Pressure damping device

A pressure damping device includes a cylinder, a partitioning section, a flow channel formation section, a valve section a bypass channel and a throttle section. The flow channel formation section forms a flow channel, through which the fluid flows, in conjunction with a movement of the partitioning section. The valve section controls a flow of the fluid in the flow channel of the flow channel formation section. The bypass channel forms a flow of the fluid that bypasses the flow of the fluid flowing through the flow channel while opening the valve section. The throttle section that throttles the flow of the fluid through the bypass channel further on an outer side than the valve section with respect to the flow channel formation section.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2015-165806, filed Aug. 25, 2015. The contents of this application are incorporated herein by reference in their entirety.

BACKGROUND

Field

The present invention relates to a pressure damping device.

Related Art

A suspension device of a vehicle such as an automobile is provided with a pressure damping device which dampens vibration transmitted from a road surface to the vehicle during traveling. In addition, among pressure damping devices of this type, a pressure damping device that enables a generated damping force to be varied is known (for example, refer to JP H0613392 (Y2)).

SUMMARY

In a pressure damping device that enables a damping force to be varied, favorably, machining of the pressure damping device can be easily performed.

An object of the present disclosure is to enable a pressure damping device, which is capable of varying a damping force, to be easily machined.

To achieve the object described above, the present disclosure provides a pressure damping device including: a cylinder that extends from one side toward another side and that houses a fluid; a partitioning section that is provided so as to be movable in an axial direction in the cylinder and that partitions a space in the cylinder into a first chamber and a second chamber; a flow channel formation section in which a flow channel, through which the fluid flows, is formed in conjunction with a movement of the partitioning section; a valve section that controls a flow of the fluid in the flow channel of the flow channel formation section; a bypass channel that forms a flow of the fluid that bypasses the flow of the fluid flowing through the flow channel while opening the valve section; and a throttle section that throttles the flow of the fluid through the bypass channel further on an outer side than the valve section with respect to the flow channel formation section.

By adopting the configuration described above, since a structure is realized in which a throttle section throttles a flow of a fluid in a bypass channel further on an outer side than a valve section with respect to a flow channel formation section, a pressure damping device capable of varying a damping force can be easily machined.

According to the present disclosure, a pressure damping device capable of varying a damping force can be easily machined.

DESCRIPTION OF THE EMBODIMENTS

First Embodiment

FIG. 1is an overall configuration diagram of a hydraulic damping device1according to a first embodiment.

In the following description, a lower side inFIG. 1in an axial direction of the hydraulic damping device1shown inFIG. 1will be referred to as “one side” and an upper side inFIG. 1will be referred to as “another side”. In addition, a center of the hydraulic damping device1in a radial direction will be referred to as an “inner side in the radial direction” and an outer side in the radial direction will be referred to as an “outer side in the radial direction”.

[Configuration and Functions of Hydraulic Damping Device1]

As shown inFIG. 1, the hydraulic damping device1(a pressure damping device according to the present invention) includes a cylinder section10, a rod section20which is provided so that the other side thereof protrudes outside of the cylinder section10and the one side thereof is slidably inserted into the cylinder section10, a piston constituting section30which is provided at a one side-end of the rod section20, and a bottom valve section70which is provided at a one side-end of the cylinder section10.

In addition, although not illustrated, the hydraulic damping device1is provided between a vehicle body and an axle in a four-wheel automobile, a motorcycle, and the like to dampen vibrational movement of the rod section20with respect to the cylinder section10.

Next, a general configuration of the hydraulic damping device1according to the first embodiment will be described.

As shown inFIG. 1, the hydraulic damping device1includes: a cylinder11which extends from one side toward another side and which houses oil (a fluid); a housing31(a partitioning section) which is provided so as to be movable in an axial direction in the cylinder11and which partitions a space in the cylinder11into a first oil chamber Y1(a first chamber) and a second oil chamber Y2(a second chamber); a valve seat41(a flow channel formation section) in which a compression side oil channel416(a flow channel) through which the oil flows is formed in conjunction with a movement of the housing31; a compression side second valve43(a valve section) which controls a flow of the oil in the compression side oil channel416of the valve seat41; a bypass oil channel471(a bypass channel) which forms a flow of the oil that bypasses the flow of the oil flowing through the compression side oil channel416while opening the compression side second valve43; and a throttle section60V which throttles the flow of the oil through the bypass oil channel471further on the outer side (more specifically, the other side in the axial direction) than the compression side second valve43with respect to the valve seat41. Hereinafter, these components will be described in detail.

The cylinder section10includes the cylinder11, an outer cylindrical body12which is provided on the outer side of the cylinder11, and a bottom section13which is provided at a one side-end of the outer cylindrical body12. In addition, in the present embodiment, a reservoir chamber R which stores oil is formed between the cylinder11and the outer cylindrical body12.

Furthermore, the cylinder section10includes a rod guide14which is provided at another side-end of the cylinder11and a seal member15which closes another side-end of the outer cylindrical body12.

In the present embodiment, the rod section20includes a rod member21which is formed to as to extend in an axial direction, a one side-mounting section21awhich is provided at a one side-end of the rod member21, and another side-mounting section21bwhich is provided at another side-end of the rod member21.

The one side-mounting section21aof the rod member21holds the piston constituting section30. In addition, a coupling member (not shown) for coupling the hydraulic damping device1to a vehicle body of an automobile or the like is mounted to the other side-mounting section21bof the rod member21.

The piston constituting section30includes the housing31, a piston section40which is provided on an inner side of the housing31in the radial direction, and a damping force changing section60which is provided on the other side of the piston section40.

Moreover, the respective components of the piston constituting section30will be described in detail later.

In addition, in the present embodiment, the piston constituting section30divides a space in the cylinder11into a first oil chamber Y1and a second oil chamber Y2which house oil. In the present embodiment, the first oil chamber Y1is formed on the one side of the piston constituting section30(a piston ring314to be described later) and the second oil chamber Y2is formed on the other side of the piston constituting section30.

The bottom valve section70is provided on a one side-end of the hydraulic damping device1and divides the first oil chamber Y1and the reservoir chamber R from each other.

[Configuration and Function of Piston Constituting Section30]

FIG. 2is a sectional view of the piston constituting section30according to the first embodiment.

FIG. 3is a conceptual diagram of the damping force changing section60according to the first embodiment.

As shown inFIG. 2, the housing31is a hollow member which opens on the one side. In addition, the housing31includes a rod connecting section311which is provided on the other side, a holding section312which is provided on the one side, an opening313which is provided on the one side of the rod connecting section311, and the piston ring314which is provided on an outer circumference of the housing31. Furthermore, an outer diameter of the housing31is smaller than an inner diameter of the cylinder11. Moreover, the housing31forms a housing inner chamber31Y on the inner side in the radial direction which is also the other side of the piston section40.

The rod connecting section311is a screw hole which is formed so as to extend in the axial direction. The one side-mounting section21aof the rod member21is fixed to the rod connecting section311. In addition, the rod connecting section311is provided with a seal member (not shown) which provides a seal between the rod connecting section311and the one side-mounting section21a.

The holding section312holds a fixing member312L that fixes the piston section40and the damping force changing section60which are housed in the housing31.

The opening313is an opening approximately facing the radial direction. In addition, the opening313is provided in plurality in the circumferential direction of the housing31. Furthermore, the plurality of openings313are arranged at equal intervals in the circumferential direction.

The piston ring314is provided so as to be in slidable contact with an inner circumferential surface of the cylinder11. The piston ring314reduces frictional resistance between the housing31and the cylinder11.

The piston section40includes the valve seat41, a compression side first valve42which is provided on the other side of the valve seat41, a compression side second valve43which is provided on the other side of the compression side first valve42, an extension side first valve44which is provided on the one side of the valve seat41, an extension side second valve45which is provided on the one side of the extension side first valve44, a seal member46which is provided between the valve seat41and the housing31, a bolt47, a nut48, and a compression side inter-valve member49which is provided between the compression side first valve42and the compression side second valve43. In addition, a compression side inter-valve chamber42Y into which oil flows is formed between the compression side first valve42and the compression side second valve43.

