STEERING DEVICE AND SHIP

A steering device includes: a flow passage forming member including a first flow passage connecting to a first chamber and a second flow passage connecting to a second chamber; a movable member movable relative to the flow passage forming member; a seal member configured to seal a space between the movable member and the flow passage forming member when the seal member is in contact with the movable member and the flow passage forming member; an operation part capable of rotating an outboard motor; and a resistance reducing part configured to reduce a flow resistance so that a fluid flows between the first and second flow passages even with a pressure generated in the first chamber or the second chamber due to an operation of the operation part by a load equal to or lower than a predetermined load, when sealing is not made by the seal member.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority to Japanese Patent Application No. 2021-009686, filed on Jan. 25, 2021, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a steering device, and a ship.

BACKGROUND OF THE INVENTION

A ship includes a steering device configured to control a traveling direction of a ship body by swinging an outboard motor right and left. For example, JP-A-2020-185885 discloses technology about the steering device. The steering device disclosed in JP-A-2020-185885 includes a cylinder, a motor, a hydraulic source, a main valve, and an oil storage tank. The cylinder is demarcated into a first chamber and a second chamber by a piston. The steering device also includes a check valve that is opened when a hydraulic pressure to the cylinder rapidly increases when supplying an operating oil to a hydraulic circuit so that the piston slides from the first chamber-side toward the second chamber-side. The steering device also includes a check valve that is opened when the hydraulic pressure to the cylinder rapidly increases when supplying the operating oil to the hydraulic circuit so that the piston slides from the second chamber-side toward the first chamber-side. The steering device also includes a manual valve configured to enable manual steering of manually changing the traveling direction of the ship body by opening the valve.

An operation load when manually changing the traveling direction of the ship body is preferably small.

An object of the present invention is to provide a steering device and the like capable of reducing an operation load when manually changing a traveling direction of a ship body.

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided a steering device including: a flow passage forming member including a first flow passage connecting to a first chamber in a cylinder and a second flow passage connecting to a second chamber in the cylinder; a movable member provided to be movable relative to the flow passage forming member and capable of being arranged between the first flow passage and the second flow passage; a seal member arranged between the movable member and the flow passage forming member and configured to seal a space between the movable member and the flow passage forming member when the seal member is in contact with the movable member and the flow passage forming member; an operation part capable of rotating an outboard motor when a pressure in the first chamber or the second chamber is increased and capable of applying a pressure to the first chamber or the second chamber to rotate the outboard motor when the operation part is manually operated; and a resistance reducing part configured to reduce a flow resistance so that a fluid flows between the first flow passage and the second flow passage even with a pressure generated in the first chamber or the second chamber due to an operation of the operation part by a load equal to or lower than a predetermined load, when sealing is not made by the seal member.

DETAILED DESCRIPTION OF THE INVENTION

Hereinbelow, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that, the embodiments of the present invention to be described below are just exemplary, and the present invention is not limited to the embodiments.

First Embodiment

FIG. 1depicts an example of a schematic configuration of a ship100in accordance with a first embodiment.

FIG. 2depicts an example of a cylinder4, an arm9, a pump unit3and the like, as seen in a direction II ofFIG. 1.

FIG. 3depicts an example of a hydraulic circuit of a steering device1.

The ship100includes a ship body101, an outboard motor102mounted to the ship body101and configured to generate a propulsion force, and a steering device1configured to change a traveling direction of the ship100by using an oil that is an example of the fluid. In descriptions below, a traveling direction in a state where the ship100travels in a straight line may be referred to as the front, an opposite direction to the traveling direction may be referred to as the rear, the left side with respect to the traveling direction may be referred to as the left, and the right side with respect to the traveling direction may be referred to as the right.

The steering device1has a ring-shaped steering wheel2provided to a front part of the ship body101. The steering device1also includes a pump unit3configured to supply the oil according to rotation of the steering wheel2, and a cylindrical cylinder4into which the oil supplied by the pump unit3is caused to flow, which are provided to a rear part of the ship body101. The steering device1also includes a piston5by which a space in the cylinder4is demarcated into a first chamber Y1and a second chamber Y2, and a rod6axially penetrating the cylinder4and holding the piston5. The steering device1also includes a piping7connected to the pump unit3and the first chamber Y1of the cylinder4, and a piping8connected to the pump unit3and the second chamber Y2of the cylinder4. The oil is supplied to any one of the piping7and the piping8, according to a rotation direction of the steering wheel2. The steering device1also includes a flat plate-shaped arm9having one end attached to the outboard motor102, and a link10connected to the arm9and the cylinder4.

As shown inFIG. 3, the pump unit3has a motor20, a pump21having a pair of gears and configured to be driven to discharge the oil by the motor20, and a tank22in which the oil is stored. A flow passage31leading to the first chamber Y1and a flow passage32leading to the second chamber Y2are formed between the pump21and the cylinder4.

