VALVE AND SHOCK ABSORBER WITH THE SAME

Abstract

An object of the invention is to provide a control valve that suppresses the transmission of vibrations generated in a pilot valve to a main valve. In this invention, a shock absorber 100 is equipped with the control valve 113. The control valve 113 includes: a main valve 18 for controlling a flow rate of hydraulic oil; a pilot valve 19 for opening and closing the main valve 18 by controlling a pressure in a back pressure chamber 6 arranged on a back side of the main valve 18; a communication passage 5 that enables communication between the pilot valve 19 and the back pressure chamber 6; and a resonance structure (branch passage 41, resonance chamber 42) that suppresses pressure vibrations transmitted by the hydraulic oil in the communication passage 5.

Description

Technical area

[0001] The present invention relates to a valve having a main valve and a pilot valve, and to a shock absorber equipped with the valve. background

[0002] For example, Patent Literature 1 describes a technology for a shock absorber that controls damping force. Patent Literature 1 describes a configuration for improving vehicle stability and ride comfort by actively controlling the damping force of a vehicle-mounted shock absorber. This shock absorber is equipped with a damping force changer in an internal hydraulic circuit, which controls the flow of hydraulic oil and adjusts the damping force. Citation listPatent literature

[0003] Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2016-7918 Overview of the inventionTechnical problem

[0004] The damping force changer in Patent Literature 1 changes the pressure upstream of the pilot valve according to the valve opening and transmits this pressure to the back pressure chamber of the main valve via a connecting channel, thereby adjusting the opening degree of the main valve and controlling the flow of hydraulic oil. Since this damping force changer is part of the shock absorber's hydraulic circuit, the damping force of the shock absorber is adjusted by controlling the flow of hydraulic oil.

[0005] However, in Patent Literature 1, the pilot valve and the main valve are only connected by the connecting channel, and vibrations that may occur in the pilot valve may be transmitted to the main valve, resulting in abnormal noise. Patent Literature 1 does not consider the suppression of vibrations transmitted from the pilot valve to the main valve.

[0006] An object of the present invention is to provide a valve that suppresses the transmission of vibrations generated in a pilot valve to a main valve, and a shock absorber equipped with this valve. Solution to the problem

[0007] To achieve the above-mentioned object, as one aspect, a shock absorber of this invention is equipped with a control valve that controls the damping force by adjusting the pressure of the hydraulic oil flowing through the control valve. In the shock absorber, the control valve includes: a main valve for controlling a flow of the hydraulic oil; a pilot valve for opening and closing the main valve by controlling a pressure in a back pressure chamber located at a rear side of the main valve; a communication passage that enables communication between the pilot valve and the back chamber; and a resonance structure that suppresses pressure vibrations transmitted by the hydraulic oil in the communication passage. Advantageous effects of the invention

[0008] According to the present invention, it is possible to provide a valve that suppresses the transmission of vibrations generated in a pilot valve to a main valve, and a shock absorber equipped with the valve. Brief description of the drawings Fig. 1 is a cross-sectional view illustrating the schematic configuration of a shock absorber 100 according to an embodiment of the present invention. Fig. Fig. 2 is a cross-sectional view illustrating the schematic configuration of a typical control valve 113' (comparative example). Fig. 3 is a cross-sectional view illustrating the schematic configuration of a control valve 113 according to a first embodiment of the present invention. Fig. Fig. 4 is a bottom view of a branch channel disc 43, an inlet disc 44 and a connecting channel disc 45 shown in Fig. 3 are shown. Fig. 5 is a perspective view of a pilot body 16 seen from below. Fig. 6 illustrates the principle of a Helmholtz resonator. Fig. Figure 7 is a block diagram relating to vibration transmission from a pilot valve to a main valve. Fig. 8 shows an example of a transmission loss through the Helmholtz resonator and the relationship between the oscillation frequency of the pilot valve 19 and the target frequency of the opening and closing operation of the main valve 18. Fig. 9 is a bottom view showing a part of the component configuration constituting the control valve 113 according to a second embodiment of the present invention. Fig. 10 is a bottom view showing a part of the component configuration constituting the control valve 113 according to a third embodiment of the present invention. Fig. 11 is a schematic diagram illustrating another structural example 1 of a muffler according to a fourth embodiment of the present invention. Fig. 12 is a schematic diagram illustrating another structural example 2 of the muffler according to the fourth embodiment of the present invention. Fig. 13 is a schematic diagram illustrating another structural example 3 of the muffler according to the fourth embodiment of the present invention. Description of the Embodiments

[0009] An embodiment of the present invention will be described below with reference to the accompanying drawings. Note that the same elements are generally denoted by the same reference numerals throughout the drawings. Furthermore, explanations of parts having the same functions are omitted. It should be noted that the configurations described below are merely exemplary embodiments, and the embodiments of the present invention are not intended to be limited to the specific aspects below.

[0010] In this description, the upper direction on the attached drawings is defined as "upward" and the lower direction on the drawings is defined as "downward".

[0011] An example of the application of a valve according to the present invention to a shock absorber is described with reference to Fig. 1 described. Fig. 1 is a cross-sectional view illustrating the schematic configuration of a shock absorber 100 according to an embodiment of the present invention.