The valve seat41is an approximately columnar member which includes an opening41H through which the bolt47is passed. In addition, the valve seat41includes a compression side first annular section411which is provided on the other side, a compression side second annular section412which is provided on the other side, a compression side third annular section413which is provided on the other side, an extension side first annular section414which is provided on the one side, an extension side second annular section415which is provided on the one side, a compression side oil channel416, an extension side first oil channel417, and an extension side second oil channel418.

The compression side first annular section411is formed in an approximate ring shape on the outer side in the radial direction of the opening41H. In addition, the compression side first annular section411protrudes toward the other side in the axial direction.

The compression side second annular section412is formed in an approximate ring shape on the outer side in the radial direction of the compression side first annular section411. In addition, the compression side second annular section412protrudes toward the other side in the axial direction. Moreover, in the first embodiment, a protrusion height of the compression side second annular section412is formed at an approximately same height as the compression side first annular section411.

The compression side third annular section413is formed in an approximate ring shape on the outer side in the radial direction of the compression side second annular section412. In addition, the compression side third annular section413protrudes toward the other side in the axial direction. A protrusion height of the compression side third annular section413is higher than the compression side second annular section412. In other words, another side-end of the compression side third annular section413is positioned further on the other side than the compression side second annular section412.

The extension side first annular section414is formed in an approximate ring shape on the outer side in the radial direction of the opening41H. In addition, the extension side first annular section414protrudes toward the one side in the axial direction.

The extension side second annular section415is formed in an approximate ring shape on the outer side in the radial direction of the extension side first annular section414. In addition, the extension side second annular section415protrudes toward the one side in the axial direction. A protrusion height of the extension side second annular section415is higher than the extension side first annular section414. In other words, a one side-end of the extension side second annular section415is positioned further on the one side than the extension side first annular section414.

The compression side oil channel416has a one side-oil port positioned on the outer side of the extension side second annular section415in the radial direction and another side-oil port positioned between the compression side first annular section411and the compression side second annular section412.

The extension side first oil channel417has a one side-oil port positioned on the inner side of the extension side first annular section414in the radial direction and another side-oil port positioned on the outer side of the compression side third annular section413in the radial direction.

The extension side second oil channel418has a one side-oil port positioned between the extension side first annular section414and the extension side second annular section415and another side-oil port positioned on the inner side of the extension side first annular section414in the radial direction. In addition, in the first embodiment, the extension side second oil channel418connects to the bypass oil channel471(a bypass channel) inside the valve seat41separately from the compression side oil channel416and the extension side first oil channel417(a flow channel).

The compression side first valve42is constituted by a disc-shaped metal plate material. In addition, the compression side first valve42is configured so as to be capable of coming into contact with the compression side first annular section411and the compression side second annular section412. Furthermore, the compression side first valve42opens the compression side oil channel416when oil flows through the compression side oil channel416toward the second oil chamber Y2. Moreover, the compression side first valve42always opens the other side of the extension side second oil channel418.

The compression side second valve43is constituted by a disc-shaped metal plate material. In addition, the compression side second valve43is configured so as to be capable of coming into contact with the compression side third annular section413. Furthermore, the compression side second valve43is configured so as to be less deformable than the compression side first valve42. In the first embodiment, the compression side second valve43is configured so as not to open at least under oil pressure that applies when the compression side first valve42starts to open. Moreover, the compression side second valve43(an outer side-valve) extends further to the outer side in the radial direction than the compression side first valve42(an inner side-valve) with respect to the valve seat41and operates so as to close when oil flows though the bypass oil channel471(a bypass channel) as will be described later.

The extension side first valve44is constituted by a disc-shaped metal plate material. In addition, the extension side first valve44is configured so as to be capable of coming into contact with the extension side first annular section414. Furthermore, the extension side first valve44opens the extension side first oil channel417when oil flows through the extension side first oil channel417toward the first oil chamber Y1. Moreover, the extension side first valve44is configured so as to be less deformable than the extension side second valve45. In the first embodiment, the extension side first valve44is configured so as not to open at least under oil pressure that applies when the extension side second valve45starts to open.

The extension side second valve45is constituted by a disc-shaped metal plate material. In addition, the extension side second valve45is configured so as to be capable of coming into contact with the extension side second annular section415. Furthermore, the extension side second valve45opens the extension side first oil channel417when oil flows through the extension side first oil channel417toward the first oil chamber Y1. Moreover, the extension side second valve45opens the extension side second oil channel418when oil flows through the extension side second oil channel418toward the first oil chamber Y1.

Moreover, settings of oil pressure that applies when the extension side first valve44and the extension side second valve45open are not limited to the settings described in the embodiment above and other settings may be adopted.

In the first embodiment, the bolt47is fixed to a one side-end of the rod member21. In addition, together with the nut48, the bolt47sandwiches and holds the valve seat41, the compression side first valve42, the compression side second valve43, the extension side first valve44, the extension side second valve45, and the compression side inter-valve member49.

Furthermore, the bolt47includes the bypass oil channel471, an opposing section472formed on the other side, and a connecting section473formed on the other side and further on the outer side in the radial direction than the opposing section472.

The bypass oil channel471is formed in the axial direction on the other side of the bolt47. In addition, the bypass oil channel471penetrates the bolt47in the radial direction in a part of the bolt47but does not penetrate the bolt47in the axial direction. More specifically, the bypass oil channel471communicates with an adjustment chamber60Y (to be described later) on the other side and communicates with an opening491(to be described later) on the one side.

The opposing section472is formed at a position that opposes a protruding section642of the damping force changing section60.

The connecting section473comes into contact with a second cam housing63(to be described later) of the damping force changing section60. In addition, the connecting section473forms a connection location with the damping force changing section60. Furthermore, the connecting section473includes a plurality of openings473R.

The compression side inter-valve member49includes an opening491that penetrates the compression side inter-valve member49in the radial direction. In addition, an inner side in the radial direction of the opening491communicates with the bypass oil channel471. Meanwhile, an outer side in the radial direction of the opening491faces the compression side inter-valve chamber42Y.

As shown inFIG. 2, the damping force changing section60includes a solenoid61, a first cam housing62which is provided on the other side, the second cam housing63which is provided on the one side, a shutter valve64which is provided between the first cam housing62and the second cam housing63, and a spring65which is provided on the other side of the shutter valve64.

The solenoid61is controlled by a control unit (not shown) via a conductive wire (not shown). In addition, the solenoid61generates a magnetic field when energized. In the first embodiment, the solenoid61moves the shutter valve64to the other side with a generated magnetic field.

The first cam housing62includes a flange section621formed on the other side and a cylindrical section622formed on the one side.

The flange section621is fixed to the housing31by being press-fitted into an inner circumference of the housing31and pressed against the housing31toward the other side by the solenoid61.

As shown inFIG. 3, the cylindrical section622includes a plurality of first inclined surface sections622L. The plurality of first inclined surface sections622L are continuously formed in the circumferential direction of the first cam housing62.

As shown inFIG. 3, the second cam housing63includes a plurality of first depressed sections631, a plurality of second depressed sections632, a plurality of third depressed sections633, and a plurality of second inclined surface sections634. In addition, in the first embodiment, the first depressed section631, the second inclined surface section634, the second depressed section632, the first depressed section631, the second inclined surface section634, the third depressed section633, and the first depressed section631are respectively cyclically arranged in this order in the circumferential direction of the second cam housing63.

Furthermore, the first depressed section631is configured such that a distance from a prescribed reference (for example, a one side-end of the first cam housing62) on the other side is a distance L1which is longer than distances to the second depressed section632and the third depressed section633. The second depressed section632is configured such that a distance from the reference is a distance L2which is shorter than a distance to the first depressed section631. The third depressed section633is configured such that a distance from the reference is a distance L3which is shorter than a distance to the second depressed section632. In this manner, the first depressed section631, the second depressed section632, and the third depressed section633are respectively configured such that depths thereof from the reference on the other side in one direction become sequentially shallower.

Moreover, an order of arrangement of the first depressed section631, the second depressed section632, and the third depressed section633in the circumferential direction is not limited to the order described above and other configurations may be adopted instead.

As shown inFIG. 2, the shutter valve64includes a guided section641which is provided on the outer side in the radial direction and a protruding section642which is provided on the one side. In addition, the protruding section642forms the throttle section60V which throttles a flow of oil between the protruding section642and the opposing section472of the bolt47. Furthermore, the shutter valve64forms the adjustment chamber60Y which is a space into which oil flows between the shutter valve64and the bolt47. Moreover, in the first embodiment, the throttle section60V is provided on an outer side-end of the piston section40.