The pump unit3includes a main valve23arranged to straddle the flow passage31and the flow passage32and configured to switch a direction of the oil flowing toward the first chamber Y1or the second chamber Y2.

The pump unit3also includes a check valve24arranged on a supply path33through which the oil is supplied from the tank22to the pump21, and a check valve25arranged on a supply path34through which the oil is supplied from the tank22to the pump21. The supply path33is connected to a flow passage31A leading from the pump21to the main valve23. The supply path34is connected to a flow passage32A leading from the pump21to the main valve23.

The pump unit3also includes a first valve41that opens when a pressure in a flow passage31B leading from the main valve23to the first chamber Y1becomes equal to or higher than a preset pressure, thereby relieving the oil in the flow passage31B to a flow passage32B leading from the main valve23to the second chamber Y2. The pressure in the flow passage31B becomes equal to or higher than the preset pressure when an external force is applied to the outboard motor102and the piston5is thus rapidly moved toward the first chamber Y1, for example.

The pump unit3also includes a second valve42that opens when a pressure in the flow passage32B becomes equal to or higher than a preset pressure, thereby relieving the oil in the flow passage32B to the flow passage31B. The pressure in the flow passage32B becomes equal to or higher than the preset pressure when an external force is applied to the outboard motor102and the piston5is thus rapidly moved toward the second chamber Y2, for example.

The pump unit3also includes a manual valve43that is arranged on an flow passage between the flow passage31B and the flow passage32B and can be manually opened and closed by a user.

The pump unit3also includes a housing30(refer toFIG. 2) in which the pump21, the main valve23, the check valve24, the check valve25, the first valve41, the second valve42and the manual valve43are accommodated. The housing30is formed with the flow passage31A and the flow passage32A. The housing30is connected to the piping7and the piping8. A part of the flow passage31B is constituted by the piping7, and the flow passage31B from the main valve23to the piping7is formed in the housing30. A part of the flow passage32B is constituted by the piping8, and the flow passage32B from the main valve23to the piping8is formed in the housing30.

In the steering device1configured as described above, when the steering wheel2is rotated in a clockwise direction, the oil is supplied to the second chamber Y2by the pump21, so that a pressure in the second chamber Y2is increased. Thereby, the cylinder4is moved leftward with respect to the piston5whose position is fixed via the rod6, so that the outboard motor102is rotated in an A direction (counterclockwise direction) shown inFIG. 1. As a result, the ship body101travels rightward. On the other hand, when the steering wheel2is rotated in a counterclockwise direction, the oil is supplied to the first chamber Y1by the pump21, so that a pressure in the first chamber Y1is increased. Thereby, the cylinder4is moved rightward with respect to the piston5, so that the outboard motor102is rotated in a B direction (clockwise direction) shown inFIG. 1. As a result, the ship body101travels leftward.

In the below, the first valve41, the second valve42, and the manual valve43are described.

FIG. 4depicts an example of a schematic configuration of a valve unit50in accordance with the first embodiment.

The pump unit3of the first embodiment includes a valve unit50where the second valve42and the manual valve43are integrally constituted.

The valve unit50includes a spherical valve body51, a movable member52on which the valve body51is seated, a holding member53configured to hold the valve body51, a coil-shaped spring54, and a cap55for plugging a through-hole35formed in the housing30. The valve unit50also includes a handle57that is gripped for operation with a hand by a user, and an annular seal member58configured to seal a gap between the movable member52and the housing30.

In the valve unit50, the movable member52is press-fitted into the cap55and is thus integrated in a state where the spring54, the holding member53and the valve body51are accommodated in the cap55. The handle57is mounted to the cap55. The valve unit50is inserted in the through-hole35formed in the housing30from the movable member52-side. The valve unit50is arranged so that the movable member52is on the front side and the handle57is on the rear side with respect to the ship body101.

The movable member52has a cylindrical first part521provided on the forefront side, a cylindrical second part522provided behind the first part521, a cylindrical third part523provided behind the second part522, and a cylindrical fourth part524provided behind the third part523.

The first part521is formed with a through-hole525for communicating an inside and an outside. The through-hole525may be one or may be formed in plural with equal intervals in a circumferential direction.

An inner diameter of the second part522is the same as an inner diameter of the first part521, and an outer diameter of the second part522is larger than an outer diameter of the first part521.

An inner diameter of the third part523is larger than the inner diameter of the second part522, and an outer diameter of the third part523is the same as the outer diameter of the second part522.

An inner diameter of the fourth part524is the same as the inner diameter of the third part523, and an outer diameter of the fourth part524is smaller than the outer diameter of the third part523.

An end portion on a rear side of the fourth part524is formed with a concave portion526recessed from an inner peripheral surface. An end portion on a front side of the concave portion526is formed with a seating surface527on which the valve body51is seated and which is inclined relative to a center line C1.

