JP2013194763A - Fluid pressure shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid pressure shock absorbing technique capable of independently controlling a damping force at each of acceleration and deceleration by a dynamic load without complicating a structure.SOLUTION: In a fluid pressure shock absorber including a tank 10 communicating with an oil chamber B4 via a communication flow path 6 out of an oil chamber A2 and the oil chamber B4 formed separately by a piston valve 3 fixed to a piston rod 1 in an inside of a shell pipe 5, the communication flow path 6 is provided with a pressure dependence valve system 17 in parallel with a base valve 7, and the pressure dependence valve system 17 has such operating characteristics that a braking force is low in an initial stage on an acceleration side and is high in a transition stage to the latter half deceleration side, and operates so as to generate a secured damping force at a stop end in a final phase of a displacement while smoothing an initial displacement of an operational load of a vehicle body or the like.

Description

  The present invention relates to a fluid pressure shock absorber, for example, a technique suitable for a hydraulic shock absorber for passenger cars, trucks, and the like.

The hydraulic shock absorber is widely used as a means for suppressing or absorbing vibration or the like in a dynamic load such as a vehicle body of a vehicle.
In the prior art, there is a fixed flow path in which the cross section of the flow path through which the fluid passes is constant, a cross-section adjustable flow path in which the cross section of the flow path is variable from the outside as in Patent Document 1, and further in Patent Document 2 In addition, in the configuration in which the reservoir tank is connected to the cylinder, a structure is adopted in which a damping force (braking resistance) is generated by both the piston valve provided in the piston in the cylinder and the base valve provided in the reservoir tank. .

In this way, normally, the structure is such that a plurality of valves are sequentially opened as the pressure of the working fluid rises due to the action of a moving body load from the outside.
However, in such a conventional structure, when viewed at the same expansion and contraction speed, the damping force at the time of acceleration of the initial action of the moving body load cannot be reduced more than at the time of deceleration (when the moving body load disappears). There has been a technical problem that it is difficult to generate a firm damping force at the end of the displacement while smoothing the initial displacement of the operation load.

JP 2004-340358 A JP 2008-202699 A

  An object of the present invention is to provide a fluid pressure buffering technique capable of independently controlling the damping force at the time of acceleration and deceleration due to a moving body load without complicating the structure.

The present invention includes a plurality of fluid chambers in which a working fluid that flows according to a dynamic load is enclosed,
A first flow path communicating two adjacent fluid chambers;
Independently of the first flow path, a second flow path for communicating two adjacent fluid chambers;
A valve structure that is provided in the second flow path and closes the second flow path depending on a differential pressure between the working fluids of two adjacent fluid chambers;
A fluid pressure shock absorber is provided.

  According to the present invention, it is possible to provide a fluid pressure buffering technology capable of independently controlling the damping force at the time of acceleration and deceleration due to a moving body load without complicating the structure.

It is a figure which shows an example of a structure of the hydraulic shock absorber which is one embodiment of this invention. It is sectional drawing which expands and illustrates a part of structure of the hydraulic shock absorber which is one embodiment of this invention. It is sectional drawing which expands and illustrates a part of structure of the hydraulic shock absorber which is one embodiment of this invention. It is sectional drawing explaining the effect | action of the hydraulic shock absorber which is one embodiment of this invention. It is an expanded sectional view of the cylinder of the hydraulic shock absorber which is one embodiment of the present invention. It is a characteristic diagram which compared an example of the operation characteristic of the hydraulic shock absorber which is one embodiment of the present invention with the prior art. It is sectional drawing which shows the modification of the pressure dependent valve system which is one embodiment of this invention. It is sectional drawing which shows the modification of the pressure dependent valve system which is one embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram illustrating an example of a configuration of a hydraulic shock absorber according to an embodiment of the present invention.
2 and 3 are enlarged cross-sectional views illustrating a part of the configuration of the hydraulic shock absorber according to the embodiment of the present invention.

