JP2006144986A - Hydraulic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic shock absorber having simple construction with a less number of components for improving machining, assembling efficiency and economy to allow independent setting of pressure receiving areas on extension and compression stroke sides while increasing a damping force variable range in extension and compression strokes. <P>SOLUTION: The hydraulic shock absorber comprises a spool 8 for closably seating a damping force adjusting mechanism 4 on a disc 18 provided on the way of a main passage C, a spring 9 provided on the back of the spool 8 for thrusting the spool 8 against a seat portion 18a of the disc 18, a solenoid S opposed to the spring 9, a compression side pressure receiving chamber 6 formed on the back of the spool 8 in communication with a second oil chamber B, an extension side pressure receiving chamber 7 formed in the spool 8 in opposition to the compression side pressure receiving chamber 6 and in communication with a first oil chamber A, and a reaction pin 10 slidably inserted in the extension side pressure receiving chamber 7 and energized to the side of the disc 18. Damping force is adjusted while controlling the cracking pressure of the spool 8 corresponding to a current applied to the solenoid S. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a damping force adjusting hydraulic shock absorber used as a suspension device for a vehicle such as an automobile.

  As this type of hydraulic shock absorber, for example, the one disclosed in Patent Document 1 is disclosed.

  This hydraulic shock absorber includes a piston rod movably inserted into a cylinder via a piston, a working chamber as first and second oil chambers partitioned via a piston in the cylinder, and a piston and a piston rod. A main passage formed to communicate with the first and second working chambers; a damping valve provided in the middle of the main passage; and a damping force adjusting mechanism provided in series with the damping valve in the middle of the main passage; It consists of

  The damping force adjusting mechanism opens and closes the main passage, a spool type valve element, a spring element and a drive element provided on the back of the valve element to urge the valve element in a closing direction, and opposed to the spring element. A solenoid that performs pilot pressure on the back surface of the valve body, an extension side control chamber that serves as a pilot chamber, a pilot passage that is formed in the valve body and communicates the control chamber to the working chamber side, and the spring element in the closing direction. A poppet-type valve element that opens and closes the pilot passage while being energized.

  With the above configuration, the valve body is directly biased in the closing direction by the spring element, and this valve body is biased by the pressure of the damping fluid in the working chamber corresponding to the spring element.

In the expansion stroke, the spool type valve element is energized by the pilot pressure in the control chamber set by the poppet type valve element. The damping force can be varied according to the energization current to the solenoid by acting in the direction of decreasing the power.
Japanese Patent Laid-Open No. 11-72133 (FIG. 2)

  In the above-described conventional hydraulic shock absorber, a pilot passage is formed in a spool-type valve body, a poppet-type valve element is provided in the pilot passage so as to be openable and closable, and a drive element is provided at the back of the spool-type valve body. Therefore, the structure of the damping force adjuster is complicated and inferior in workability and assembly.

  In addition, the spool type valve element that opens and closes the main passage is energized by the pilot pressure of the control chamber in the extension stroke, and is directly energized by the spring element in the pressure stroke, so the pilot pressure is increased in the extension stroke. There is only one control chamber that works.

  For this reason, the damping force variable range in the pressure stroke depends only on the spring element, and there is a problem that the adjustment range cannot be increased.

  Therefore, the object of the present invention is that the number of parts is small, the structure is simple, the workability, assemblability and economy are excellent, and not only the extension stroke, but also the damping force variable range can be increased in the compression stroke. It is an object of the present invention to provide a hydraulic shock absorber capable of independently setting the pressure receiving area.