The holding member53is a columnar member having an outer diameter smaller than an inner diameter of the spring54. The holding member53has a protrusion part531provided at an end portion on a front side and protruding outward from an outer peripheral surface. An outer diameter of the protrusion part531is larger than a center diameter of the spring54, and is equal to or smaller than the outer diameter of the fourth part524of the movable member52. The protrusion part531supports an end portion on a front side of the spring54.

The cap55has a cylindrical tubular part551provided on a front side, a columnar first pillar-shaped part561provided behind the tubular part551, and a columnar second pillar-shaped part562provided behind the first pillar-shaped part561.

An inner diameter of the tubular part551is larger than the outer diameter of the spring54and the outer diameter of the protrusion part531of the holding member53, so that the spring54, the holding member53and the valve body51are accommodated in the tubular part551.

The inner diameter of the tubular part551is smaller than the outer diameter of the fourth part524of the movable member52, and an outer diameter of the tubular part551is substantially the same as the outer diameter of the third part523of the movable member52. The tubular part551and the movable member52are fitted (press-fitted) by interference-fit.

In the tubular part551, a through-hole553for communicating an inside and an outside is formed behind a part in which the fourth part524of the movable member52is fitted. In the tubular part551, a male screw554that is fastened to a female screw355formed in the through-hole35is formed at a part behind the through-hole553.

The first pillar-shaped part561is formed with a groove563recessed from an outer peripheral surface over an entire circumference. In the groove563, an O-ring564for sealing a space between an outer peripheral surface of the cap55and an inner peripheral surface of the through-hole35is fitted.

An end portion on a rear side of the second pillar-shaped part562is formed with a female screw565. A bolt59is fastened to the female screw565, so that the handle57is attached to the second pillar-shaped part562.

The seal member58has an inner diameter that is larger than the outer diameter of the first part521of the movable member52, and an outer diameter that is substantially the same as the outer diameter of the second part522.

The through-hole35has a columnar first hole351formed on a front side and a columnar second hole352formed on a rear side and having a diameter larger than a diameter of the first hole351. The first hole351communicates with the flow passage32B. The second hole352communicates with the flow passage31B via a connection hole353formed in a direction of intersecting with the center line C1of the second hole352. Note that, an opening on a front side, which is opposite to a side in which the valve unit50is inserted, of the through-hole35is closed.

The valve unit50configured as described above is mounted to the housing30by operating the handle57to fasten the male screw554of the cap55to the female screw355formed in the through-hole35. The seal member58is attached to an outer side of the first part521of the movable member52, and the seal member58is arranged between the second part522of the movable member52and the housing30.

FIG. 5depicts a state where the valve unit50is inserted up to the innermost side.

The user can change a screwing depth of the valve unit50to the housing30by operating the handle57. As shown inFIG. 5, the user can insert forward the valve unit50until the seal member58comes into contact with the second part522of the movable member52and the housing30. On the other hand, the user can move rearward the valve unit50until an end face on the rear side of the first pillar-shaped part561of the cap55is butted against a clip354attached to the housing30.

In a state (hereinbelow, also referred to as ‘first state’) where the seal member58is in contact with the second part522of the movable member52and the housing30, the seal member58seals the gap between the movable member52and the housing30. For this reason, in the first state, the oil is difficult to flow between the flow passage31B and the flow passage32B through a ring-shaped flow passage R1between an outer peripheral surface of the first part521of the movable member52and an inner peripheral surface of the first hole351of the through-hole35of the housing30.

In addition, in the first state, the valve body51is applied with a spring force of the spring54via the holding member53and is thus seated on the seating surface527of the movable member52, so that the valve body51is not opened unless the pressure in the flow passage32B becomes equal to or higher than a preset pressure. The preset pressure is set as a value that the pressure in the flow passage32B is difficult to reach simply by manually operating the arm9.

As a result, it is difficult to rotate the outboard motor102by manually operating the arm9in a direction in which the piston5moves toward the second chamber Y2-side.

Note that, in the first state, when the pressure in the flow passage32B becomes equal to or higher than the preset pressure, the valve body51moves rearward against the spring force of the spring54, so that a gap is formed between the valve body51and the seating surface527of the movable member52. For this reason, the oil flows from the flow passage32B to the flow passage31B through an inside of the movable member52, the gap between the valve body51and the seating surface527of the movable member52, and the through-hole553of the tubular part551of the cap55.

On the other hand, as shown inFIG. 4, in a state (hereinbelow, also referred to as ‘second state’) where the seal member58is not in contact with the second part522of the movable member52and the housing30, the seal member58does not seal the gap between the movable member52and the housing30. Therefore, the oil can easily flow between the flow passage31B and the flow passage32B through the ring-shaped flow passage R1. As a result, when the user unfastens the male screw554and takes out the valve unit50rearward, it is possible to rotate the outboard motor102more easily by manually operating the arm9, as compared to the first state.