  As illustrated in FIG. 1, the hydraulic shock absorber according to the present embodiment includes a shell pipe 5 constituting a cylinder, a rod cover 5a for closing both ends of the shell pipe 5, and a bottom cover 5b.

  Inside the shell pipe 5, there is disposed a piston valve 3 that divides the internal space of the shell pipe 5 into an oil chamber A2 and an oil chamber B4. The piston valve 3 has a piston rod 1 penetrating the rod cover 5a. The inner end of is fixed.

  An upper bracket 1a and a lower bracket 5c are provided on the outer end portion of the piston rod 1 and the bottom cover 5b of the shell pipe 5, and can be fixed to an external moving body load or the like.

One end of the tank 10 is connected to the shell pipe 5 on the bottom cover 5b side.
The tank 10 is separated into a gas chamber 12 and an oil chamber C9 by a free piston 11, and the oil chamber C9 is connected to an oil chamber B4 of the shell pipe 5 via a communication channel 6 provided in the bottom cover 5b. Communicate.

  The oil chamber A2, the oil chamber B4, and the oil chamber C9 are filled with a working oil as a working fluid, and this working oil is constantly pressurized by the pressurized gas sealed in the gas chamber 12 of the tank 10, and the piston valve 3 The piston rod 1 fixed to is biased in the protruding direction.

  As illustrated in FIG. 2, the communication channel 6 provided in the bottom cover 5b that connects the shell pipe 5 and the tank 10 and that connects the oil chamber B4 and the oil chamber C9 branches into the branch path 6a and the branch path 6b. However, the base valve 7 is arranged in one branch path 6a.

The base valve 7 includes an extended base body 8f disposed so as to close the communication flow path 6, and a base bolt 8d mounted coaxially on the extended base body 8f.
A plurality of extension-side orifices 8g are provided in the periphery of the extension base body 8f.

A contraction-side port 8e communicating with the communication flow path 6 is formed through the base bolt 8d, and a valve body 8b having a different diameter is attached to the opening end of the contraction-side port 8e.
The valve body 8b is coaxially supported by the needle housing 8i, and is constantly urged in a direction to close the opening of the contraction side port 8e by the contraction high speed adjustment spring 8a via the needle housing 8i.

  The valve body 8b is formed with a valve body flow path 8c that is coaxial with the contraction side port 8e and penetrates in the axial direction. The valve body flow path 8c passes through a needle housing flow path 8j provided in the needle housing 8i. And communicated with the oil chamber C9.

  In the needle housing 8i, a shrinking low speed adjusting needle 8k is provided, and the opening of the valve body flow path 8c in the valve body 8b can be adjusted by being displaced from the outside via the adjusting screw 8m in the axial direction. It has become.

  The end of the shrinking high-speed adjustment spring 8a opposite to the valve body 8b is supported by a slide base 8n provided on the outer periphery of the needle housing 8i so as to be axially displaceable, and the axial position of the slide base 8n, That is, the urging force of the contraction high-speed adjustment spring 8a can be set by the adjustment screw 8p rotated from the outside.

  The base valve 7 generates an initial damping force according to the diameter of the compression side port 8e on the compression side where the hydraulic oil moves from the oil chamber B4 to the oil chamber C9. Accordingly, the valve body 8b opens and operates so as to relieve the damping force.

Further, on the extension side in the reverse direction, the leaf spring valve 8h is opened and the plurality of extension side orifices 8g are opened, thereby generating a damping force smaller than that on the compression side.
In the case of the present embodiment, as illustrated in FIGS. 2 and 3, a pressure-dependent valve system 17 is provided in parallel with the base valve 7 in the other branch path 6 b of the communication flow path 6.

That is, the communication flow path 6 branches into two branches 6a and 6b on the oil chamber C9 side, the base valve 7 is mounted on one side, and the pressure-dependent valve system 17 is mounted on the other side.
The pressure-dependent valve system 17 includes a cylindrical housing 18 in which a first communication hole 18 a communicating with the communication flow path 6 is formed in the axial direction, and attached to the opening of the oil chamber C 9 in the communication flow path 6. Yes.