As shown inFIG. 3, the guided section641includes a first guided section6411formed on the other side and a second guided section6412formed on the one side.

The first guided section6411includes an inclined surface. In addition, the inclined surface of the first guided section6411is formed so as to conform to the first inclined surface section622L of the first cam housing62. The first guided section6411is a portion to be guided by the first cam housing62in a state where the shutter valve64is pressed against the first guided section6411toward the other side.

The second guided section6412includes an inclined surface. In addition, the inclined surface of the second guided section6412is formed so as to conform to the second inclined surface section634, the second depressed section632, and the third depressed section633of the second cam housing63. Furthermore, the second guided section6412is a portion to be guided by the second cam housing63in a state where the shutter valve64is pressed against the second guided section6412toward the one side.

As shown inFIG. 2, with the spring65, the one side thereof is in contact with the shutter valve64and the other side thereof is in contact with the first cam housing62. In addition, the spring65imparts, to the shutter valve64, a force that causes the shutter valve64to move toward the one side.

In the damping force changing section60configured as described above, the shutter valve64(a protruding member) rotates by being driven in the axial direction by the solenoid61(a driving section) and, at the same time, protrudes toward the bypass oil channel471(a bypass channel) by a prescribed protrusion amount in accordance with an amount of rotation. In addition, the shutter valve64changes an interval between the protruding section642and the opposing section472(a throttle amount of oil) in accordance with a protrusion amount (a position) of the shutter valve64in the axial direction. Accordingly, the shutter valve64throttles a flow of oil that flows through the bypass oil channel471as will be described later.

As described above, in the first embodiment, depths toward the one side increases in an order of the third depressed section633, the second depressed section632, and the first depressed section631(refer toFIG. 3). Therefore, in a state where the guided section641is fitted into the first depressed section631(depicted by a dashed-dotted line inFIG. 3), the protrusion amount of the protruding section642toward the one side assumes a maximum value. In addition, the damping force changing section60forms a “closed state” where the protruding section642and the opposing section472come into contact with each other and closes the bypass oil channel471. Furthermore, in a state where the guided section641is fitted into the second depressed section632(depicted by a solid line inFIG. 3), the damping force changing section60forms a “first opened state” where oil flows more readily through the bypass oil channel471than in the closed state. Moreover, in a state where the guided section641is fitted into the third depressed section633(depicted by a dashed-two dotted line inFIG. 3), the damping force changing section60forms a “second opened state” where oil flows more readily through the bypass oil channel471than in the first opened state.

<Operations of Damping Force Changing Section60>

FIGS. 4A to 4Care explanatory diagrams of operations of the damping force changing section60.

Hereinafter, operations when the shutter valve64rotates due to energization of the solenoid61(refer toFIG. 2) in the damping force changing section60will be described.

With reference to the example shown inFIG. 4A, operations from a state where the second guided section6412of the guided section641is fitted into the second depressed section632will be described. Moreover, as described above, this state constitutes a first opened state.

In addition, in the damping force changing section60, the solenoid61moves the shutter valve64to the other side. As a result, as shown inFIG. 4B, the first guided section6411of the guided section641comes into contact with the first inclined surface section622L of the first cam housing62. In addition, the first guided section6411slides on the first inclined surface section622L. As a result, the shutter valve64rotates in the circumferential direction as a whole.

Subsequently, the damping force changing section60suspends energization of the solenoid61. As a result, the shutter valve64is pressed toward the one side by the spring65(refer toFIG. 2). At this point, in the example shown inFIG. 4C, the second guided section6412comes into contact with the second inclined surface section634. In addition, the second guided section6412slides on the second inclined surface section634and the shutter valve64rotates in the circumferential direction as a whole.

Furthermore, eventually, a state where the guided section641is fitted into the first depressed section631is created. As described earlier, this state constitutes a closed state.

In a similar manner, by performing energization and suspension thereof of the solenoid61once, the shutter valve64rotates by an amount of rotation (angle) determined in advance. In addition, the guided section641of the shutter valve64moves to other adjacent depressed sections (the first depressed section631, the second depressed section632, and the third depressed section633) in accordance with the amount of rotation.

The solenoid61is energized only when the shutter valve64is rotated. In other words, once the shutter valve64is positioned at a predetermined rotational position, the solenoid61need not be energized. The rotational position of the shutter valve64is maintained by the second cam housing63which meshes with the shutter valve64and by the spring65. Therefore, with the hydraulic damping device1according to the first embodiment, a state of the shutter valve64is maintained even in a state where power is not supplied as compared to electric drive sources such as the solenoid61.

Operations of Hydraulic Damping Device1According to First Embodiment

FIGS. 5A and 5Bare explanatory diagrams of operations of the hydraulic damping device1according to the first embodiment.

Moreover, inFIGS. 5A and 5B, a flow of oil during a compression stroke will be depicted by a solid line and a flow of oil during an extension stroke will be depicted by a dashed line. In addition,FIG. 5Ais a diagram showing a case where the closed state is formed in the damping force changing section60.FIG. 5Bis a diagram showing a case where the first opened state is formed in the damping force changing section60.

First, a flow of oil when the closed state is formed in the damping force changing section60will be described. In addition, hereinafter, descriptions applicable during a compression stroke and during an extension stroke will be respectively given in this order.

When the piston constituting section30moves to the one side in the axial direction with respect to the cylinder11, as indicated by a solid line arrow inFIG. 5A, oil in the first oil chamber Y1flows through the compression side oil channel416and flows out to the compression side inter-valve chamber42Y while pressing and opening the compression side first valve42. Furthermore, the oil having flowed out to the compression side inter-valve chamber42Y passes through the housing inner chamber31Y and the opening313and flows out to the second oil chamber Y2while pressing and opening the compression side second valve43.

As described above, during a compression stroke in the closed state, a damping force is mainly generated by resistance created when oil flows through the compression side oil channel416, the compression side first valve42, and the compression side second valve43.

In addition, as shown inFIG. 1, in the bottom valve section70, the oil in the first oil chamber Y1flows out to the reservoir chamber R due to a movement of the piston constituting section30to the one side in the axial direction.

As indicated by a dashed line arrow inFIG. 5A, when the piston constituting section30moves to the other side in the axial direction with respect to the cylinder11, oil in the second oil chamber Y2flows through the opening313, the housing inner chamber31Y, and the extension side first oil channel417and flows out to the extension side inter-valve chamber44Y while pressing and opening the extension side first valve44. Furthermore, the oil having flowed out to the extension side inter-valve chamber44Y flows out to the first oil chamber Y1while pressing and opening the extension side second valve45.

As described above, during an extension stroke in the closed state, a damping force is mainly generated by resistance created when oil flows through the extension side first oil channel417, the extension side first valve44, and the extension side second valve45.

In addition, as shown inFIG. 1, in the bottom valve section70, the oil in the reservoir chamber R flows into the first oil chamber Y1due to a movement of the piston constituting section30to the other side in the axial direction.

Next, a flow of oil when the first opened state is formed in the damping force changing section60will be described.

As shown inFIG. 5B, in the first opened state, a state exists where the protruding section642of the shutter valve64has separated from the opposing section472of the bolt47and the throttle section60V has opened. In other words, in the hydraulic damping device1, a flow of oil via the bypass oil channel471is enabled.

When the piston constituting section30moves to the one side in the axial direction with respect to the cylinder11, as indicated by a solid line arrow inFIG. 5B, oil in the first oil chamber Y1flows into the compression side oil channel416and flows out to the compression side inter-valve chamber42Y while pressing and opening the compression side first valve42. Subsequently, the oil in the compression side inter-valve chamber42Y flows through the opening491, the bypass oil channel471, the adjustment chamber60Y, the throttle section60V, the opening473R, the housing inner chamber31Y, and the opening313and flows out to the second oil chamber Y2. In this manner, in the first opened state, oil flows so as to bypass the flow of oil which presses and opens the compression side second valve43.

As described above, during a compression stroke in the first opened state, a damping force is mainly generated by resistance created when oil flows through the compression side oil channel416and the compression side first valve42. In addition, the damping force generated in the first opened state is smaller than the damping force generated in the closed state.