In addition, when the valve unit50is moved until the through-hole525formed in the first part521of the movable member52is located behind the first hole351of the housing30, the oil flows from the flow passage32B to the flow passage31B through the through-hole525. An area of the through-hole525is greater than a flow area of the ring-shaped flow passage R1. As a result, since a flow resistance of the oil flowing between the flow passage31B and the flow passage32B is reduced, an operation load is reduced when manually changing the traveling direction of the ship body101by operating the arm9.

From the above, the valve body51, the movable member52, the holding member53, the spring54, the cap55, the seal member58and the housing30constitute the second valve42. The movable member52, the cap55, the handle57, the seal member58and the housing30constitute the manual valve43that can open and close the flow passage between the flow passage31B and the flow passage32B by the user's operation.

Note that, the clip354is provided in a position where the end face on the rear side of the first pillar-shaped part561of the cap55is butted when the end portion on the front side of the first part521of the movable member52is located in the first hole351of the housing30. This is to locate the seal member58on the outer side of the first part521even when the male screw554is unfastened and the valve unit50is taken out rearward by the user.

FIG. 6depicts an example of a schematic configuration of the first valve41.

The first valve41includes a spherical valve body61, a movable member62on which the valve body61is seated, a holding member63configured to hold the valve body61, a coil-shaped spring64, and a cap65for plugging a through-hole36formed in the housing30. The first valve41also includes an annular seal member68for sealing a gap between the movable member62and the housing30.

Since the valve body61, the movable member62, the holding member63and the spring64are each similar to the valve body51, the movable member52, the holding member53and the spring54of the valve unit50, the detailed descriptions thereof are omitted.

The cap65is different from the cap55, in that it does not have the second pillar-shaped part562and the handle57is not attached thereto.

The first valve41is inserted in the through-hole36. The through-hole36has a columnar first hole361formed on a rear side and a columnar second hole362formed on a front side and having a diameter larger than a diameter of the first hole361. The first hole361is configured to communicate with the flow passage31B. The second hole362is configured to communicate with the flow passage32B via a connection hole (not shown) formed in a direction of intersecting with a center line of the second hole362.

The first valve41is inserted in the through-hole36until the seal member68comes contact with the movable member62and the housing30. The valve body61is applied with a spring force of the spring64via the holding member63and is thus in contact with a seating surface627of the movable member62. When the pressure in the flow passage31B becomes equal to or higher than the preset pressure, the valve body61separates from the seating surface627. When the pressure in the flow passage31B becomes equal to or higher than the preset pressure, the valve body61is moved forward against the spring force of the spring64, so that a gap is formed between the valve body61and the seating surface627of the movable member62. As a result, the oil flows from the flow passage31B to the flow passage32B through an inside of the movable member62, the gap between the valve body61and the seating surface627of the movable member62, and a through-hole653of a tubular part651of the cap65.

The preset pressure at which the valve body61starts to move is set as a value that the pressure in the flow passage31B is difficult to reach simply by manually operating the arm9.

As a result, it is difficult to rotate the outboard motor102by manually operating the arm9in a direction in which the piston5moves toward the first chamber Y1-side.

However, as shown inFIG. 4, the user unfastens the male screw554to take out the valve unit50rearward, and causes the seal member58not to seal the gap between the movable member52and the housing30, thereby enabling the oil to easily flow between the flow passage31B and the flow passage32B. Thereby, it is possible to easily rotate the outboard motor102by manually operating the arm9.

As described above, the steering device1includes the housing30as an example of the flow passage forming member where the flow passage31B as an example of the first flow passage connecting to the first chamber Y1in the cylinder4and the flow passage32B as an example of the second flow passage connecting to the second chamber Y2in the cylinder4are formed. The steering device1also includes the movable member52as an example of the movable member provided to be movable relative to the housing30and capable of being arranged between the flow passage31B and the flow passage32B. The steering device1also includes the seal member58arranged between the movable member52and the housing30and sealing a space between the movable member52and the housing30when the seal member58is in contact with the movable member52and the housing30. The steering device1also includes the arm9as an example of the operation part capable of rotating the outboard motor102when the pressure in the first chamber Y1or the second chamber Y2is increased and applying a pressure to the first chamber Y1or the second chamber Y2to rotate the outboard motor102when it is manually operated. The steering device1also includes the through-hole525as an example of the resistance reducing part that reduces a flow resistance so that the oil as an example of the fluid flows between the flow passage31B and the flow passage32B, when the sealing is not made by the seal member58.

Here, an area S (cm2) of the through-hole525of the first part521of the movable member52is determined so that a manual steering load F of the arm9is equal to or lower than a preset upper limit load Fm. More specifically, the area S is calculated using following equations (1), (2) and (3). Note that, the upper limit load Fm may be 100(N), for example.