  Inside the housing 18, a pressure-dependent valve 22 formed by penetrating a pressure-dependent valve channel 25 in the axial direction is accommodated so as to be displaceable in the axial direction. An O-ring 21 that slides with the inner peripheral portion of the housing 18 is attached to the outer peripheral portion of the pressure dependent valve 22.

  A cap 19 is provided at the opening end of the housing 18 opposite to the first communication hole 18a, and the pressure-dependent valve 22 is provided between the cap 19 and the pressure-dependent valve 22 at the opening of the first communication hole 18a. A spring 20 that biases in the direction of close contact is disposed.

  In the housing 18, a second communication hole 18 b is formed at a position on the back side of the pressure-dependent valve 22 that is in close contact with the opening of the first communication hole 18 a, and when the pressure-dependent valve 22 is separated from the cap 19, The communication channel 6 communicates with the oil chamber C9 through the first communication hole 18a, the pressure-dependent valve channel 25, and the second communication hole 18b.

  Thus, in the case of the pressure dependent valve system 17 of the present embodiment, as illustrated in FIG. 4, in a state where the pressure dependent valve 22 is in close contact with the opening of the first communication hole 18 a of the housing 18, The pressure-dependent valve 22 has a pressure-receiving surface A23 having a pressure-receiving area SA equal to the cross-sectional area of the first communication hole 18a. When the pressure-dependent valve 22 is separated from the first communication hole 18a, the pressure-dependent valve 22 has a cross-sectional area equal to the inner diameter of the housing 18. It has a pressure receiving surface B24 having an equal pressure receiving area SB (> SA). The operation of the pressure dependent valve system 17 will be described later.

On the other hand, the configuration of the piston valve 3 will be described with reference to FIG. FIG. 5 is an enlarged cross-sectional view of a cylinder constituted by the shell pipe 5.
The piston valve 3 fixed to the inner end of the piston rod 1 separates the oil chamber A2 and the oil chamber B4 by partitioning the internal space of the shell pipe 5 in an airtight manner as described above.

The piston valve 3 is provided with a plurality of orifice holes 3 a penetrating in the axial direction of the shell pipe 5 at desired intervals around the piston rod 1.
Openings on the oil chamber B4 side in the plurality of orifice holes 3a are covered and closed by a disc-shaped leaf spring 3b fixed to the piston rod 1.

The leaf spring 3b functions as a valve body that opens the orifice hole 3a in the direction in which the hydraulic oil flows from the oil chamber A2 to the oil chamber B4 and closes the orifice hole 3a in the reverse direction.
In the case of the present embodiment, a plurality of pressure dependent valve systems 14 are arranged between the plurality of orifice holes 3a.

  The pressure-dependent valve system 14 includes an orifice 14c penetrating the piston valve 3 in the axial direction, and a spherical valve body 14a and a spring 14b provided in an opening on the oil chamber B4 side of the orifice 14c.

At least one of the plurality of pressure dependent valve systems 14 is a dummy that includes only the orifice 14c and does not have a closing function.
As a result, when the piston rod 1 (piston valve 3) is displaced in the compression direction, the orifice hole 3a is closed by the leaf spring 3b, and the orifice 14c is closed by the pressure-dependent valve system 14 including the spherical valve element 14a. The pressure-dependent valve system 14 having a spherical valve body 14a and the like secures predetermined operating characteristics as will be described later, while passing from the oil chamber B4 to the oil chamber A2 through the orifice 14c of the dummy pressure-dependent valve system 14. The displacement of the piston rod 1 (piston valve 3) in the compression direction is made possible by the movement of the hydraulic oil to.

  The spherical valve body 14a is in contact with the leaf spring 3b by being biased by the spring 14b, and allows hydraulic oil to pass through the orifice 14c in the direction from the oil chamber A2 to the oil chamber B4. In the opposite direction, when the hydraulic oil passage speed is high, the spherical valve body 14a operates to close the orifice 14c against the urging force of the spring 14b.