As indicated by a dashed line arrow inFIG. 5B, when the piston constituting section30moves to the other side in the axial direction with respect to the cylinder11, oil in the second oil chamber Y2flows through the opening313, the housing inner chamber31Y, the opening473R, the throttle section60V, the adjustment chamber60Y, and the bypass oil channel471in this order. In addition, the oil in the bypass oil channel471flows into the extension side second oil channel418and flows out to the first oil chamber Y1while pressing and opening the extension side second valve45. In this manner, in the first opened state, oil flows so as to bypass the flow of oil which presses and opens the extension side first valve44.

As described above, during an extension stroke in the first opened state, a damping force is mainly generated by resistance created when oil flows through the extension side second oil channel418and the extension side second valve45. In addition, the damping force generated in the first opened state is smaller than the damping force generated in the closed state.

Furthermore, as described above, the bypass oil channel471forms both a flow that bypasses the compression side second valve43during a compression stroke and a flow that bypasses the extension side first valve44during an extension stroke. Accordingly, a device configuration of the hydraulic damping device1is simplified.

(During Compression Stroke and During Extension Stroke/Second Opened State)

Next, a flow of oil when the second opened state (a state where the guided section641is fitted into the third depressed section633) is formed in the damping force changing section60will be described.

In this case, a flow of oil in the second opened state is similar to that in the first opened state (a state where the guided section641is fitted into the second depressed section632). However, in the second opened state, a throttle amount of the throttle section60V in the damping force changing section60is smaller as compared to the first opened state. Therefore, the damping force generated in the second opened state is smaller than the damping forces generated in the closed state and the first opened state.

As described above, with the hydraulic damping device1according to the first embodiment, by adjusting a flow of oil in the bypass oil channel471using the damping force changing section60, a magnitude of a generated damping force can be changed. In addition, in the first embodiment, the throttle section60V which throttles the flow of oil in the bypass oil channel471is formed further on the outer side than the valves (the compression side first valve42, the compression side second valve43, the extension side first valve44, and the extension side second valve45) with respect to the valve seat41. Accordingly, for example, compared to a case where the throttle section60V is formed on the inner side of the valves with respect to the valve seat41, machining when manufacturing the hydraulic damping device1can be easily performed.

In addition, in the first embodiment, flows of oil through the bypass oil channel471are switched using the damping force changing section60that operates under electric control. Furthermore, by switching the flows of oil through the bypass oil channel471, for example, one of or both the compression side first valve42and the compression side second valve43are opened by the flow of oil. In this manner, in the first embodiment, instead of directly operating the compression side first valve42and the compression side second valve43by electric control, the compression side first valve42and the compression side second valve43are indirectly controlled by switching flows of oil in the bypass oil channel471by electric control.

Moreover, while the oil throttle amounts adjusted at the throttle section60V of the damping force changing section60are set to three stages, namely, the closed state, the first opened state, and the second opened state in the first embodiment, a plurality of stages may be further provided for the opened state.

In other words, the oil throttle amounts to be adjusted at the throttle section60V may be set to the two stages of the closed state and the first opened state. In addition, the oil throttle amounts to be adjusted at the throttle section60V may be set to stages of a third opened state and more in addition to the first opened state and the second opened state according to the embodiment described above.

Furthermore, in the first embodiment, the piston section40(the valve seat41, the compression side first valve42, the compression side second valve43, the extension side first valve44, and the extension side second valve45) is provided inside the housing31. Therefore, in the piston constituting section30, the piston section40can be readily replaced with a piston section of another type. On the other hand, the housing31and the damping force changing section60can be commonly used in the piston constituting section30.

First Modification

Next, the hydraulic damping device1according to a first modification will be described.

FIG. 6is an explanatory diagram of the valve seat41to which the first modification is applied.

In the hydraulic damping device1according to the first modification, a structure of the valve seat41differs from that of the valve seat41according to the first embodiment. Specifically, as shown inFIG. 6, the valve seat41according to the first modification has a split structure which includes a first structure section41A and a second structure section41B.

The first structure section41A is a portion which is provided on the other side inFIG. 6and the second structure section41B is a portion which is provided on the one side inFIG. 6. In addition, in the first modification, the first structure section41A and the second structure section41B are joined together to integrally constitute the valve seat41.

In the first structure section41A, other side-parts of the compression side oil channel416and the extension side first oil channel417are formed. The compression side oil channel416is formed in a groove shape. In addition, the compression side oil channel416is configured to constitute an oil channel when the first structure section41A and the second structure section41B are joined together. Furthermore, the extension side first oil channel417is formed as a through-hole.

In the second structure section41B, one side-parts of the extension side second oil channel418and the extension side first oil channel417are formed. The extension side first oil channel417and the extension side second oil channel418of the second structure section41B are formed as through-holes. In addition, the extension side first oil channel417of the second structure section41B is configured to constitute a single oil channel by connecting to the extension side first oil channel417of the first structure section41A when the first structure section41A and the second structure section41B are joined together.

Moreover, although not illustrated, the first structure section41A and the second structure section41B respectively include positioning sections in the circumferential direction such as protrusions and depressions. The positioning sections determine a relative positional relationship between the first structure section41A and the second structure section41B in the circumferential direction.

With the valve seat41according to the first modification configured as described above, for example, the compression side oil channel416can be formed by a protrusion strip section having been formed in a mold. Therefore, for example, the time required by machining such as cutting can be reduced and, as a result, the hydraulic damping device1can be machined more easily. In addition, for example, due to the split configuration of the first structure section41A and the second structure section41B, the hydraulic damping device1can be machined more easily as exemplified by an increased degree of freedom of penetration angles of tools when cutting the extension side first oil channel417and the extension side second oil channel418as through-holes.

Moreover, the valve seat41is not limited to the two-way split described above and a configuration may be adopted in which the valve seat41is split three ways or more.

Second Modification

Next, the hydraulic damping device1according to a second modification will be described.

FIG. 7is an explanatory diagram of the piston constituting section30according to the second modification.

As shown inFIG. 7, the piston constituting section30according to the second modification includes the piston section40and the damping force changing section60which is provided between the piston section40and the rod member21. In other words, the piston constituting section30according to the second modification does not include the housing31.

Even with a structure not provided with the housing31as in the case of the second modification, by arranging the throttle section60V further on the outer side (the other side in the axial direction) than the valves (the compression side first valve42, the compression side second valve43, the extension side first valve44, and the extension side second valve45) with respect to the valve seat41, the hydraulic damping device1can be machined more easily.

Second Embodiment

FIG. 8is a sectional view of a piston constituting section300according to a second embodiment.

Moreover, in the second embodiment, members similar to those of the first embodiment will be assigned same numbers and detailed descriptions thereof will be omitted.

[Configuration and Function of Piston Constituting Section300]

The piston constituting section300includes a housing31, a piston section240which is provided on an inner side of the housing31in the radial direction, and a damping force changing section60which is provided on the other side of the piston section240.

Next, a general configuration of the hydraulic damping device1according to the second embodiment will be described.

As shown inFIG. 8, the hydraulic damping device1includes: a cylinder11which extends from one side toward another side and which houses oil (a fluid); a housing31(a partitioning section) which is provided so as to be movable in an axial direction in the cylinder11and which partitions a space in the cylinder11into a first oil chamber Y1(a first chamber) and a second oil chamber Y2(a second chamber); a valve seat241(a flow channel formation section) in which a compression side oil channel416(a flow channel) through which the oil flows is formed in conjunction with a movement of the housing31; a compression side second valve43(a valve section) which controls a flow of the oil in the compression side oil channel416of the valve seat241; a bypass oil channel2471(a bypass channel) which forms a flow of the oil that bypasses the flow of the oil flowing through the compression side oil channel416while opening the compression side second valve43; and a throttle section60V which throttles the flow of the oil through the bypass oil channel2471further on the outer side (more specifically, the other side in the axial direction) than the compression side second valve43with respect to the valve seat241. Hereinafter, these components will be described in detail.

In the piston constituting section300according to the second embodiment, a configuration of the piston section240differs from that of the piston section40according to the first embodiment. Hereinafter, the piston section240will be described in detail.

A basic configuration of the piston section240according to the second embodiment is similar to that of the piston section40according to the first embodiment. However, the piston section240mainly differs from the first embodiment in configurations of a bolt247, a valve seat241, an extension side first valve242, an extension side inter-valve member249, and an extension side second valve243.