[0012] The shock absorber 100 is formed such that a rod 110 connected to a piston 111 protrudes from a part of a housing 115 forming the outer shell. The interior of the housing 115 is provided with an inner cylinder 106 that accommodates the piston 111 and an outer cylinder 107 arranged around the outer circumference of the inner cylinder 106. The housing 115 is arranged around the outer circumference of the outer cylinder 107. One end (top in the figure) of the outer cylinder 107 is open, and the other end (bottom in the figure) is closed by a closure part 107a. Both ends of the inner cylinder 106 are open, with one end (top in the figure) being closed in contact with the housing 115 and the other end (bottom in the figure) being closed in contact with the closure part 107a of the outer cylinder 107.

[0013] The interior of the inner cylinder 106 is divided by the piston 111 to form a lower piston chamber 101 located below the piston 111 and an upper piston chamber 102 located above the piston 111.

[0014] The piston 111 is formed with a piston flow channel 111a that allows communication between the lower piston chamber 101 and the upper piston chamber 102, and the piston flow channel 111a is equipped with a first check valve 112.

[0015] A connecting flow channel 104 containing hydraulic oil is formed between the inner cylinder 106 and the outer cylinder 107. A connecting opening 103 is formed in the inner cylinder 106, allowing communication between the upper piston chamber 102 and the connecting flow channel 104.

[0016] A reservoir chamber 105 is formed between the outer cylinder 107 and the housing 115. A closure flow channel 107b, which enables communication between the reservoir chamber 105 and the lower piston chamber 101, is formed in the closure part 107a of the outer cylinder 107, and the closure flow channel 107b is equipped with a second check valve 114.

[0017] The shock absorber 100 according to the present embodiment is further provided with a control valve 113 (valve) connected to the communication flow passage 104 and the reservoir chamber 105.

[0018] When an automobile drives over a step and the tires sink, the shock absorber 100 acts in a direction that retracts the rod 110 from the housing 115 (upward in the figure). This is called the extension stroke. During the extension stroke, the piston 111 connected to the rod 110 also moves upward in the figure, so that the hydraulic oil in the upper piston chamber 102 is pressurized. The hydraulic oil is therefore discharged through the connecting port 103 into the connecting flow channel 104 and is guided to the control valve 113.

[0019] The opening degree of the control valve 113 is adjusted according to a set value from a controller (not shown), thereby adjusting the pressure loss generated when the hydraulic oil flows through it, so that the damping force is adjusted as a shock absorber. The hydraulic oil flowing out of the control valve 113 is discharged into the reservoir chamber 105, passes through the second check valve 114, and is guided to the lower piston chamber 101. At this time, the volume increased in the lower piston chamber 101 is larger than the volume decreased in the upper piston chamber 102, but since gas is trapped in the reservoir chamber 105, the lack of movable hydraulic oil is compensated by the expansion of the gas.

[0020] For example, when an automobile drives over a step and the tires are lifted, the shock absorber 100 operates to push the rod 110 into the housing 115. This is called a retraction stroke. During the retraction stroke, the pressure of the hydraulic oil in the lower piston chamber 101 increases, so that the hydraulic oil in the lower piston chamber 101 flows through the first check valve 112 and flows into the upper piston chamber 102. At this time, the volume reduced in the lower piston chamber 101 is greater than the volume increased in the upper piston chamber 102, so the excess hydraulic oil is discharged through the communication port 103 into the communication flow passage 104 and guided to the control valve 113. As with the extension stroke described above, the hydraulic oil flowing through the control valve 113 is pressure-controlled and discharged into the reservoir chamber 105.At this time, since the pressure in the reservoir chamber 105 is lower than the pressure in the lower piston chamber 101, the hydraulic oil in the reservoir chamber 105 cannot flow through the second check valve 114, so that the increase of the hydraulic oil in the reservoir chamber 105 is absorbed by the compression of the gas present in the reservoir chamber 105.

[0021] A typical control valve 113' (comparative example) is described with reference to Fig. 2 described. Fig. Figure 2 is a cross-sectional view illustrating the schematic configuration of the typical control valve 113' (comparative example). The present invention is characterized by the control valve, and details will be described in the first to fourth embodiments described below.

[0022] The typical control valve 113' is integrated into a part of a hydraulic circuit for generating the damping force in the shock absorber 100. The shock absorber assumed here is such that hydraulic oil flows during extension and retraction. In the present embodiment, the shock absorber is such that the hydraulic oil flows in the same direction during both extension and retraction. Therefore, the control valve 113' is also intended for one in which the hydraulic oil flows internally in one direction. The illustrated control valve 113' is approximately cylindrical and has an axisymmetric shape except for some flow channels and structures. In the following explanation, a direction D1 along the center axis of the cylinder is referred to as the axial direction, and a direction D2 perpendicular to the axial direction D1 is referred to as the radial direction.