  In order to achieve the above object, the means of the present invention includes a piston rod 3 that is movably inserted into the cylinder 1 via the piston 2, and first and second oils that are partitioned in the cylinder via the piston 2. A main passage C formed in the chambers A and B, the piston 2 and the piston rod 3 and communicating with the first and second oil chambers A and B; a damping valve 5 provided in the middle of the main passage; Similarly, in a hydraulic shock absorber comprising a damping force adjusting mechanism 4 provided in series with the damping valve 5 in the middle of the main passage C, the damping force adjusting mechanism 4 is opened and closed to a disk 18 provided in the middle of the main passage C. A spool 8 that is freely seated, a spring 9 that is provided on the back portion of the spool 8 and presses the spur 8 against the seat portion 18a of the disk 18, a solenoid S that faces the spring 9, and a rear surface of the spool 8. A pressure side pressure receiving chamber 6 that is formed and communicates with the second oil chamber B, and an expansion side pressure receiving chamber 7 that is formed in the spool 8 while facing the pressure side pressure receiving chamber 6 and communicates with the first oil chamber A. And a reaction force pin 10 that is slidably inserted into the extension side pressure receiving chamber 7 and is urged toward the disk 18, and the spool 8 according to the current applied to the solenoid S. The damping force is adjusted while adjusting the cracking pressure.

  According to the present invention, a poppet type valve element is not used as a damping force adjusting mechanism, but a single spool and a reaction force pin in the spool are used. Small number of points, simple structure, excellent workability, assembly, and economy.

  Furthermore, since the cracking pressure of the spool is controlled by a single solenoid, the damping force variable range can be increased not only in the extension stroke but also in the pressure stroke, and the variable range of the extension stroke and the pressure stroke can be set independently.

  As shown in FIG. 1, a hydraulic shock absorber according to the present invention is divided into a cylinder 1, a piston rod 3 movably inserted into the cylinder 1 via a piston 2, and a cylinder 1 via a piston 2. First and second oil chambers A. B, a gas chamber G defined in the cylinder 1 via a free piston F, and a piston valve VA incorporated in the piston 2 and the piston rod 3.

  As shown in FIG. 2 showing the main part of the hydraulic shock absorber incorporating the piston valve VA, the hydraulic shock absorber includes a piston rod 3 that is movably inserted into the cylinder 1 via the piston 2, and a cylinder 1 The first and second oil chambers A and B partitioned by the piston 2 and the main passage C formed in the piston 2 and the piston rod 3 and communicating with the first and second oil chambers A and B. The damping valve 5 provided in the middle of the main passage C, and the damping force adjusting mechanism 4 provided in series with the damping valve 5 in the middle of the main passage C.

  The damping force adjusting mechanism 4 is provided on the disk 18 provided in the middle of the main passage C so as to be openable and closable. The spool 8 is provided on the back of the spool 8 and presses the spool 8 against the seat portion 18a of the disk 18. A spring 9, a solenoid S opposed to the spring 9, a pressure side pressure receiving chamber 6 formed on the back surface of the spool 8 and communicating with the second oil chamber B, and the pressure side pressure receiving chamber 6 opposed to the inside of the spool 8. The extension side pressure receiving chamber 7 formed in communication with the first oil chamber A, and the reaction force pin 10 slidably inserted into the extension side pressure receiving chamber 7 and urged toward the disk 18 side. The damping force is adjusted while adjusting the cracking pressure of the spool 8 according to the current applied to the solenoid S.

  In this case, the pressure side pressure receiving chamber 6 and the expansion side pressure receiving chamber 7 communicate with the second and first oil chambers B and A through pressure introducing holes 11 and 12 formed in the main body 8a of the spool 8, respectively.

  Further, the reaction force pin 10 is pressed through a spring 13 inserted into the extension side pressure receiving chamber 7 and is in contact with the upper surface of the disk 18.

Further, as shown in FIG. 3, when the diameter D1 of the main body 8a of the spool 8 is D2, the sheet diameter of the disk 18 with respect to the spool 8 is D2, and the diameter of the reaction force pin 10 is D3, D2> D1, D3 ² > D2 ² -D1 is set to have a ^second relationship.

  The solenoid S has a stator 15 and a coil 16 provided on the outer periphery of the stator 15.