The valve seat241includes the compression side oil channel416and an extension side first oil channel417but does not include the extension side second oil channel418according to the first embodiment.

Basic configurations of the extension side first valve242and the extension side second valve243are respectively approximately similar to those of the compression side first valve42and the compression side second valve43with the exception of being provided on the one side of the valve seat241. In addition, in the second embodiment, an extension side inter-valve chamber242Y into which oil flows is formed between the extension side first valve242and the extension side second valve243.

The extension side inter-valve member249includes an extension side opening2491that penetrates the extension side inter-valve member249in the radial direction.

The bolt247includes a bypass oil channel2471. The bypass oil channel2471penetrates the bolt247in the radial direction in a part of the bolt247but does not penetrate the bolt247in the axial direction. In addition, the bypass oil channel2471communicates with the extension side opening2491of the extension side inter-valve member249on the one side in the axial direction and communicates with the opening491of the compression side inter-valve member49on the other side.

Operations of Hydraulic Damping Device1According to Second Embodiment

FIGS. 9A and 9Bare explanatory diagrams of operations of the hydraulic damping device1according to the second embodiment.

Moreover, inFIGS. 9A and 9B, a flow of oil during a compression stroke will be depicted by a solid line and a flow of oil during an extension stroke will be depicted by a dashed line. In addition,FIG. 9Ais a diagram showing a case where a closed state is formed in the damping force changing section60.FIG. 9Bis a diagram showing a case where a first opened state is formed in the damping force changing section60.

First, a flow of oil when the closed state is formed in the damping force changing section60will be described. In addition, hereinafter, descriptions applicable during a compression stroke and during an extension stroke will be respectively given in this order.

As indicated by a solid line arrow inFIG. 9A, a flow of oil in the piston constituting section300during a compression stroke is similar to the flow of oil in the piston constituting section30according to the first embodiment.

As indicated by a dashed line arrow inFIG. 9A, when the piston constituting section30moves to the other side in the axial direction with respect to the cylinder11, oil in the second oil chamber Y2flows through the opening313, the housing inner chamber31Y, and the extension side first oil channel417and flows out to the extension side inter-valve chamber242Y while pressing and opening the extension side first valve242. Furthermore, the oil having flowed out to the extension side inter-valve chamber242Y flows out to the first oil chamber Y1while pressing and opening the extension side second valve243.

As described above, during an extension stroke in the closed state, a damping force is mainly generated by resistance created when oil flows through the extension side first oil channel417, the extension side first valve242, and the extension side second valve243.

Next, a flow of oil when the first opened state is formed in the damping force changing section60will be described.

As shown inFIG. 9B, in the first opened state, a state exists where the protruding section642of the shutter valve64has separated from the opposing section472and the throttle section60V has opened. In other words, in the hydraulic damping device1, a flow of oil via the bypass oil channel2471is enabled.

As indicated by a solid line arrow inFIG. 9B, a flow of oil in the piston constituting section300in the first opened state during a compression stroke is similar to the flow of oil in the piston constituting section30according to the first embodiment.

As indicated by a dashed line arrow inFIG. 9B, when the piston constituting section300moves to the other side in the axial direction with respect to the cylinder11, oil in the second oil chamber Y2flows through the opening313, the housing inner chamber31Y, the opening473R, the throttle section60V, the adjustment chamber60Y, and the bypass oil channel2471in this order. In addition, the oil in the bypass oil channel2471flows into the extension side opening2491and flows out to the first oil chamber Y1while pressing and opening the extension side second valve243. In this manner, in the first opened state, oil flows so as to bypass the flow of oil which presses and opens the extension side first valve242.

As described above, during an extension stroke in the first opened state, a damping force is mainly generated by resistance created when oil flows through the extension side second valve243. In addition, the damping force generated in the first opened state is smaller than the damping force generated in the closed state.

(During Compression Stroke and During Extension Stroke/Second Opened State)

Next, a flow of oil when the second opened state is formed in the damping force changing section60will be described.

In this case, a flow of oil in the second opened state is approximately similar to that in the first opened state. However, in the second opened state, a throttle amount of the throttle section60V in the damping force changing section60is smaller as compared to the first opened state. Therefore, the damping force generated in the second opened state is smaller than the damping forces generated in the closed state and the first opened state.

As described above, with the hydraulic damping device1according to the second embodiment, by adjusting a flow of oil in the bypass oil channel2471using the damping force changing section60, a magnitude of a generated damping force can be changed. In addition, in the second embodiment, the throttle section60V which throttles the flow of oil in the bypass oil channel2471is formed further on the outer side than the valves (the compression side first valve42, the compression side second valve43, the extension side first valve242, and the extension side second valve243) with respect to the valve seat241. Accordingly, for example, compared to a case where the throttle section60V is formed on the inner side of the valves with respect to the valve seat241, machining when manufacturing the hydraulic damping device1can be readily performed.

Third Embodiment

FIG. 10is a sectional view of a piston constituting section230according to a third embodiment.

Moreover, in the third embodiment, members similar to those of the first embodiment will be assigned same numbers and detailed descriptions thereof will be omitted.

[Configuration and Function of Piston Constituting Section230]

The piston constituting section230includes a housing31, a first piston section80which is provided on the inner side of the housing31in the radial direction, a second piston section50which is provided on the inner side of the housing31in the radial direction which is also the one side of the first piston section80, and a damping force changing section60which is provided on the inner side of the housing31which is also the other side of the first piston section80.

Moreover, in the third embodiment, an intermediate oil chamber M1into which oil flows is formed between the first piston section80and the second piston section50.

Next, a general configuration of the hydraulic damping device1according to the third embodiment will be described.

As shown inFIG. 10, the hydraulic damping device1includes: a cylinder11which extends from one side toward another side and which houses oil (a fluid); a housing31(a partitioning section) which is provided so as to be movable in an axial direction in the cylinder11and which partitions a space in the cylinder11into a first oil chamber Y1(a first chamber) and a second oil chamber Y2(a second chamber); a first valve seat80S (a flow channel formation section) in which a flow channel through which the oil flows is formed in conjunction with a movement of the housing31; a damping valve83(a valve section) which controls a flow of the oil in the oil channel of the first valve seat80S; a bypass oil channel811(a bypass channel) which forms a flow of the oil that bypasses the flow of the oil flowing through the oil channel while opening the damping valve83; and a throttle section60V which throttles the flow of the oil through the bypass oil channel811further on the outer side than the damping valve83with respect to the first valve seat80S. Hereinafter, these components will be described in detail.

As shown inFIG. 10, the first piston section80includes the first valve seat80S. In addition, the first valve seat80S includes an extension side valve seat81which is provided on the other side and a compression side valve seat82which is provided on the one side of the extension side valve seat81. Furthermore, the first piston section80includes the damping valve83which is provided between the extension side valve seat81and the compression side valve seat82, a first seal member84which is provided on an outer circumference of the compression side valve seat82, and a bolt85.

The extension side valve seat81is an approximately columnar member which includes an opening81H through which the bolt85is passed. In addition, the extension side valve seat81includes a plurality of the bypass oil channels811which are formed so as to extend in the axial direction, an opposing section812formed on the other side, a connecting section813formed on the other side and further on the outer side in the radial direction than the opposing section812, and an extension side contacting section814formed on the inner side in the radial direction.

The bypass oil channels811form a pathway of oil that bypasses a flow of oil which flows as the damping valve83deforms in a direction of separation from the extension side contacting section814or a compression side contacting section822(to be described later) of the compression side valve seat82.

The opposing section812is formed at a position that opposes a protruding section642of the damping force changing section60. In addition, in the third embodiment, the opposing section812forms the throttle section60V between the protruding section642and the opposing section812.

The connecting section813comes into contact with a second cam housing63. In addition, the connecting section813forms a connection location with the damping force changing section60. Furthermore, the connecting section813includes a plurality of openings813R.

The extension side contacting section814is a ring-shaped surface which is formed by steps and which faces the one side. In addition, the extension side contacting section814forms a portion which is on the inner side of the damping valve83in the radial direction and with which the other side of the damping valve83comes into contact.

The compression side valve seat82is an approximately disc-shaped member which includes an opening82H through which the bolt85is passed. In addition, the compression side valve seat82includes an opening821formed on the outer side of the opening82H in the radial direction and the compression side contacting section822which is formed further on the outer side in the radial direction than the opening821.