Q is a flow rate (cm3/sec) of the oil to flow per a unit time and is determined by the equation (2). P1is a pressure (MPa) on a high pressure-side (for example, the pressure in the flow passage32B when the arm9is steered so that the piston5moves toward the second chamber Y2) and is a value determined by the equation (3). C is a resistance coefficient of a flow passage, G is the acceleration of gravity (=980 cm/sec), P2is a pressure (MPa) on a lower pressure-side, and r is a specific gravity (Kgf/cm3).

Lp is a stroke (cm) of the piston5, and t is an operating time (sec) of the arm9(piston5).

k is a coefficient corresponding to a length of the arm9and Sp is a sectional area (cm2) of the piston5.

In the case of the area S=0.0322 (cm2), when the through-hole525is one, the hole diameter is 0.202 (cm), and when the through-hole525is two, the hole diameter is 0.143 (cm). When the two through-holes525are provided and the hole diameter is set to 0.15 (cm), the manual steering load F can be made equal to or lower than the upper limit load Fm.

As described above, when the sealing is not made by the seal member58, the through-hole525of the first part521of the movable member52reduces the flow resistance so that the oil flows between the flow passage31B and the flow passage32B even with the pressure generated in the first chamber Y1or the second chamber Y2due to the operation of the arm9with the load equal to or lower than the upper limit load Fm.

The flow resistance reducing function of the through-hole525is exhibited as the through-hole525is provided as described above. That is, in the steering device1, the movable member52has the first part521as an example of the cylindrical part that is fitted in the first hole351as an example of the hole formed in the housing30and communicating with the flow passage32B. When the sealing is made by the seal member58, the through-hole525is located inside the first hole351, and when the sealing is not made by the seal member58, the through-hole525is located outside the first hole351so that the fluid flows between the flow passage31B and the flow passage32B via the through-hole525.

In the steering device1, the movable member52is cylindrical, and has the seating surface527provided at the end portion on the opposite side to the flow passage32B in the direction of the center line C1and being in contact with the spherical valve body51. The steering device1has the cap55configured to accommodate therein the valve body51, the holding member53as an example of the pressing part for pressing the valve body51to the seating surface527and the spring54together with the movable member52, and having the through-hole553formed on a further opposite side to the flow passage32B than the valve body51and provided as an example of the communication hole for communicating an inside and an outside. In other words, the steering device1includes the valve unit50where the second valve42and the manual valve43are integrally provided. For this reason, as compared to a configuration where the second valve42and the manual valve43are provided as separate bodies, the steering device1has a simpler configuration and is more lightweight.

Second Embodiment

FIG. 7depicts an example of a schematic configuration of a manual valve243in accordance with a second embodiment.

A steering device200of the second embodiment is different from the steering device1of the first embodiment, in a manual valve243corresponding to the manual valve43. The manual valve243is different from the manual valve43, in a movable member252corresponding to the movable member52. Hereinbelow, differences from the steering device1are described. The parts having the same functions between the steering device1and the steering device200are denoted with the same reference signs, and the detailed descriptions thereof are omitted.

The movable member252is different from the movable member52of the first embodiment, in a first part2521corresponding to the first part521. The first part2521is not formed with the through-hole525that is formed in the first part521. An outer diameter of the first part2521is smaller than the outer diameter of the first part521. For this reason, in the manual valve243, a flow area of a ring-shaped flow passage R2between an outer peripheral surface of the first part2521and the inner peripheral surface of the first hole351of the through-hole35of the housing30is greater than the flow area of the ring-shaped flow passage R1of the first embodiment.

For this reason, when the male screw554(refer toFIG. 4) is unfastened by the user and the seal member58does not seal the gap between the movable member252and the housing30, the resistance when the oil flows between the flow passage31B and the flow passage32B through the ring-shaped flow passage R2is reduced, as compared to the resistance when the oil flows through the ring-shaped flow passage R1. As a result, even when the first part2521is not formed with a through-hole corresponding to the through-hole525, the operation load when manually operating the arm9is reduced.

Here, a gap h2(cm) (=(the outer diameter d (cm) of the first part2521−the diameter (D) (cm) of the first hole351)/2) between the outer peripheral surface of the first part2521and the inner peripheral surface of the first hole351of the through-hole35of the housing30is determined so that the manual steering load F of the arm9is equal to or lower than the upper limit load Fm. More specifically, the gap h2is calculated using a following equation (4).

Q and P1are values determined by the above equations (2) and (3). μ is a viscosity (Pa·sec) of the oil, and L is a wrap length (cm) of the first part2521and the first hole351.

In a case of Fm=100 (N), D=0.325 (cm), P2=0 (MPa) and L=0.1 (cm), the gap h2=0.062 (cm) is calculated, and d0=0.201 (cm) is calculated using an equation of d0(cm)=D−2×h2. The outer diameter d of the first part2521is set smaller than d0, so that the manual steering load F can be made equal to or lower than the upper limit load Fm.