  Further, a hollow disk 18 having a hole 53 formed in the piston 2 is provided, and a lower end sheet surface of the spool 8 is seated on an annular sheet portion 18a of the disk 18 so as to be freely opened and closed.

  Hereinafter, a more specific description will be given based on FIG.

  Although FIG. 1 shows a single cylinder type embodiment, a hydraulic shock absorber having a double cylinder structure may be used.

  Further, the other end of the piston rod 3 is only a piston that divides the oil chamber, and a passage that communicates the oil chamber A and the oil chamber B is formed outside the cylinder 1. A certain valve may be provided.

  A housing 20 is joined to the tip of the piston rod 3, and a cap 21, a guide 22, a non-magnetic filler pipe 23, a guide 24, and a disk 18 are inserted into the housing 20, and the piston 2 and the housing 20 are fastened with screws. Thus, each component is fixed.

  In addition, each fitting portion of the guide 22, the filler pipe 23, and the guide 24 is configured as a guide assembly by means such as welding so that airtightness can be ensured.

  The cylindrical portions of the housing 20 and the guide 24 are provided with a passage 25 and a passage 26 constituting the main passage C, and the pressure side receiving chamber 40 and the lower chamber 41 on the disk 18 and the central hole 53 are formed in the main portion C. A passage C is formed.

  A rebound stopper 50 centered by the piston rod 3 is fitted on the upper portion of the housing 20, and a groove is radially carved on the upper end surface of the housing 20. A passage 27 is formed.

  The housing 20 is provided with an air vent passage 28 communicating with the interior of the housing 20 from the passage 27, and the cap 21 communicates with a small hole 31 provided in the guide 22 and an air vent pilot passage 30. Similarly, an air vent passage 29 is provided.

  These air vent passages 27, 28, 29, 30 and the small hole 31 are for removing air accumulated in the pressure side pressure receiving chamber 6 during assembly, and the small hole 31 has a very small inner diameter and a damping force. Has almost no effect.

  Sixteen coils connected to the harness 36 are fitted on the outside of the guide assembly, and a notch plate 54 provided with a notch serving as an oil passage and a spring 9 are inserted inside the guide assembly.

  The spool 8 includes a step-shaped spool body 8 a having a small-diameter portion and a large-diameter portion, and an extension-side pressure chamber 34 communicating with the passage 26 is formed by fitting with the guide 24.

  The main body 8a of the spool 8 is formed with a pressure side pressure receiving chamber 6 opened upward, and a pressure introduction hole 11 that communicates the pressure side pressure receiving chamber 6 with the pressure side pressure receiving chamber 40, the hole 53, and the chamber 41 to the second oil chamber B side. ing.

  Similarly, the expansion side pressure receiving chamber 7 and the pressure introducing hole 12 that communicates with the expansion side pressure chamber 34 are formed in the lower portion of the main body 8 a of the spool 8. A pressure pin 10 and a spring 13 are inserted into the extension side pressure receiving chamber 40.

  The piston 2 has a band 49 made of Teflon (registered trademark) or other synthetic resin wound around a portion sliding with the cylinder 1, and a soft damping valve 5 is fixed inside by caulking. A shim, a special washer with a part of the outer periphery cut off, a disc-shaped center, a support, a valve stopper, and a cap with a part of the outer periphery cut off are fixed by caulking on the disk 52.

  A plurality of leaf valves 51 whose outer periphery is guided by a cap are sandwiched between the disc 52 and the support, and the disc 52 is provided with a hole 55 constituting a main passage through which oil flows.

  Although not shown in the figure, an orifice that bypasses the leaf valve 51 may be provided depending on the required characteristics, as with a normal shock absorber valve. Where the oil leaks, it is sealed with O-rings O1, O2, and O3.

  Next, the operation will be described. First, the operation when the coil is not energized will be described. In the extending stroke, the pressure in the expansion side pressure receiving chamber 34 is passed through the communication hole 25, the annular chamber 44, and the communication hole 26. The pressure in the first oil chamber A is the same as that in the first oil chamber A, and the pressure in the extension side pressure receiving pressure 7 is also the same as the pressure in the extension side pressure receiving chamber 34, that is, the oil chamber A through the pressure introducing hole 12.