[0023] The mechanism by which the control valve 113' generates a damping force is shown below. Hydraulic oil flowing in from a control valve inlet 1 is split into two parts, one of which is supplied to a main pre-chamber 3 via a main inlet channel 2. The other flows through an inlet opening 15a formed as part of a pilot pin 15, is depressurized, and supplied to a pilot pre-chamber 4. The control valve inlet 1 and the main inlet channel 2 are connected to the connecting flow channel 104.

[0024] A pilot valve 19 includes a pilot valve seat 16a, which is part of a pilot body 16, and a pilot valve element 17. The opening and closing force of the pilot valve 19 is controlled by a solenoid or spring (not shown) mounted on top of the pilot valve element 17. The hydraulic oil flowing through the pilot valve 19 is directed through a pilot after-chamber 7 to a main after-chamber 8, which forms the outlet. The main after-chamber 8 is connected to the reservoir chamber 105.

[0025] When the pilot valve 19 is controlled in the closing direction, the pressure in the pilot pre-chamber 4 increases, and when the pilot valve 19 is controlled in the opening direction, the pressure in the pilot pre-chamber 4 decreases. Since the pilot pre-chamber 4 (pilot valve 19) is connected to a back pressure chamber 6 via a connecting channel 5, hydraulic oil is sucked in and discharged so that the pressures in the pilot pre-chamber 4 and the back pressure chamber 6 are the same.

[0026] The backpressure chamber 6 includes a main valve element 14 consisting of a rubber seal 13 and a metal disc 12, the pilot pin 15, and the pilot body 16. The backpressure chamber 6 is located on the back side of a main valve 18. The pilot valve 19 controls the pressure in the backpressure chamber 6 to open and close the main valve 18.

[0027] The main valve 18 includes the main valve element 14, the pilot pin 15, and a main body 11 that holds the main valve element 14, as well as a main valve seat 11a that is part of the main body 11. The main valve 18 controls the flow of hydraulic oil.

[0028] The disc 12 has an opening (through hole) 12b in its center through which the pilot pin 15 passes. The main valve element 14 is held by the main body 11 such that the inner peripheral part of the disc 12, in which the opening (through hole) 12b is formed, is sandwiched between the main body 11 and the pilot pin 15. In addition, in the comparative example of Fig. 2 the main valve seat 11a is formed integrally with the main body 11 and is thereby held by the main body 11.

[0029] Since the pressure-receiving area of ​​the main valve element 14 on the back pressure chamber 6 side is larger than the pressure-receiving area on the main pre-chamber 3 side, the main valve element 14 is pressed against the main pre-chamber 3 side when the opening degree of the pilot valve 19 is small. When the opening degree of the pilot valve 19 is large, the pressure in the pilot pre-chamber 4 drops, and therefore the pressure in the back pressure chamber 6 also drops. This reduces the pressing force of the main valve element 14, causing the main valve element 14 to move toward the back pressure chamber 6 side and open the main valve 18. When the main valve 18 is in the open state, the hydraulic oil flows from the main pre-chamber 3 through the main valve 18 into the main post-chamber 8.

[0030] Since the opening degree of the main valve 18 can be controlled by the opening degree of the pilot valve 19, the damping force of the shock absorber 100 equipped with the control valve 113' is controlled by controlling the flow resistance of the control valve 113'.

[0031] In the above-described control valve 113', when the main valve 18 operates in the opening direction, the volume of the back pressure chamber 6 decreases, so that the hydraulic oil in the back pressure chamber 6 is discharged into the pilot pre-chamber 4 through the connecting channel 5. Meanwhile, when the main valve 18 operates in the closing direction, the volume of the back pressure chamber 6 increases, so that the hydraulic oil is supplied from the pilot pre-chamber 4 to the back pressure chamber 6 through the connecting channel 5.

[0032] As described above, since smooth movement of the hydraulic oil through the connecting passage 5 is important for the opening and closing of the main valve 18, a wider flow passage cross-section of the connecting passage 5 is preferable. However, when the pilot valve 19 oscillates for some reason, the wider the flow passage cross-section of the connecting passage 5, the more likely the pressure change is to propagate to the back pressure chamber 6 via the connecting passage 5, and therefore the main valve 18 is more likely to oscillate. If the main valve 18 oscillates unexpectedly, this may result in the generation of abnormal noise or an abnormal damping force. Each embodiment of the present invention provides a structure that suppresses the propagation of this oscillation.

[0033] Embodiments of the control valve 113 to which the present invention is applied will be described below. First embodiment

[0034] The control valve 113 according to the first embodiment of the present invention will be described with reference to Fig. 3 and Fig. 4 described. Fig. 3 is a cross-sectional view illustrating the schematic configuration of the control valve 113 according to the first embodiment of the present invention. Fig. Fig. 4 is a bottom view of a branch channel disc 43, an inlet disc 44 and a connecting channel disc 45 shown in Fig. 3 are shown. Fig. Figure 5 is a perspective view of the pilot body 16 seen from below. Note that in Fig. 5, the pilot body 16 is shown upside down, with part of the configuration omitted. Configurations that are compatible with the Fig. 2 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0035] The control valve 113 according to the present embodiment differs from the control valve 113' in Fig. 2 in that it includes the branch channel disc 43, the inlet disc 44 and the connecting channel disc 45, and in that it includes a resonance chamber 42 (space) in the pilot body 16.