As described above, in the steering device200, the movable member252has the first part2521as an example of the cylindrical part that is fitted in the first hole351formed in the housing30and communicating with the flow passage32B. The ring-shaped flow passage R2between the outer peripheral surface of the first part2521and the inner peripheral surface of the first hole351functions as the resistance reducing part that reduces the flow resistance so that the oil flows between the flow passage31B and the flow passage32B even with the pressure generated in the first chamber Y1or the second chamber Y2due to the operation of the arm9with the load equal to or lower than the upper limit load, when the sealing is not made by the seal member58.

Since the inner diameter of the first part2521is the same as the inner diameter of the first part521, the resistance when the oil passes through the inside of the first part2521can be made to be the same as the resistance when the oil passes through the inside of the first part521. For this reason, also in the second embodiment, the second valve42is opened when the pressure in the flow passage32B becomes equal to or higher than the preset pressure, so that the oil in the flow passage32B can be relived to the flow passage31B. In the meantime, the inner diameter of the first part2521may be set small within a range in which the second valve42can be opened when the pressure in the flow passage32B becomes equal to or higher than the preset pressure.

Note that, the first part2521may also be formed with a through-hole corresponding to the through-hole525. Thereby, as compared to the configuration where the movable member252is used, the resistance when the oil flows between the flow passage31B and the flow passage32B is reduced. As a result, the operation load when manually operating the arm9is reduced.

Third Embodiment

FIG. 8depicts an example of a schematic configuration of a manual valve343in accordance with a third embodiment.

A steering device300of the third embodiment is different from the steering device1of the first embodiment, in a manual valve343corresponding to the manual valve43. The manual valve343is different from the manual valve43, in a movable member350corresponding to the movable member52and a housing330corresponding to the housing30. Hereinbelow, differences from the steering device1are described. The parts having the same functions between the steering device1and the steering device300are denoted with the same reference signs, and the detailed descriptions thereof are omitted.

The movable member350is different from the movable member52, in a first part3521corresponding to the first part521. The first part3521is not formed with the through-hole525that is formed in the first part521.

The housing330is different from the housing30, in a through-hole335corresponding to the through-hole35. The through-hole335has a columnar first hole3351corresponding to the first hole351, and the second hole352. A diameter of the first hole3351is larger than the diameter of the first hole351.

For this reason, in the manual valve343, a flow area of a ring-shaped flow passage R3between an outer peripheral surface of the first part3521and an inner peripheral surface of the first hole3351of the through-hole335of the housing330is greater than the flow area of the ring-shaped flow passage R1of the first embodiment.

For this reason, when the male screw554(refer toFIG. 4) is unfastened by the user and the seal member58does not seal the gap between the movable member350and the housing330, the resistance when the oil flows between the flow passage31B and the flow passage32B through the ring-shaped flow passage R3is reduced, as compared to the resistance when the oil flows through the ring-shaped flow passage R1. As a result, even when the first part3521is not formed with a through-hole corresponding to the through-hole525, the operation load when manually operating the arm9is reduced.

Here, a gap h3(cm) (=(the outer diameter d (cm) of the first part3521−the diameter (D) (cm) of the first hole3351)/2) between the outer peripheral surface of the first part3521and the inner peripheral surface of the first hole3351of the through-hole335of the housing330is determined so that the manual steering load F of the arm9is equal to or lower than the upper limit load Fm. More specifically, the gap h3is calculated using a following equation (5).

Q and P1are values determined by the above equations (2) and (3). μ is a viscosity (Pa·sec) of the oil, and L is a wrap length (cm) of the first part3521and the first hole3351.

In a case of Fm=100 (N), D=0.325 (cm), P2=0 (MPa) and L=0.1 (cm), the gap h3=0.053 (cm) is calculated, and D0=0.431 (cm) is calculated using an equation of D0(cm)=d+2×h2. The outer diameter D of the first hole3351is set larger than D0, so that the manual steering load F can be made equal to or lower than the upper limit load Fm.

As described above, in the steering device300, the movable member350has the first part3521as an example of the cylindrical part that is fitted in the first hole3351formed in the housing330and communicating with the flow passage32B. The ring-shaped flow passage R3between the outer peripheral surface of the first part3521and the inner peripheral surface of the first hole3351functions as the resistance reducing part that reduces the flow resistance so that the oil flows between the flow passage31B and the flow passage32B even with the pressure generated in the first chamber Y1or the second chamber Y2due to the operation of the arm9with the load equal to or lower than the upper limit load, when the sealing is not made by the seal member58.

In addition, since the movable member62and the movable member350of the first valve41can be made to be the same, it is possible to reduce the number of components of the steering device300.

Note that, the first part3521may also be formed with a through-hole corresponding to the through-hole525. Thereby, as compared to the configuration where the movable member350is used, the resistance when the oil flows between the flow passage31B and the flow passage32B is reduced.