  Further, the pressure receiving area from the oil chamber B4 side in the spherical valve body 14a is small in the initial state in contact with the leaf spring 3b (corresponding to the pressure receiving area SA described above) and large in the state separated from the leaf spring 3b (described above). Equivalent to the pressure receiving area SB).

Hereinafter, an example of the operation of the present embodiment will be described.
For example, description will be made by paying attention to the pressure dependent valve 22 disposed between the oil chamber B4 and the oil chamber C9 illustrated in FIG.

  When the piston valve 3 operates in a direction (compression side) for pushing out the hydraulic oil from the oil chamber B4 of the shell pipe 5 to the oil chamber C9 of the tank 10, the pressure dependence set in advance in the pressure dependence valve 22 of the present embodiment. A differential pressure ΔP is generated between the oil chamber B4 and the oil chamber C9 communicated via the communication flow path 6 in accordance with the diameter of the valve flow path 25, the diameter of the compression side port 8e in the base valve 7, and the like.

That is, a differential pressure is generated across the pressure dependent valve 22. When accelerating from the top dead center to the compression side, the operation starts from a low pressure,
The area of the pressure receiving surface A23 of the pressure dependent valve 22 is the pressure receiving area SA,
The area of the pressure receiving surface B24 of the pressure dependent valve 22 is the pressure receiving area SB,
The differential pressure between oil chamber B4 and oil chamber C9 is ΔP,
The pressing force acting on the pressure dependent valve 22 from the hydraulic oil is F22,
The urging force of the spring 20 is F20,
Then,
F22 = pressure receiving area SA × ΔP,
Does not change until the pre-compression load (biasing force F20) on the pressure-dependent valve 22 of the spring 20 is exceeded.

  When F22 exceeds this precompression load (biasing force F20) (F22> F20), the pressure-dependent valve 22 is displaced in a direction away from the first communication hole 18a against the spring 20, and the oil of the pressure-dependent valve 22 is displaced. The pressure receiving area on the chamber B4 side is increased, and the hydraulic oil presses the spring 20 with a larger force (F22).

  Due to this pressing force F22 (> F20), the pressure-dependent valve 22 and the cap 19 are brought into close contact with each other, the pressure-dependent valve channel 25 which was effective in the initial state is closed, and a larger differential pressure is generated (characteristic curve portion C1 described later). ).

After accelerating to a certain point (for example, the center of the stroke), the piston valve 3 decelerates and converges to zero speed.
F22 = pressure receiving area SB × ΔP,
Until the pressure is less than the compression load (biasing force F20) of the spring 20 (F22 <F20), the pressure dependent valve passage 25 of the pressure dependent valve 22 is not opened again. For this reason, a large damping force is maintained up to the convergence end of the piston valve 3 (characteristic curve portion C2 described later).

As a result, an operation characteristic that generates a greater damping force when decelerating than when accelerating is obtained by the pressure-dependent valve system 17 of the present embodiment.
FIG. 6 is a characteristic diagram comparing an example of operation characteristics of the pressure-dependent valve system 17 of the present embodiment as described above with the prior art.

FIG. 6 shows characteristics when a compression / extension load is applied with a sine wave having the maximum acceleration at the center of the stroke.
In the case of the conventional base valve 7 alone, as shown by the broken line, the characteristic from the initial stage to the final stage (between the top dead center / bottom dead center of the piston valve 3) It is almost symmetrical.

  On the other hand, when the pressure-dependent valve system 17 of the present embodiment is provided, as shown by the solid line in FIG. 6, on the compression side, a damping force is generated at the center of the stroke (that is, the maximum acceleration portion). Asymmetrical operating characteristics such as an increasing characteristic curve portion C1 and a characteristic curve portion C2 that maintains a large braking force until the end of the stroke are obtained.