  On the other hand, the pressure in the pressure side pressure receiving chamber 6 communicates with the pressure side pressure receiving chamber 40 through the pressure introducing hole 11 and is in a downstream pressure state. At that time, as shown in FIG. Considering the state, the upstream pressure Pr acts on the area of the annular portion having the seat diameter D2 and the diameter D1 of the main body 8a of the spool 8 in the direction of pressing the spool 8 against the seat portion 18a.

On the other hand, the pressure acting in the extension side pressure receiving chamber 7 acts in a direction in which the spool 8 is separated from the seat portion 18a with the reaction force pin diameter D3 as the pressure receiving area. A force of Pr · π · (D3 ² −D2 ² + D1 ² ) / 4 is acting in the direction away from the portion 18a.

When the upstream pressure Pr is increased by an external force and Pr · π · (D3 ² −D2 ² + D1 ² ) / 4> F (F is the urging force of the spring A), the spool 8 deflects the spring 9 and the seat portion The oil in the oil chamber A passes through the communication hole 25, the annular chamber 44, the communication hole 26, the expansion side pressure chamber 34, the opening of the seat portion 18 a, the pressure side pressure receiving chamber 40, and the communication hole 53. At this time, the opening of the sheet portion 18a becomes a throttle and generates a pressure difference.

  Further, the inner peripheral side of the leaf valve 51 of the soft damping force valve 5 is bent from the chamber 41 and flows into the second oil chamber B. At this time, by passing through the soft damping force valve 5, the chamber 41 and the oil chamber B A pressure chamber is created between the two chambers, and the sum of the pressure differences between the two chambers becomes the differential pressure between the oil chamber A and the oil chamber B, and an extension side damping force is generated to pull down the piston rod 3.

  Next, in the pressure stroke, the pressure in the pressure side pressure receiving chamber 6 is the same as the pressure in the chamber 41 serving as the upstream pressure Pr via the pressure introducing hole 11.

  On the other hand, the pressure in the expansion side pressure receiving chamber 7 is in the pressure state of the oil chamber A that is downstream pressure through the communication hole 25, the annular chamber 44, and the communication hole 26. At this time, as shown in FIG. Assuming that the pressure is the reference state, the upstream pressure Pc acts on the circular area of the seat diameter D2 in the direction of separating the spool 8 from the seat portion 18a, and the pressure used in the pressure side pressure receiving chamber 6 is the diameter of the spool body 8a. The circular portion of D1 serves as a pressure receiving area, and acts in a direction to press the spool 8 against the seat portion 18a.

Accordingly, a force of Pc · π · (D2 ² -D1 ² ) / 4 is applied to the spool 8 in a direction away from the sheet surface.

When the upstream pressure Pc rises due to the external force and Pc · π · (D2 ² −D1 ² ) / 4> F (F is the urging force of the spring 9), the spool 8 deflects the spring 9 from the seat portion 18a. The oil in the chamber 41 opens to the oil chamber A through the communication hole 53, the pressure side pressure receiving chamber 40, the opening of the seat portion 18 a, the extension side pressure chamber 34, the communication hole 26, the annular chamber 44, and the communication hole 25. At this time, a pressure difference is generated by the opening of the seat portion 18a. On the other hand, the oil 41 flows into the chamber 41 by bending the outer peripheral side of the leaf valve 51 of the soft damping force valve 5 from the oil chamber B.

  At this time, a pressure difference is generated between the oil chamber B and the chamber 41 by passing through the soft damping force valve 5, and the sum of both pressure differences becomes a differential pressure between the oil chamber B and the oil chamber A, and the piston A compression side damping force is generated to push up the rod 3.

  In the present state in which the coil 16 is not energized in both the extension stroke and the pressure stroke, the urging force of the spring 9 is in the maximum state, and thus this state has the highest hard damping force.