[0036] As in Fig. As shown in Figure 5, the resonance chamber 42 includes a recess (cavity) formed along the circumferential direction of the pilot body 16 and extending from the bottom to the top. The resonance chamber 42 also includes a bottom 42a and does not penetrate the pilot body 16 in the vertical direction.

[0037] The opening of the recess (cavity) on the backpressure chamber 6 side is closed by the branch channel disc 43. A through hole 41b with a smaller cross-sectional area than the opening is formed in the branch channel disc 43, and the opening of the recess (cavity) on the backpressure chamber 6 side is closed. In other words, the resonance chamber 42 (space) is formed by the recess (cavity) opening toward the backpressure chamber 6 and the branch channel disc 43, which closes the opening of the recess (cavity) and has the through hole 41b with a smaller cross-sectional area than the recess (cavity). The through hole 41b forms at least part of a branch channel 41.

[0038] The recess (cavity) has an axisymmetric structure around the D1 axis. The remaining configuration is similar to the control valve 113' in Fig. 2.

[0039] The open side (bottom side) of the resonance chamber 42 is covered with the branch channel disc 43, and the branch channel 41 formed in the branch channel disc 43 communicates with the resonance chamber 42. A cross-sectional area C1 of the resonance chamber 42 in a direction perpendicular to the vertical direction is larger than a cross-sectional area C2 of the branch channel 41 (through hole) in the region connected to the inlet of the resonance chamber 42 (C1 > C2). Furthermore, a volume V1 of the resonance chamber 42 is larger than a volume V2 of the branch channel 41 (V1 > V2).

[0040] The branch channel disc 43, the inlet disc 44, and the connecting channel disc 45 have openings (through holes) 43b, 44b, and 45b formed in their centers, respectively, through which the pilot pin 15 passes. The branch channel disc 43, the inlet disc 44, and the connecting channel disc 45 have inner peripheral portions held between the pilot body 16 and the pilot pin 15.

[0041] The branch passage disc 43 is formed with the branch passage 41 arranged to penetrate the branch passage disc 43 and extend radially. The branch passage 41 is formed in the vertical direction by being sandwiched between the inlet disc 44 and the pilot body 16.

[0042] The inlet disc 44 is formed with a branch inlet through-hole 41a that penetrates the inlet disc 44 and communicates with the branch channel 41 of the branch channel disc 43. The branch inlet through-hole 41a forms a part of the branch channel 41.

[0043] The connecting passage disc 45 is formed with the connecting passage 5, which penetrates the connecting passage disc 45, communicates with the opening (through hole) 45b, and extends radially outward from the opening (through hole) 45b. The branch passage 41 formed in the branch passage disc 43 communicates with the branch inlet through hole 41a on the radially inner side and with the resonance chamber 42 on the radially outer side.

[0044] When the branch passage disc 43, the inlet disc 44 and the connecting passage disc 45 are stacked, the connecting passage 5, the branch inlet through-hole 41a and the branch passage 41 communicate with each other, and the resonance chamber 42 and the connecting passage 5 are connected to each other through the branch inlet through-hole 41a and the branch passage 41.

[0045] In addition, the back pressure chamber 6 has the main valve element 14, the pilot pin 15, the pilot body 16 and the connecting channel disc 45.

[0046] A Helmholtz resonator is formed by inserting the resonance chamber 42 across the branch passage 41 with respect to the connecting passage 5, through which pressure oscillations can be transmitted by hydraulic oil. This makes it possible to suppress pressure oscillations of a specific frequency among the pressure oscillations propagating through the connecting passage 5. The resonance chamber 42 includes the branch passage 41 branching from the connecting passage 5 and a space connected to the branch passage 41 and extending to the opposite side of the connecting passage 5, with the branch passage 41 interposed therebetween. In the present embodiment, the branch passage 41 and the resonance chamber 42 form a resonance structure.

[0047] The Helmholtz resonator is briefly described here. Fig. 6 illustrates the principle of the Helmholtz resonator.

[0048] A neck 64 is connected to a body 63 of a bottle 62. If the speed of sound is v, the volume of the body 63 of the bottle 62 is V0 and the cross-sectional area and length of the neck 64 are S and L, respectively, the resonance frequency f H of the Helmholtz resonance as in equation (1) (Source: Simple Evidence for the Mechanism of Helmholtz Resonance and the Theory of Resonance Frequency, Yukkuri Machine Learning (laid-back-scientist.com)). [Mathematical Formula 1] ƒH=υ2πSV0L

[0049] Considering the mathematical formula 1, the frequency to be suppressed can be calculated from the cross-sectional area and length of the branch channel, the volume of the resonance chamber and the speed of sound of the hydraulic oil filling the space, so it is sufficient to determine the shape of each according to the pressure propagation frequency to be suppressed.