  In other words, according to the pressure-dependent valve system 17 of the present embodiment, a fluid pressure buffering technology capable of independently controlling the damping force at the time of acceleration and deceleration by a moving body load without complicating the structure is provided. it can.

  As a result, for example, when viewed at the same expansion / contraction speed, the damping force at the initial acceleration (first half of the stroke) of the moving body load acting on the piston valve 3 via the piston rod 1 is reduced to that at the time of deceleration (the second half of the moving body). (Characteristic curve portion C1), and smoothing the initial displacement of the vehicle and generating a firm damping force at the end of the displacement (stop end side) (characteristic curve portion) C2).

As illustrated in FIG. 5, this characteristic can also be obtained in the pressure-dependent valve system 14 of the piston valve 3 provided between the oil chamber A2 and the oil chamber B4.
That is, on the compression side where the piston valve 3 moves to the oil chamber B4 side, the orifice hole 3a is closed by the leaf spring 3b, and the spherical valve body 14a is in close contact with the leaf spring 3b (the pressure receiving area SA described above). The hydraulic oil passes through the orifice 14c.

  At this time, at the initial stage of acceleration, since the spherical valve element 14a is opened at a position in close contact with the leaf spring 3b, a relatively small braking force is generated (characteristic curve portion C1), and when the acceleration increases, the spherical valve element 14a The spring 14b is separated from the leaf spring 3b against the urging force of the spring 14b (a state equivalent to the above-described pressure receiving area SB), is in close contact with the orifice 14c and closes, and generates a large braking force.

  As described above, since the pressure receiving area of the spherical valve element 14a is large in the state of being separated from the leaf spring 3b (the condition of the pressure receiving area SB> SA), the spherical valve element 14a remains in the orifice even if deceleration is started in the latter half of the stroke. The state where 14c is closed is maintained (characteristic curve portion C2).

Thereby, also in the pressure dependence valve system 14 provided in the piston valve 3, the effect similar to the above-mentioned pressure dependence valve system 17 is acquired.
In the above description, an example in which the pressure-dependent valve system 17 and the pressure-dependent valve system 14 are provided is shown, but only one of them may be provided.

Next, a modification of the present embodiment will be described. 7 and 8 are cross-sectional views showing modifications of the pressure dependent valve system 17 of the present embodiment.
In the pressure-dependent valve system 17A of this modification, the opening degree of the pre-compression load adjusting screw 28 that supports the spring 20 and the pressure-dependent valve passage 25 is adjusted instead of the cap 19 in the pressure-dependent valve system 17 described above. The adjustment needle 26 is provided.

  The adjustment needle 26 is supported on the back side by an adjustment screw 29 screwed into the inner periphery of a cylindrical precompression load adjustment screw 28, and the adjustment screw 29 is rotated by an adjustment dial 27 exposed to the outside. ing.

  That is, in the pressure-dependent valve system 17A, the cross-sectional area of the pressure-dependent valve flow path 25 provided in the pressure-dependent valve 22 that controls the load at which the valve is closed is moved from the outside by moving the adjustment needle 26 with the adjustment dial 27. It can be adjusted.

Further, the precompression load (biasing force F20) of the spring 20 that determines the timing for opening and closing the valve can also be adjusted by the precompression load adjusting screw 28.
Thereby, in the pressure-dependent valve system 17A of the modified example, in addition to the effects in the configuration of the pressure-dependent valve system 17 described above, each of the characteristic curve portion C1 and the characteristic curve portion C2 in the characteristic curve illustrated in FIG. Can be appropriately adjusted according to the type of moving body load and the like.

  In the above-described example, the pressure-dependent valve flow path 25 is exemplified by a structure that is closed by the cap 19 or the adjustment needle 26. However, a micro flow path that communicates with the closed pressure-dependent valve flow path 25 is provided. It is also possible to provide it. Furthermore, the cross-sectional area of the microchannel after the valve is easily closed by applying the designs of FIGS. 7 and 8 can also be adjusted from the outside.