In addition, the movable member252of the second embodiment may also be used instead of the movable member350. Thereby, as compared to the configuration where the movable member350is used, the resistance when the oil flows between the flow passage31B and the flow passage32B is reduced. As a result, the operation load when manually operating the arm9is reduced.

Fourth Embodiment

FIG. 9depicts an example of a schematic configuration of a manual valve443in accordance with a fourth embodiment.

A steering device400of the fourth embodiment is different from the steering device1of the first embodiment, in a manual valve443corresponding to the manual valve43. The manual valve443is different from the manual valve43of the first embodiment, in a movable member452corresponding to the movable member52, a seal member458corresponding to seal member58and a housing430corresponding to the housing30. Hereinbelow, differences from the steering device1are described. The parts having the same functions between the steering device1and the steering device400are denoted with the same reference signs, and the detailed descriptions thereof are omitted.

The movable member452is different from the movable member52, in a second part4522corresponding to the second part522. An outer diameter of the second part4522is smaller than the outer diameter of the second part522. That is, the outer diameter of the second part4522is smaller than the outer diameter of the third part523, and the outer diameters are larger in order of the first part521, the second part4522and the third part523in the flow direction of the oil from the flow passage32B toward the flow passage31B.

An outer diameter of the seal member458is smaller than the outer diameter of the seal member58and is substantially the same as the outer diameter of the second part4522.

The housing430is different from the housing30, in a through-hole435corresponding to the through-hole35. The through-hole435has the first hole351, and a second hole4352corresponding to the second hole352. The through-hole435is also formed with a columnar first intermediate hole4353having a diameter larger than the diameter of the first hole351and a truncated conical second intermediate hole4354formed behind the first intermediate hole4353and having an outer diameter that becomes larger in the flow direction of the oil from the flow passage32B toward the flow passage31B, between the first hole351and the second hole4352. That is, the diameter of the through-hole435becomes larger in order of the first hole351, the first intermediate hole4353, the second intermediate hole4354and the second hole4352in the flow direction of the oil from the flow passage32B toward the flow passage31B.

For this reason, when the male screw554(refer toFIG. 4) is unfastened by the user and the seal member458does not seal a gap between the movable member452and the housing430, the oil flows in a direction inclined relative to the center line C1while the oil flows between the flow passage31B and the flow passage32B, particularly, while the oil flows through the second intermediate hole4354. In addition, a gap between an outer peripheral surface of the second part4522of the movable member452and an inner peripheral surface of the second hole4352is greater than the gap between the outer peripheral surface of the second part522of the movable member52of the first embodiment and the inner peripheral surface of the second hole352. For this reason, the resistance when the oil flows between the flow passage31B and the flow passage32B is reduced, as compared to the resistance in the first embodiment. As a result, the operation load when manually operating the arm9is reduced.

As described above, in the steering device400, the movable member452has the second part4522as an example of the first protrusion, which protrudes to have an outer diameter larger than the outer diameter of the first part521and is in contact with the seal member458, on a further downstream side than the first part521in the flow direction of the oil from the flow passage32B toward the flow passage31B. The movable member452also has the third part523as an example of the second protrusion, which protrudes to have an outer diameter larger than the outer diameter of the second part4522, on a further downstream side than the second part4522in the flow direction of the oil from the flow passage32B toward the flow passage31B. For this reason, according to the steering device400, since the oil is likely to flow in the direction inclined relative to the center line C1, the flow resistance is reduced, as compared to a configuration where the oil flows in a direction orthogonal to the center line C1and then flows in a direction parallel to the center line C1, so that the operation load when manually operating the arm9is reduced.

Further, the steering device400is provided with the second intermediate hole4354as an example of the truncated conical connection path formed concentrically with the flow passage32B on a further downstream side than the flow passage32B in the flow direction of the oil from the flow passage32B toward the flow passage31B and having an outer diameter that becomes larger in the flow direction. For this reason, according to the steering device400, since the oil is likely to flow in the direction inclined relative to the center line C1, the flow resistance is reduced, as compared to a configuration where the oil flows in a direction orthogonal to the center line C1and then flows in a direction parallel to the center line C1, so that the operation load when manually operating the arm9is reduced.

Fifth Embodiment

FIG. 10Adepicts an example of a schematic configuration of a second valve542in accordance with a fifth embodiment.FIG. 10Bdepicts an example of a schematic configuration of a manual valve543in accordance with the fourth embodiment.

A steering device500of the fifth embodiment is different from the steering device1of the first embodiment, in a second valve542and a manual valve543corresponding to the second valve42and the manual valve43. The second valve542and the manual valve543are different from the second valve42and the manual valve43of the first embodiment, in that the second valve542and the manual valve543are separate bodies. Hereinbelow, differences from the steering device1are described. The parts having the same functions between the steering device1and the steering device500are denoted with the same reference signs, and the detailed descriptions thereof are omitted.