[0050] Furthermore, the response frequency to be achieved by opening and closing the main valve 18 with the pilot valve 19 is approximately one order of magnitude lower than the oscillation frequency of the pilot valve 19 whose transmission is to be suppressed. Since the Helmholtz resonator can concentrate the suppression near the frequency to be suppressed, the transmission attenuation at that frequency can be sufficiently reduced when the frequency to be transmitted is almost one order of magnitude away. As a result, the deterioration of the response characteristic of the pilot valve 19 due to the installation of the Helmholtz resonator becomes negligible.

[0051] Fig. Figure 7 is a block diagram relating to vibration transmission from the pilot valve to the main valve. Structurally, a Helmholtz resonator 60 includes the branch channel 41 branching from the connecting channel 5 and the resonance chamber 42, but the transmission of vibrations is represented by a state in which the pilot valve 19 and the main valve 18 are connected in series with the Helmholtz resonator 60 in between.

[0052] In the Helmholtz resonator 60, the transmission attenuation TL at the frequency f can be calculated by the following equation (2), where l b represents the length of the branch channel 41, a represents the radius of the branch channel 41, V represents the volume of the resonance chamber 42 and S represents the flow channel cross-sectional area of ​​the connecting channel 5. [Mathematical Formula 2] TL=10⋅log(1+14(C0VSƒƒr−ƒrƒ)2)

[0053] Here f rand C0 are calculated by the following equations (3) and (4), respectively, where C is the speed of sound. [Mathematical Formula 3] ƒr=C2πC0V [Mathematical Formula 4] C0=2πa22lb+πa

[0054] (Source: On the Reduction of Engine Noise (Part 2), by Itsuo Ohnaka, Journal of the Japan Institute of Marine Engineering, Volume 4, No. 4, p. 179 (1969))

[0055] Fig. 8 shows an example of the transmission loss by the Helmholtz resonator and the relationship between the oscillation frequency of the pilot valve 19 and the target frequency of the opening and closing operation of the main valve 18. In the Helmholtz resonator 60, it can be confirmed that almost no loss occurs at the opening and closing frequency of the main valve 18, while a large loss occurs at the oscillation frequency of the pilot valve 19.

[0056] In the conventional structure, it is necessary to give priority to either reducing the flow channel cross-sectional area of ​​the connecting channel 5 to suppress pressure propagation or increasing the flow channel cross-sectional area of ​​the connecting channel 5 to improve the response speed of opening and closing of the main valve 18.

[0057] With the structure according to the present embodiment, a structure forming a Helmholtz resonator is provided inside the control valve 113, so that the flow channel cross-sectional area of ​​the connecting channel 5 can be increased, thereby improving the response speed of opening and closing of the main valve 18 and also suppressing pressure oscillations propagating through the connecting channel 5. Second embodiment

[0058] The control valve 113 according to a second embodiment of the present invention will be described with reference to Fig. 9 described. Fig. 9 is a bottom view showing a part of the component configuration constituting the control valve 113 according to the second embodiment of the present invention.

[0059] The control valve 113 according to the present embodiment differs from the control valve 113 in Fig. 3 in that it includes an inlet disc 46, a branch channel disc 47, and an outlet disc 48, which form the branch channel 41 of the Helmholtz resonator. The remaining configuration is similar to the control valve 113 in Fig. 3. In the present embodiment, the branch passage 41 is formed by stacking the plurality of disks (the inlet disk 46, the branch passage disk 47, and the outlet disk 48).

[0060] The branch channel of the Helmholtz resonator according to the present embodiment is formed by stacking, from bottom to top, the connecting channel disc 45, the inlet disc 46, the branch channel disc 47, and the outlet disc 48. These discs are formed in a substantially circular shape.

[0061] The connecting channel disc 45, the inlet disc 46, the branch channel disc 47, and the outlet disc 48 have openings (through holes) 45b, 46b, 47b, and 48b, respectively, in their centers, through which the pilot pin 15 passes. The connecting channel disc 45, the inlet disc 46, the branch channel disc 47, and the outlet disc 48 have inner peripheral portions held between the pilot body 16 and the pilot pin 15.

[0062] The connecting channel disc 45 is formed with the connecting channel 5, which penetrates the connecting channel disc 45, communicates with the opening (through hole) 45b and extends radially outward from the opening (through hole) 45b.

[0063] The inlet disc 46 is formed with the branch inlet through-hole 41a, which penetrates the inlet disc 46 and communicates with the branch channel 41 of the branch channel disc 47. The branch inlet through-hole 41a forms a part of the branch channel 41.

[0064] The branch channel disc 47 has a spiral-shaped cutout portion 41n that penetrates the branch channel disc 47 and extends in the circumferential direction of the branch channel disc 47. The branch channel 41 is then formed by closing the cutout portion 41n from above and below with the inlet disc 46 and the outlet disc 48. In other words, the inlet disc 46 and the outlet disc 48 serve as the flow channel wall surface of the branch channel 41.

[0065] The outlet disc 48 is formed with a branch outlet through-hole 41c that penetrates the outlet disc 48 and communicates with the branch channel 41. The branch outlet through-hole 41c forms a part of the branch channel 41.