The opening821is formed so as to penetrate in the axial direction. In the third embodiment, the opening821is provided in plurality in the circumferential direction of the compression side valve seat82.

The compression side contacting section822annularly protrudes toward the other side. In addition, the compression side contacting section822forms a portion which is on the outer side of the damping valve83in the radial direction and with which the one side of the damping valve83comes into contact.

Furthermore, in the first valve seat80S according to the third embodiment, a flow channel through which oil flows in conjunction with a movement of the piston constituting section230in the axial direction is formed between the extension side contacting section814and the compression side contacting section822.

The damping valve83is constituted by a disc-shaped metal plate material which includes an opening83H through which the extension side contacting section814is passed. In addition, by deforming, the damping valve83forms a state where oil flows while the damping valve83is separated from the extension side contacting section814of the extension side valve seat81and a state where oil flows while the damping valve83is separated from the compression side contacting section822of the compression side valve seat82. In other words, the damping valve83is configured to control a flow (a first flow) of oil in conjunction with a movement of the piston constituting section230toward the one side during a compression stroke and a flow (a second flow) of oil in conjunction with a movement of the piston constituting section230toward the other side during an extension stroke by a single member (a single body). Furthermore, in the third embodiment, the damping valve83is arranged on a side where the throttle section60V of the first valve seat80S is provided.

The first seal member84provides a seal between the compression side valve seat82and the housing31.

The bolt85is connected to a female screw formed on an inner circumference of the opening81H of the extension side valve seat81. In addition, the bolt85holds various parts of the first piston section80and the second piston section50which are sandwiched between the extension side valve seat81and a one side-end of the bolt85.

As shown inFIG. 10, the second piston section50includes a second valve seat51, a second compression side damping valve52which is provided on the other side of the second valve seat51, a second extension side damping valve53which is provided on a one side-end of the second valve seat51, and a second seal member54which is provided on the outer side in the radial direction of the second valve seat51.

The second valve seat51includes a plurality of second compression side oil channels511formed in an approximately axial direction on the outer side in the radial direction and a plurality of second extension side oil channels512formed in an approximately axial direction on the outer side in the radial direction.

The second compression side damping valve52is constituted by a disc-shaped metal plate material. In addition, the second compression side damping valve52makes the other side of the second compression side oil channels511of the second valve seat51to be openable and closable and always opens the other side of the second extension side oil channels512of the second valve seat51.

The second extension side damping valve53is constituted by a disc-shaped metal plate material. In addition, the second extension side damping valve53makes the one side of the second extension side oil channels512of the second valve seat51to be openable and closable and always opens the one side of the second compression side oil channels511of the second valve seat51.

Operations of Hydraulic Damping Device1According to Third Embodiment

FIGS. 11A and 11Bare explanatory diagrams of operations of the hydraulic damping device1according to the third embodiment.

Moreover, inFIGS. 11A and 11B, a flow of oil during a compression stroke will be depicted by a solid line and a flow of oil during an extension stroke will be depicted by a dashed line. In addition,FIG. 11Ais a diagram showing a case where a closed state is formed in the damping force changing section60.FIG. 11Bis a diagram showing a case where a first opened state is formed in the damping force changing section60.

First, a flow of oil when the closed state is formed in the damping force changing section60will be described. In addition, hereinafter, descriptions applicable during a compression stroke and during an extension stroke will be respectively given in this order.

When the piston constituting section230moves to the one side in the axial direction with respect to the cylinder11, as indicated by a solid line arrow inFIG. 11A, oil in the first oil chamber Y1flows into the second compression side oil channels511and flows out to the intermediate oil chamber M1while pressing and opening the second compression side damping valve52. Furthermore, the oil having flowed out to the intermediate oil chamber M1passes through the opening821and, while pressing and opening the compression side valve seat82at the compression side contacting section822, flows through the housing inner chamber31Y and the opening313and flows out to the second oil chamber Y2.

As described above, during a compression stroke in the closed state, a damping force is mainly generated by resistance created when oil flows through the second compression side oil channels511and between the second compression side damping valve52and the compression side valve seat82.

Moreover, in the closed state, the throttle section60V is in a closed state in the damping force changing section60. Therefore, in the closed state, a flow of oil via the bypass oil channel811such as that described later is not formed.

When the piston constituting section230moves to the other side in the axial direction with respect to the cylinder11, as indicated by a dashed line arrow inFIG. 11A, oil in the second oil chamber Y2flows through the opening313and the housing inner chamber31Y and flows out to the intermediate oil chamber M1through the opening821while pressing and opening the damping valve83at the extension side contacting section814. In addition, the oil having flowed out to the intermediate oil chamber M1flows into the second extension side oil channels512. Furthermore, the oil having flowed into the second extension side oil channels512flows out to the first oil chamber Y1while opening the second extension side damping valve53.

As described above, during an extension stroke in the closed state, a damping force is mainly generated by resistance created when oil flows through the damping valve83, the second extension side oil channels512, and the second extension side damping valve53.

As described above, when a closed state is formed in the damping force changing section60, damping forces are generated in both the first piston section80and the second piston section50.

Next, a flow of oil when the first opened state is formed in the damping force changing section60will be described.

As shown inFIG. 11B, in the first opened state, a state exists where the throttle section60V has opened. Therefore, in the first opened state, oil flows so as to bypass the pathway through which oil flows while pressing and opening the damping valve83. Moreover, in this case, the flow of oil in the second piston section50is the same as in the case of the closed state described above. Therefore, a flow of oil in the first piston section80in the first opened state will be mainly described below.

As indicated by a solid line arrow inFIG. 11B, when the piston constituting section230moves to the one side in the axial direction with respect to the cylinder11, a flow of oil in the second piston section50is created. In addition, the oil flows out from the first oil chamber Y1to the intermediate oil chamber M1. Furthermore, the oil having flowed out to the intermediate oil chamber M1flows through the opening821and the bypass oil channel811to the adjustment chamber60Y. Moreover, the oil having flowed to the adjustment chamber60Y passes through the throttle section60V, the opening813R, the housing inner chamber31Y, and the opening313and flows out to the second oil chamber Y2.

As described above, during a compression stroke in the first opened state, a damping force is mainly generated by resistance created when oil flows through the second compression side oil channels511and the second compression side damping valve52in the second piston section50described above. In addition, a certain damping force is also generated in the damping force changing section60when oil flows through the throttle section60V.

As indicated by a dashed line arrow inFIG. 11B, when the piston constituting section230moves to the other side in the axial direction with respect to the cylinder11, oil in the second oil chamber Y2flows through the opening313, the housing inner chamber31Y, the opening813R, and the throttle section60V and flows into the adjustment chamber60Y. In addition, the oil in the adjustment chamber60Y flows through the bypass oil channel811and the opening821and flows out to the intermediate oil chamber M1.

Furthermore, the oil in the intermediate oil chamber M1causes a flow of oil in the second piston section50. Moreover, eventually, the oil in the intermediate oil chamber M1flows out to the first oil chamber Y1.

As described above, during an extension stroke in the first opened state, a damping force is mainly generated by resistance created when oil flows through the second extension side oil channels512and the second extension side damping valve53in the second piston section50described above. In addition, a certain damping force is also generated in the damping force changing section60when oil flows through the throttle section60V.

In the closed state described above, oil serially flows through both the first piston section80and the second piston section50. In contrast, in the first opened state, oil mainly flows through the second piston section50. Therefore, the damping force generated in the first opened state is smaller than the damping force generated in the closed state.

In addition, as described above, the bypass oil channel811forms both a flow that bypasses the damping valve83during a compression stroke and a flow that bypasses the damping valve83during an extension stroke. Accordingly, with the third embodiment, a device configuration of the hydraulic damping device1is simplified.

Moreover, a flow of oil in the second opened state is approximately similar to that in the first opened state described above. However, the damping force in the second opened state is smaller than the damping forces generated in the closed state and the first opened state.

As described above, even with the hydraulic damping device1according to the third embodiment, a magnitude of a generated damping force can be changed using the damping force changing section60. In addition, in the third embodiment, the throttle section60V is similarly formed further on the outer side than the valve (the damping valve83) with respect to the first valve seat80S. Accordingly, machining when manufacturing the hydraulic damping device1is simplified.