Further, instead of the base valve 7, a simple orifice may be provided in the branch path 6 a of the communication flow path 6.
Needless to say, the present invention is not limited to the configuration exemplified in the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

1 Piston rod 1a Rod bracket 2 Oil chamber A (fluid chamber)
3 Piston valve 3a Orifice hole (first flow path)
3b Leaf spring 4 Oil chamber B (fluid chamber)
5 Shell pipe 5a Rod cover 5b Bottom cover 5c Bracket 6 Communication flow path 6a Branch path (first flow path)
6b Branch path (second flow path)
7 Base valve 8a Contraction high speed adjustment spring 8b Valve element 8c Valve element flow path 8d Base bolt 8e Contraction side port 8f Base body 8g Extension side orifice 8h Leaf spring valve 8i Needle housing 8j Needle housing flow path 8k Contraction low speed adjustment needle 8m Adjustment screw 8n Slide base 8p Adjustment screw 9 Oil chamber C (fluid chamber)
10 Tank 11 Free Piston 12 Gas Chamber 14 Pressure Dependent Valve System (Valve Structure)
14a Spherical valve body (pressure control structure)
14b Spring 14c Orifice (second flow path)
17 Pressure dependent valve system (valve structure)
17A Pressure dependent valve system (valve structure)
18 Housing 18a First communication hole 18b Second communication hole 19 Cap 20 Spring (biasing means)
21 O-ring 22 Pressure dependent valve (pressure control structure) (valve)
25 Pressure-dependent valve flow path 26 Adjustment needle (flow path cross-section adjustment structure)
27 Adjustment dial (Flow path cross-section adjustment structure)
28 Pre-compression load adjusting screw (closing pressure adjusting structure)
29 Adjustment screw (Flow path cross-section adjustment structure)
A23 Pressure receiving surface B24 Pressure receiving surface C1 Characteristic curve portion C2 Characteristic curve portion

Claims (7)

A plurality of fluid chambers in which a working fluid flowing by a moving body load is enclosed;
A first flow path communicating two adjacent fluid chambers;
Independently of the first flow path, a second flow path for communicating two adjacent fluid chambers;
A valve structure that is provided in the second flow path and closes the second flow path depending on a differential pressure between the working fluids of two adjacent fluid chambers;
A fluid pressure shock absorber characterized by comprising: The fluid pressure shock absorber according to claim 1.
The fluid pressure buffer, wherein the valve structure includes a pressure control structure for differentiating the differential pressure that opens the differential pressure that closes the second flow path of the valve structure. The fluid pressure shock absorber according to claim 1 or 2,
A fluid pressure shock absorber having a closing pressure adjusting structure capable of adjusting the differential pressure for closing the second flow path of the valve structure from the outside. The fluid pressure shock absorber according to claim 1 or 2,
A fluid pressure shock absorber having a flow path cross-sectional adjustment structure capable of adjusting a cross-sectional area of the second flow path from the outside in a state where the valve structure is opened. The fluid pressure shock absorber according to claim 1.
The valve structure is
A housing formed with a first communication hole and a second communication hole communicating with the second flow path;
A valve body housed in the housing, having a diameter larger than that of the first communication hole and having a through hole communicating with the first communication hole;
Urging means for urging the valve body in a direction to press against the opening of the first communication hole in the housing;
A block that closes the second flow path that is disposed to face the first communication hole across the valve body and communicates with the through-hole of the valve body that approaches the biasing force of the biasing means. Members,
A fluid pressure shock absorber. The fluid pressure shock absorber according to claim 5,
The valve structure is
The fluid pressure shock absorber further comprises a closing pressure adjusting structure for adjusting the urging force of the urging means for urging the valve body from the outside. The fluid pressure shock absorber according to claim 5,
The valve structure is
The fluid pressure shock absorber further includes a closed flow path cross-sectional adjustment structure that changes the relative position of the closing member with respect to the valve body from the outside.