[0066] When the connecting channel disc 45, the inlet disc 46, the branch channel disc 47 and the outlet disc 48 are stacked, the connecting channel 5, the branch inlet through-hole 41a, the branch channel 41 and the branch outlet through-hole 41c communicate with each other, and the resonance chamber 42 and the connecting channel 5 are connected via the branch inlet through-hole 41a, the branch channel 41 and the branch outlet through-hole 41c.

[0067] The present embodiment is characterized in that the spiral branch channel 41 is formed on the branch channel disc 47. The spiral branch channel 41 according to the present embodiment has a longer flow channel length than the branch channel 41 formed on the branch channel disc 43 according to the first embodiment. The frequency at which propagation by the Helmholtz resonator is suppressed can be adjusted by the length of the branch flow channel. According to the present embodiment, the effective length of the branch channel 41 can be changed by changing the installation angle of the combination of the connecting channel disc 45 and the inlet disc 46, so that propagation suppression corresponding to the oscillation frequency generated by the pilot valve 19 can be easily achieved.

[0068] In addition, by extending the branch inlet through-hole 41a in the inlet disk 46 in the outer peripheral direction, it is also possible to connect to the second and subsequent rows from the inner peripheral side of the branch channel 41 in the branch channel disk 47, and by selectively using this structure in combination, the range of frequencies that can be processed can be further expanded.

[0069] Furthermore, in the present embodiment, the outlet disk 48 is installed to connect the resonance chamber 42 to the branch passage 41 on the outer peripheral side, thereby extending the branch passage 41 in the branch passage disk 47 to the outer peripheral side and enabling an increase in the flow passage length. However, the outlet disk 48 is not required as long as the desired propagation suppression frequency can be achieved when the branch passage 41 in the branch passage disk 47 is connected to the inner peripheral side of the resonance chamber 42. Therefore, the outlet disk 48 is not an essential configuration under these conditions.

[0070] In order to achieve equivalent propagation suppression frequencies while simultaneously increasing the flow channel cross-sectional area of ​​the branch channel 41, it is necessary to lengthen the branch channel 41. Since the larger the flow channel cross-sectional area, the easier it is to manufacture (machine), it is preferable that the length of the branch channel 41 in the branch channel disk 47 is long.

[0071] In the present embodiment, the cutout part 41n formed in the branch passage disk 47 is formed in a spiral shape, but the cutout part 41n may be formed in a curved shape, for example. Third embodiment

[0072] The control valve 113 according to a third embodiment of the present invention will be described with reference to Fig. 10 described. Fig. 10 is a bottom view showing a part of the component configuration constituting the control valve 113 according to the third embodiment of the present invention.

[0073] The control valve 113 according to the present embodiment differs from the control valve 113 according to the second embodiment in that a connecting channel disc 45', an inlet disc 46', a branch channel disc 47', and an outlet disc 48', which form the branch channel 41 of the Helmholtz resonator, each have a key groove 52, and the pilot body 16 in which these discs are installed includes a key 51. The remaining configuration is similar to the control valve 113 according to the second embodiment.

[0074] The branch channel of the Helmholtz resonator according to the present embodiment is formed by stacking, from bottom to top, the connecting channel disc 45', the inlet disc 46', the branch channel disc 47', and the outlet disc 48' with their respective key grooves 52 aligned and then inserting them in alignment with the key 51 of the pilot body 16.

[0075] According to the present embodiment, it is possible to accurately align the disks forming the branch channel, and it is possible to suppress the loss of the positional relationship between the disks during or after assembly, thereby achieving and maintaining maximum transmission damping of pressure vibrations at a precise frequency. Furthermore, four key grooves 52 are formed on the outer circumference of each of the plurality of disks in Fig. 9 are provided, but this number is not essential and can be reduced if necessary. It is sufficient that at least one keyway 52 is provided. Alternatively, more keyways can be installed to further improve adjustment accuracy.

[0076] In the present invention, the material of each disc in contact with the branch passage 41 is preferably metal, but one or two of the constituent discs may be made of a resin-based material such as rubber. If the flatness of the discs is poor, there is a possibility that hydraulic oil will flow between the stacked discs. Therefore, by replacing some of the discs with resin discs, the adhesion between the discs can be improved and accidental hydraulic oil leakage can be suppressed.

[0077] Furthermore, the depth of the counterbore in the pilot body 16 into which each disc in contact with the branch passage 41 is inserted may be shallower on the outer peripheral side than on the inner peripheral side. In this case, each disc held between the pilot body 16 and the pilot pin 15 is lifted on the outer peripheral side while being pressed against the pilot body 16 on the inner peripheral side, so that a spring force is generated due to the deformation of each disc, thereby improving the adhesion between the discs and suppressing hydraulic oil leakage.