  Next, a case where a coil current is passed will be described. When a current is passed through the coil 16, a magnetic force is generated around the coil 16, and the magnitude of the magnetic force varies depending on the magnitude of the current.

  The magnetic force is generated in a loop shape passing through the guide 22, the cap 21, the housing 20, the guide 24, and the spool 8, and there is a gap between the guide 22 and the spool 8, so the spool 8 is attracted to the guide 22 by the magnetic force. So that the suction force works.

  This attraction force acts in the direction in which the spring 9 is contracted, but since the initial force is acting on the spring 9, the spring 9 does not bend while the attraction force does not exceed the initial force, and the attraction force is drawn from the initial force. The reduced force acts as an urging force that presses the spool 8 against the sheet portion 18 a of the disk 18.

  That is, in the case of non-energization, it is the same as reducing the urging force of the spring 9, and both the decompression and the damping force are low.

  As can be seen from the above, the lowest damping force is obtained when the attraction force is equal to the current value equal to the initial force of the spring 9, and the highest damping force is obtained when the current is not energized.

  By continuously changing the current value during this period, the damping force can be continuously changed accordingly.

It is a vertical front view of the hydraulic shock absorber according to the present invention. It is a partial expanded sectional view of the principal part in the piston valve part of FIG. It is a partial expanded sectional view which shows the dimensional relationship of the spool part of FIG. FIG. 3 is a partial enlarged cross-sectional view of a spool portion during the extending stroke of FIG. 2. FIG. 3 is a partial enlarged cross-sectional view of a spool portion during the pressure stroke of FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 3 Piston rod 4 Damping force adjustment mechanism 5 Damping valve 6 Pressure side pressure receiving chamber 7 Extension side pressure receiving chamber 8 Spool 9 Spring 10 Pressure pin 18 Disc 18a Seat part A, B Oil chamber C Main passage S Solenoid

Claims (4)

A piston rod 3 movably inserted in the cylinder 1 via the piston 2, first and second oil chambers A and B partitioned in the cylinder via the piston 2, and in the piston 2 and the piston rod 3 A main passage C that is formed and communicates with the first and second oil chambers A and B, a damping valve 5 provided in the middle of the main passage, and in series with the damping valve 5 in the middle of the main passage C. In the hydraulic shock absorber comprising the damping force adjusting mechanism 4 provided on the spool 8, the damping force adjusting mechanism 4 is provided on the disc 18 provided in the middle of the main passage C so as to be openable and closable, and provided on the back of the spool 8. And a pressure side that is formed on the back surface of the spool 8 and communicates with the second oil chamber B. The spring 9 presses the spur 8 against the seat portion 18a of the disk 18. A pressure chamber 6, an extension side pressure receiving chamber 7 that is formed in the spool 8 while facing the pressure side pressure receiving chamber 6 and communicates with the first oil chamber A, and is slidable in the extension side pressure receiving chamber 7. It is composed of a reaction force pin 10 that is inserted and urged toward the disk 18, and adjusts the damping force while adjusting the cracking pressure of the spool 8 according to the current applied to the solenoid S. And hydraulic shock absorber. The pressure side pressure receiving side chamber 6 and the extension side receiving chamber 7 communicate with the second and first oil chambers B and A via pressure introducing holes 11 and 12 formed in the main body 8a of the spool 8, respectively. The hydraulic shock absorber described. The hydraulic shock absorber according to claim 1 or 2, wherein the reaction force pin (10) is pressed through a spring (13) inserted into the expansion side pressure receiving chamber (7) and is in contact with the upper surface of the disk (18). When the diameter of the main body 8a of the spool 8 is D1, the sheet diameter of the disk 18 with respect to the spool 8 is D2, and the diameter of the reaction pin 10 is D3, the relation of D2> D1, D3 ² > D2 ² -D1 ² is satisfied. The hydraulic shock absorber according to claim 1, 2, or 3.

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