Fourth Embodiment

FIG. 12is a sectional view of a piston constituting section330according to a fourth embodiment.

Moreover, in the fourth embodiment, members similar to those of the other embodiments will be assigned same numbers and detailed descriptions thereof will be omitted.

[Configuration and Function of piston Constituting Section330]

As shown inFIG. 12, the piston constituting section330according to the fourth embodiment includes a housing31, a third piston section90which is provided on an inner side of the housing31in the radial direction, and a damping force changing section160which is provided on the other side of the third piston section90.

Next, a general configuration of the hydraulic damping device1according to the fourth embodiment will be described.

As shown inFIG. 12, the hydraulic damping device1includes: a cylinder11which extends from one side toward another side and which houses oil (a fluid); a housing31(a partitioning section) which is provided so as to be movable in an axial direction in the cylinder11and which partitions a space in the cylinder11into a first oil chamber Y1(a first chamber) and a second oil chamber Y2(a second chamber); a third valve seat91(a flow channel formation section) in which an extension side first oil channel915(a flow channel) through which the oil flows is formed in conjunction with a movement of the housing31; an extension side first valve93(a valve section) which controls a flow of the oil in the extension side first oil channel915of the third valve seat91; a bypass oil channel951(a bypass channel) which forms a flow of oil that bypasses the flow of the oil flowing through the extension side first oil channel915while opening the extension side first valve93; and a throttle section160V which throttles the flow of the oil through the bypass oil channel951further on the outer side than the extension side first valve93with respect to the third valve seat91. Hereinafter, these components will be described in detail.

The third piston section90includes the third valve seat91, a compression side valve92which is provided on the other side of the third valve seat91, the extension side first valve93which is provided on the one side of the third valve seat91, an extension side second valve94which is provided on the one side of the extension side first valve93, a bolt95, and a nut96.

In addition, in the fourth embodiment, an inter-valve chamber93Y into which oil flows is formed between the extension side first valve93and the extension side second valve94.

The third valve seat91is an approximately columnar member which includes an opening91H through which the bolt95is passed. In addition, the third valve seat91includes a compression side annular section911which is provided on the other side, an extension side first annular section912which is provided on the one side, an extension side second annular section913which is provided on the one side of the extension side first annular section912, a compression side oil channel914, an extension side first oil channel915, and an extension side second oil channel916.

The compression side annular section911is formed in an approximate ring shape on the outer side in the radial direction of the opening91H. In addition, the compression side annular section911protrudes toward the other side in the axial direction.

The extension side first annular section912is formed in an approximate ring shape on the outer side in the radial direction of the opening91H. In addition, the extension side first annular section912protrudes toward the one side in the axial direction.

The extension side second annular section913is formed in an approximate ring shape on the outer side in the radial direction of the extension side first annular section912. In addition, the extension side second annular section913protrudes toward the one side in the axial direction. Moreover, a protrusion height of the extension side second annular section913is higher than the extension side first annular section912. In other words, a one side-end of the extension side second annular section913is positioned further on the one side than the extension side first annular section912.

The compression side oil channel914has a one side-oil port positioned on the outer side of the extension side second annular section913in the radial direction and another side-oil port positioned on the inner side of the compression side annular section911in the radial direction.

The extension side first oil channel915has a one side-oil port positioned on the inner side of the extension side first annular section912in the radial direction and another side-oil port positioned on the outer side of the compression side annular section911in the radial direction.

The extension side second oil channel916has a one side-oil port positioned between the extension side first annular section912and the extension side second annular section913and another side-oil port positioned at the opening91H of the third valve seat91. In addition, in the fourth embodiment, the extension side second oil channel916(a connecting flow channel) connects to the bypass oil channel951(a bypass channel, to be described later) separately from the compression side oil channel914and the extension side first oil channel915(a flow channel) inside the third valve seat91.

The compression side valve92is constituted by a disc-shaped metal plate material. In addition, the compression side valve92is configured so as to be capable of coming into contact with the compression side annular section911. Furthermore, the compression side valve92opens the compression side oil channel914when oil flows through the compression side oil channel914toward the second oil chamber Y2. Moreover, the compression side valve92always opens the other side of the extension side first oil channel915.

The extension side first valve93is constituted by a disc-shaped metal plate material. In addition, the extension side first valve93is configured so as to be capable of coming into contact with the extension side first annular section912. Furthermore, the extension side first valve93opens the extension side first oil channel915when oil flows through the extension side first oil channel915toward the first oil chamber Y1.

Moreover, the extension side first valve93is configured so as to be less deformable than the extension side second valve94. In the fourth embodiment, the extension side first valve93is configured so as not to open at least under oil pressure that applies when the extension side second valve94starts to open.

The extension side second valve94is constituted by a disc-shaped metal plate material. In addition, the extension side second valve94is configured so as to be capable of coming into contact with the extension side second annular section913. Furthermore, the extension side second valve94opens the extension side first oil channel915when oil flows through the extension side first oil channel915toward the first oil chamber Y1. Moreover, the extension side second valve94opens the extension side second oil channel916when oil flows through the extension side second oil channel916toward the first oil chamber Y1.

Together with the nut96, the bolt95sandwiches and holds the third valve seat91, the compression side valve92, the extension side first valve93, and the extension side second valve94. In addition, the bolt95includes the bypass oil channel951. One side of the bypass oil channel951communicates with the housing inner chamber31Y and another side thereof communicates with the extension side second oil channel916. Furthermore, the bypass oil channel951opposes a valve section1621of the damping force changing section160.

The damping force changing section160includes a housing161, a solenoid61which is provided on an inner side of the housing161, a plunger162which is provided on the inner side of the solenoid61in the radial direction, and a spring65.

The housing161holds the solenoid61on the inner side and is fixed to the other side of the housing31.

The plunger162includes the valve section1621on a one side-end thereof. The valve section1621is provided so as to be capable of advancing and retreating with respect to the bypass oil channel951of the bolt95due to the solenoid61. In addition, in the fourth embodiment, the valve section1621forms the throttle section160V which throttles a flow of oil between the valve section1621and the bypass oil channel951.

In addition, the damping force changing section160adjusts a throttle amount of a flow of oil through the bypass oil channel951in accordance with an amount by which the plunger162advances or retreats with respect to the bolt95. In the fourth embodiment, the throttle section160V forms a closed state where the flow of oil through the bypass oil channel951is stopped and an opened state where the flow of oil through the bypass oil channel951is allowed.

Moreover, with respect to the opened state, a throttle amount by the throttle section160V may be adjusted in a plurality of stages by adjusting a protrusion amount of the plunger162toward the one side in accordance with an amount of current supplied to the solenoid61.

Operations of Hydraulic Damping Device1According to Fourth Embodiment

FIGS. 13A and 13Bare explanatory diagrams of operations of the hydraulic damping device1according to the fourth embodiment.

Moreover, inFIGS. 13A and 13B, a flow of oil during a compression stroke will be depicted by a solid line and a flow of oil during an extension stroke will be depicted by a dashed line. In addition,FIG. 13Ais a diagram showing a case where a closed state is formed in the damping force changing section160.FIG. 13Bis a diagram showing a case where an opened state is formed in the damping force changing section160.

First, a flow of oil when the closed state is formed in the damping force changing section160will be described. In addition, hereinafter, descriptions applicable during a compression stroke and during an extension stroke will be respectively given in this order.

As indicated by a solid line arrow inFIG. 13A, when the piston constituting section330moves to the one side in the axial direction with respect to the cylinder11, oil in the first oil chamber Y1flows through the compression side oil channel914and flows out to the housing inner chamber31Y while pressing and opening the compression side valve92. In addition, the oil in the housing inner chamber31Y passes through the opening313and flows out to the second oil chamber Y2.

As described above, during a compression stroke in the closed state, a damping force is mainly generated by resistance created when oil flows through the compression side oil channel914and the compression side valve92.

As indicated by a dashed line arrow inFIG. 13A, when the piston constituting section330moves to the other side in the axial direction with respect to the cylinder11, oil in the second oil chamber Y2flows through the opening313, the housing inner chamber31Y, and the extension side first oil channel915and flows out to the inter-valve chamber93Y while pressing and opening the extension side first valve93. Furthermore, the oil in the inter-valve chamber93Y flows out to the first oil chamber Y1while pressing and opening the extension side second valve94.