[0078] Furthermore, in the present invention, the structure of the resonance chamber is a single axially symmetric space, but this space can be provided with walls to form multiple spaces of different volumes. In this case, the target frequency at which transmission loss is generated can be easily changed by selecting the space to which the branch duct is to be connected. Fourth embodiment

[0079] Other structural examples of silencers are described with reference to the Fig. 11 to 13 described. Fig. 11 is a schematic diagram illustrating another structural example 1 of a muffler according to a fourth embodiment of the present invention. Fig. 12 is a schematic diagram illustrating another structural example 2 of the muffler according to the fourth embodiment of the present invention. Fig. 13 is a schematic diagram illustrating another structural example 3 of the muffler according to the fourth embodiment of the present invention. [Further structural example 1]

[0080] As in Fig. As shown in FIG. 11, a muffler 70 according to Structural Example 1 is constituted by two extension parts 71 and 72 connected by a connecting pipe 73. An inlet pipe 74 communicating with the pilot valve 19 is connected to the extension part 71. In addition, an outlet pipe 75 communicating with the back pressure chamber 6 is connected to the extension part 72.

[0081] The fluid (hydraulic oil) flowing through the inlet pipe 74 flows into the extension part 71, which has a larger cross-sectional area than the inlet pipe 74. The fluid (hydraulic oil) flowing into the extension part 71 reduces its velocity and pressure, which are factors contributing to noise. The fluid (hydraulic oil) with reduced velocity and pressure flows through the connecting pipe 73 in an amount corresponding to its cross-sectional area, and the remaining fluid (hydraulic oil) is reflected by the inner wall of the extension part 71, further reducing the velocity and pressure that cause noise.

[0082] The fluid (hydraulic oil) flowing through the connecting pipe 73 flows into the extension part 72, which has a larger cross-sectional area than the connecting pipe 73. The fluid (hydraulic oil) flowing into the extension part 72 reduces its velocity and pressure, which are factors contributing to noise. The fluid (hydraulic oil) with reduced velocity and pressure is discharged from the outlet pipe 75 in an amount corresponding to the cross-sectional area of ​​the outlet pipe 75, and the remaining fluid (hydraulic oil) is reflected by the inner wall of the extension part 72, further reducing the velocity and pressure that cause noise. In this way, the muffler 70 reduces noise generation. [Further structural example 2]

[0083] As in Fig. As shown in Fig. 12, in a muffler 80 according to Structural Example 2, an inlet pipe 82 communicating with the pilot valve 19 and an outlet pipe 83 communicating with the back pressure chamber 6 are connected to an extension part 81. Further, the inlet pipe 82 extends into the interior of the extension part 81 and includes a passage part 82a. Similarly, the outlet pipe 83 extends into the interior of the extension part 81 and includes a passage part 83a.

[0084] The fluid (hydraulic oil) flowing through the inlet pipe 82 and the passage portion 82a flows into the extension portion 81, which has a larger cross-sectional area than the passage portion 82a. The fluid (hydraulic oil) flowing into the extension portion 81 reduces its velocity and pressure, which are factors contributing to noise. The fluid (hydraulic oil) with reduced velocity and pressure flows through the passage portion 83a of the outlet pipe 83 in an amount corresponding to its cross-sectional area, and the remaining fluid (hydraulic oil) is reflected by the inner wall of the extension portion 81, further reducing the velocity and pressure that cause noise. In this way, the muffler 80 reduces noise generation. [Further structural example 3]

[0085] As in Fig.As shown in Fig. 13, in a muffler 90 according to the third structural example, an inlet pipe 92 communicating with the pilot valve 19 and an outlet pipe 93 communicating with the back pressure chamber 6 are connected to an extension part 91. Further, the interior of the extension part 91 is divided into a first extension part 91a and a second extension part 91b by a partition wall 94. A part of the partition wall 94 is cut out, and this cut out part is provided with a channel part 95 that enables communication between the first extension part 91a and the second extension part 91b.

[0086] The fluid (hydraulic oil) flowing through the inlet pipe 92 flows into the first extension part 91a, which has a larger cross-sectional area than the inlet pipe 92. The fluid (hydraulic oil) flowing into the first extension part 91a reduces its velocity and pressure, which are factors contributing to noise. The fluid (hydraulic oil) with reduced velocity and pressure flows through the channel part 95 in an amount corresponding to its cross-sectional area, and the remaining fluid (hydraulic oil) is reflected by the inner wall of the extension part 81 and the partition wall 94, thereby further reducing the velocity and pressure that cause noise.

[0087] The fluid (hydraulic oil) flowing through the passage part 95 flows into the second extension part 91b, which has a larger cross-sectional area than the passage part 95. The fluid (hydraulic oil) flowing into the second extension part 91b reduces its velocity and pressure, which are factors contributing to noise. The fluid (hydraulic oil) with reduced velocity and pressure is discharged from the outlet pipe 93 in an amount corresponding to the cross-sectional area of ​​the outlet pipe 93, and the remaining fluid (hydraulic oil) is reflected by the inner wall of the second extension part 91b and the partition wall 94, thereby further reducing the velocity and pressure that cause noise. In this way, the muffler 90 reduces noise generation.

