... receiving recess, 146... seal ring, 147... second displacement limit determining portion, 148... rack end connecting portion, 149... rack bar connecting portion, 150...compensation device housing portion, 151...inner chamber communication passage, 152...atmosphere communication passage, 153...volume change compensation device.

Claims

1. an inner chamber forming body that is formed in a cylindrical shape and has an inner chamber that stores a fluid in a liquid-tight manner inside the cylindrically formed portion; a relative displacement body that is slidably fitted into the inner chamber forming body and displaces relative to the inner chamber forming body; a flow control valve provided in at least one of the inner chamber forming body and the relative displacement body, for restricting the flow of the fluid while allowing the fluid to flow, and the direct-acting damper is disposed between two objects that are linearly displaced relative to each other, and attenuates an external force received due to this relative displacement by restricting the flow of the fluid, a return elastic body that applies an elastic force to the relative displacement body to elastically receive the external force, The inner chamber forming body is The inner chamber forming body has an elastic body accommodating portion for accommodating the return elastic body in a state in which the return elastic body is communicated with the outside air, The returning elastic body is A linear damper characterized in that it is housed in the elastic body housing portion.

2. 2. The linear damper according to claim 1, The elastic body accommodating portion is A linear damper characterized in that it is formed in a state of communication with the outside air through an opening formed at one end of the inner chamber forming body which is large enough to allow the return elastic body to be inserted and removed.

3. The direct-acting damper according to claim 2, further comprising: A linear damper comprising an elastic body receiving body attached to the opening in the inner chamber forming body and receiving the elastic force of the return elastic body.

4. 4. The linear damper according to claim 3, The elastic body receiving body is A linear damper characterized in that it is positioned at a position where it will hit one of the two objects to be attached due to the relative displacement of the inner chamber forming body, and has an abutment portion made of an elastic body that elastically receives this abutment.

5. 5. The linear damper according to claim 1, The inner chamber comprises: a first internal chamber and a second internal chamber through which the fluid flows via the flow control valve; The relative displacement body is a first inner chamber forming wall that forms the first inner chamber while expanding or reducing the volume of the first inner chamber by the relative displacement of the relative displacement body; a second chamber forming wall that forms the second chamber while expanding or reducing the volume of the second chamber by the relative displacement of the relative displacement body, One of the first inner chamber forming wall and the second inner chamber forming wall is A linear damper, characterized in that the elastic body accommodating portion is formed by expanding or contracting the volume of the elastic body accommodating portion by the relative displacement of the relative displacement body.

6. a steering shaft formed in a rod-like shape and rotated by operation of a steering wheel; a rack bar formed in a rod-like shape, which converts the rotational motion of the steering shaft into a reciprocating motion in the axial direction and transmits the motion; an intermediate connector connected to each end of the rack bar and directly or indirectly connecting the wheels to be steered to each end of the rack bar; A steering device including a rack housing that covers the rack bar, A linear damper according to claim 1 is provided, The linear damper is A steering device characterized in that the steering device is provided between the rack housing and the rack bar or the intermediate connecting body, and attenuates impact from the wheels and / or impact due to inertial force from the steering shaft side.

7. 7. The steering device according to claim 6, the relative displacement body is connected to the intermediate connector, The inner chamber forming body is A steering device characterized in that the rack bar is formed so as to come into contact with or move away from the rack housing due to the reciprocating motion of the rack bar.

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