As described above, during an extension stroke in the closed state, a damping force is mainly generated by resistance created when oil flows through the extension side first oil channel915, the extension side first valve93, and the extension side second valve94.

Next, a flow of oil when the opened state is formed in the damping force changing section160will be described.

As shown inFIG. 13B, in the opened state, a state exists where the valve section1621of the plunger162has separated from the bypass oil channel951and the throttle section160V has opened.

As indicated by a solid arrow inFIG. 13B, circumstances during a compression stroke in the opened state are similar to the circumstances during a compression stroke in the closed state. In other words, during a compression stroke in the opened state, a damping force is mainly generated by resistance created when oil flows through the compression side oil channel914and the compression side valve92.

As indicated by a dashed line arrow inFIG. 13B, when the piston constituting section330moves to the one side in the axial direction with respect to the cylinder11, oil in the second oil chamber Y2flows through the opening313, the throttle section160V, and the bypass oil channel951. In addition, the oil in the bypass oil channel951flows into the extension side second oil channel916and flows out to the first oil chamber Y1while pressing and opening the extension side second valve94. In this manner, in the opened state, oil flows so as to bypass the flow of oil which presses and opens the extension side first valve93.

As described above, during an extension stroke in the opened state, a damping force is mainly generated by resistance created when oil flows through the extension side second oil channel916and the extension side second valve94. Furthermore, the damping force generated in the opened state is smaller than the damping force generated in the closed state.

As described above, even with the hydraulic damping device1according to the fourth embodiment, a magnitude of a generated damping force can be changed using the damping force changing section160. In addition, in the fourth embodiment, the throttle section160V is similarly formed further on the outer side than the valve (the compression side valve92) with respect to the third valve seat91. Accordingly, machining when manufacturing the hydraulic damping device1is simplified.

Fifth Embodiment

FIG. 14is an overall configuration diagram of a hydraulic damping device1according to a fifth embodiment.

Moreover, in the fifth embodiment, components similar to those of the other embodiments described above will be assigned same numbers and detailed descriptions thereof will be omitted.

First, an outline of the hydraulic damping device1according to the fifth embodiment will be described.

As shown inFIG. 14, the hydraulic damping device1(a pressure damping device) includes: a cylinder11which extends from one side toward another side and which houses oil (a fluid); a piston section100(a partitioning section) which is provided so as to be movable in an axial direction in the cylinder11and which partitions a space in the cylinder11into a first oil chamber Y1(a first chamber) and a second oil chamber Y2(a second chamber); a valve seat41(a flow channel formation section) in which a compression side oil channel416(a flow channel) through which the oil flows is formed in conjunction with a movement of the piston section100; a compression side second valve43(a valve section) which controls a flow of the oil in the compression side oil channel416of the valve seat41; a bypass oil channel471(a bypass channel) which forms a flow of the oil that bypasses the flow of the oil flowing through the compression side oil channel416while opening the compression side second valve43; and a throttle section60V which throttles the flow of the oil through the bypass oil channel471further on the outer side than the compression side second valve43with respect to the valve seat41.

As shown inFIG. 14, the hydraulic damping device1according to the fifth embodiment includes a piston section100in place of the piston constituting section30according to the first embodiment and includes a bottom valve section430in place of the bottom valve section70according to the first embodiment.

The piston section100is attached to a one side-end of the rod member21. In addition, in conjunction with movements of the rod member21on the one side and on the other side, the piston section100generates flows of oil between the first oil chamber Y1and the second oil chamber Y2and between the first oil chamber Y1and the reservoir chamber R.

The bottom valve section430shares a basic configuration with the piston constituting section30according to the first embodiment. Furthermore, the bottom valve section430is provided on one side-ends of the cylinder11and the outer cylindrical body12.

Moreover, even with the fifth embodiment configured as described above, the hydraulic damping device1can be machined easily.

Sixth Embodiment

FIG. 15is an overall configuration diagram of a hydraulic damping device1according to a sixth embodiment.

Moreover, in the sixth embodiment, components similar to those of the other embodiments described above will be assigned same numbers and detailed descriptions thereof will be omitted.

The hydraulic damping device1according to the sixth embodiment includes a damping force generating unit530. The damping force generating unit530shares a basic configuration with the piston constituting section30according to the first embodiment. In addition, the damping force generating unit530is provided as a separate body with respect to the cylinder section10and includes a second cylinder530C which houses oil.

Next, a general configuration of the hydraulic damping device1according to the sixth embodiment will be described.

As shown inFIG. 15, the hydraulic damping device1(a pressure damping device) includes: a cylinder11which extends from one side toward another side and which houses oil (a fluid); a piston section100(a partitioning section) which is provided so as to be movable in an axial direction in the cylinder11and which partitions a space in the cylinder11into a first oil chamber Y1(a first chamber) and a second oil chamber Y2(a second chamber); a valve seat41(a flow channel formation section) in which a compression side oil channel416(a flow channel) through which the oil flows is formed in conjunction with a movement of the piston section100; a compression side second valve43(a valve section) which controls a flow of the oil in the compression side oil channel416of the valve seat41; a bypass oil channel471(a bypass channel) which forms a flow of the oil that bypasses the flow of the oil flowing through the compression side oil channel416while opening the compression side second valve43; and a throttle section60V which throttles the flow of the oil through the bypass oil channel471further on the outer side than the compression side second valve43with respect to the valve seat41.

As shown inFIG. 15, in the hydraulic damping device1according to the sixth embodiment, a first external oil chamber C1is formed on the one side of the housing31and a second external oil chamber C2is formed on the other side of the housing31. In addition, the first external oil chamber C1is connected to a communicating port11P which communicates with the first oil chamber Y1of the cylinder11. Furthermore, in the sixth embodiment the second external oil chamber C2is connected to a communicating port12P which communicates with the second oil chamber Y2of the cylinder11.

Moreover, even with the sixth embodiment configured as described above, the hydraulic damping device1can be machined easily.

As described above, even in the second to sixth embodiments, instead of directly operating the valves by electric control, the valves are indirectly controlled by switching flows of oil in oil channels by electric control.

Moreover, for example, the hydraulic damping device1according to the first embodiment may be configured so as to detect a rotational position of the shutter valve64based on an electromagnetic amount that is determined by a positional relationship between the solenoid61and the shutter valve64. In addition, the hydraulic damping devices according to the second to fifth embodiments may similarly be provided with a configuration for detecting a rotational position.

As described earlier with reference toFIG. 3, depths in the axial direction of the first depressed section631, the second depressed section632, and the third depressed section633of the second cam housing63differ from one another. Therefore, a position of the shutter valve64in the axial direction differs depending on which depressed section the guided section641fits into. In addition, inductance varies depending on a position of the shutter valve64with respect to the solenoid61. In consideration thereof, in the first embodiment, a rotational position of the shutter valve64may be indirectly detected based on a change in an electromagnetic amount such as an amount of current in the solenoid61.

In addition, the damping force changing section60according to the first embodiment may be applied to the fourth embodiment. Furthermore, as described as the first modification, a configuration similar to the valve seat41constructed by joining together split members can be respectively applied to the valve seats according to the third to sixth embodiments. Moreover, as described as the second modification, a configuration not provided with the housing31can be respectively applied to the third to sixth embodiments.

Furthermore, although the hydraulic damping device1has a so-called double-tube structure in the first to sixth embodiments described above, the hydraulic damping device1is not limited thereto and may have a so-called triple-tube structure. Moreover, the bottom valve section70according to the first to fourth embodiments and the sixth embodiment as well as the piston section100according to the fifth and sixth embodiments are not limited to the structures described in the embodiments above and may have other shapes and configurations as long as functions as a damping mechanism are provided.

EXPLANATION OF REFERENCE NUMERALS

1hydraulic damping device (an example of a pressure damping device)11cylinder (an example of a cylinder)30piston constituting section31housing (an example of a partitioning section)41valve seat (an example of a flow channel formation section)42compression side first valve (an example of an inner valve section)43compression side second valve (an example of an outer valve section)60damping force changing section60V throttle section (an example of a throttle section)61solenoid (an example of a driving section)64shutter valve (an example of a protruding member)83damping valve (an example of a two-way valve)811bypass oil channel (an example of a bypass channel)