[0088] It should be noted that the present invention is not limited to the above-described embodiments and includes various modification examples. For example, the above-described embodiments have been described in detail to facilitate understanding of the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Moreover, part of the configuration of one embodiment may be replaced with the configurations of other embodiments, and in addition, the configuration of one embodiment may also be supplemented with the configurations of other embodiments. Furthermore, part of the configuration of each of the embodiments may be added, deleted, and replaced with other configurations. List of reference symbols

[0089] 1: Control valve inlet, 2: Main inlet port, 3: Main pre-flow chamber, 4: Pilot pre-chamber, 5: Connecting port, 6: Back pressure chamber, 7: Post-chamber, 8: Main post-chamber, 11: Main body, 11a: Main valve seat, 12: Disc, 12b: Orifice (through hole), 13: Rubber seal, 14: Main valve element, 15: Pilot pin, 15a: Inlet port, 16: Pilot body, 16a: Pilot valve seat, 17: Pilot valve element, 18: Main valve, 19: Pilot valve, 41: Branch port, 41a: Branch inlet through hole, 41b: Through hole, 41c: Branch outlet through hole, 41n: Cut-out part, 42: Resonance chamber, 42a: Bottom, 43: Branch duct disc, 43b: Opening (through hole), 44: Inlet disc, 44b: Opening (through hole), 45: Connecting duct disc, 45': Connecting duct disc, 45b: Opening (through hole), 46: Inlet disc, 46': Inlet disc, 46b: Opening (through hole), 47: Branch duct disc, 47': Branch duct disc, 47b: Opening (through hole), 48: Outlet disc, 48': Outlet disc,48b: Opening (through hole), 51: Key, 52: Keyway, 60: Helmholtz resonator, 62: Bottle, 63: Body, 64: Neck, 70: Silencer, 71: Extension part, 72: Extension part, 73: Connecting pipe, 74: Inlet pipe, 75: Outlet pipe 80: Silencer, 81: Extension part, 82: Inlet pipe, 82a: Channel part, 83: Outlet pipe, 83a: Channel part, 90: Silencer, 91: Extension part, 91a: First extension part, 91b: Second extension part, 92: Inlet pipe, 93: Outlet pipe, 94: Partition, 95: Channel part, 100: Shock absorber, 101: Lower piston chamber, 102: Upper piston chamber, 103: connecting port, 104: connecting flow channel, 105: reservoir chamber, 106: inner cylinder, 107: outer cylinder, 107a: closure part, 107b: closure part flow channel, 110: rod, 111: piston, 111a: piston flow channel, 112: first check valve, 113: control valve, 113': control valve, 114: second check valve, 115: housing, QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2016-7918

[0003] Cited non-patent literature

[0000] On the Reduction of Engine Noise (Part 2), by Itsuo OHNAKA, Journal of the Japan Institute of Marine Engineering, Volume 4, No. 4, p. 179 (1969

[0054]

Claims

[1] A shock absorber equipped with a control valve that controls a damping force by adjusting a pressure of hydraulic oil flowing through the control valve, the control valve comprising: a main valve for controlling a flow of the hydraulic oil; a pilot valve for opening and closing the main valve by controlling a pressure in a back pressure chamber disposed at a rear side of the main valve; a communication passage allowing communication between the pilot valve and the back pressure chamber; and a resonance structure that suppresses pressure oscillations transmitted by the hydraulic oil in the communication passage. [2] The shock absorber according to claim 1, wherein the resonance structure includes: a branch passage branching from the connecting passage; and a space connected to the branch passage and extending to a side opposite to the connecting passage, the branch passage being arranged between the space and the connecting passage. [3] The shock absorber according to claim 1, wherein the resonance structure is a Helmholtz resonator including: a branch channel branching from the connecting channel; and a space connected to the branch channel and having a volume larger than a volume of the branch channel. [4] Shock absorber according to claim 2, wherein the space is formed by a cavity opening towards the backpressure chamber and an element closing the opening of the cavity and having a through hole with a smaller cross-sectional area than the opening, and the through hole of the element forms at least part of the branch channel. [5] A shock absorber according to claim 4, wherein the branch passage is formed by closing a curved cut-out part in a substantially round disc with another substantially round disc to serve as a flow passage wall surface. [6] The shock absorber according to claim 4, wherein the branch passage is formed by closing a spiral cut-out portion penetrating one substantially circular disc with another substantially circular disc to serve as a flow passage wall surface. [7] A shock absorber according to claim 4, wherein the branch channel is formed by stacking a plurality of substantially circular discs, each of the discs having at least one key groove for alignment. [8] Shock absorber according to claim 4, wherein in materials a plurality of discs forming the branch channel include at least one metal disc and at least one plastic disc. [9] A shock absorber according to claim 1, further comprising: an inner cylinder accommodating a piston connected to a rod; an outer cylinder disposed around an outer periphery of the inner cylinder; a housing disposed around an outer periphery of the outer cylinder; a connecting flow channel formed between the inner cylinder and the outer cylinder; and a reservoir chamber formed between the outer cylinder and the housing, wherein the control valve is arranged to connect the connecting flow channel to the reservoir chamber. [10] A valve comprising: a main valve for controlling a flow of hydraulic oil; a pilot valve for opening and closing the main valve by controlling a pressure in a back pressure chamber disposed on a back side of the main valve; and a communication passage allowing communication between the pilot valve and the back pressure chamber, the valve further comprising a resonance structure that suppresses pressure oscillations transmitted by the hydraulic oil in the communication passage.

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