Similarly to the first valve41described with reference toFIG. 6, the second valve542has the valve body61, the movable member62, the holding member63, the spring64, the cap65, and the seal member68. The second valve542is inserted in a through-hole37formed in the housing30. The through-hole37is formed in parallel to the through-hole35, and has a columnar first hole371formed on a front side and a columnar second hole372formed on a rear side and having a diameter larger than a diameter of the first hole371. The first hole371communicates with the flow passage32B, and the second hole372communicates with the flow passage31B.

The manual valve543has a cap570for plugging the through-hole35formed in the housing30, the handle57, and the annular seal member58for sealing a gap between the cap570and the housing30.

The cap570has a first part571corresponding to the first part521of the movable member52, and a second part572corresponding to the second part522of the movable member52. The cap570also has a first pillar-shaped part573corresponding to the first pillar-shaped part561of the cap55, and a second pillar-shaped part574corresponding to the second pillar-shaped part562of the cap55. The cap570also has a columnar third pillar-shaped part575having substantially the same diameter as an outer diameter of the second part572and a columnar fourth pillar-shaped part576having a diameter larger than the diameter of the third pillar-shaped part575between the second part572and the first pillar-shaped part573.

The first part571is formed with a through-hole577corresponding to the through-hole525of the movable member52. The fourth pillar-shaped part576is formed with a male screw578that is fastened to the female screw355formed in the through-hole35. An end portion on a rear side of the second pillar-shaped part574is formed with a female screw579, and the bolt59is fastened to the female screw579, so that the handle57is attached.

Also in the manual valve543configured as described above, when the male screw578is unfastened by the user and thus the seal member58does not seal the gap between the cap570and the housing30, the oil flows between the flow passage31B and the flow passage32B through the through-hole577formed in the first part571of the cap570. As a result, similarly to the manual valve43of the first embodiment, the operation load when manually operating the arm9is reduced.

Note that, the outer diameter of the first part571may be set small, like the outer diameter of the first part2521of the second embodiment. In this case, the through-hole577may not be provided.

Alternatively, the diameter of the first hole351of the through-hole35may be set large, like the diameter of the first hole3351of the third embodiment. In this case, the through-hole577may not be provided.

Alternatively, like the second part4522of the fourth embodiment, a cylindrical part having an outer diameter larger than the outer diameter of the first part571and smaller than the outer diameter of the second part572may be provided between the first part571and the second part572of the cap570. In addition, the through-hole35of the housing30may be formed to have a similar shape to the through-hole435of the housing430of the fourth embodiment.

Sixth Embodiment

FIG. 11depicts an example of a schematic configuration of a valve unit650in accordance with a sixth embodiment.

A steering device600of the sixth embodiment is different from the steering device1of the first embodiment, in a valve unit650corresponding to the valve unit50. The valve unit650is different from the valve unit50, in that a first valve641, a second valve642, and a manual valve643of the sixth embodiment are integrally provided. The parts having the same functions between the steering device1and the steering device600are denoted with the same reference signs, and the detailed descriptions thereof are omitted.

The valve unit650has the valve body51, the movable member52, the holding member53, the handle57, the seal member58, the valve body61, and the holding member63. The valve unit650also has a coil-shaped spring654for applying a spring force to the valve body51via the holding member53and applying the spring force to the valve body61via the holding member63, and a cap655for plugging a through-hole38formed in the housing30.

The through-hole38has a columnar first hole381formed on a front side, and a columnar second hole382formed behind the first hole381and having a diameter larger than a diameter of the first hole381. The through-hole38also has a columnar third hole383formed behind the second hole382and having a diameter larger than the diameter of the second hole382, and a columnar fourth hole384formed behind the third hole383and having a diameter larger than the diameter of the third hole383. The first hole381communicates with the flow passage32B. The second hole382communicates with the flow passage31B. The third hole383communicates with the flow passage32B. The fourth hole384communicates with the flow passage31B.

The cap655has a cylindrical first tubular part661provided on a front side, a cylindrical second tubular part662provided behind the first tubular part661, and a cylindrical third tubular part663provided behind the second tubular part662. The cap655also has a columnar first pillar-shaped part664provided behind the third tubular part663and a second pillar-shaped part665provided behind the first pillar-shaped part664.

The first tubular part661is similar to the tubular part551of the cap55and is formed with the through-hole553, and the movable member52is press-fitted therein.

An outer diameter of the second tubular part662is larger than an outer diameter of the first tubular part661. The second tubular part662is formed with a groove666recessed from an outer peripheral surface over an entire circumference. In the groove666, an O-ring667for sealing a space between an outer peripheral surface of the second tubular part662and an inner peripheral surface of the second hole382of the through-hole38is fitted.

An outer diameter of the third tubular part663is larger than the outer diameter of the second tubular part662. An outer peripheral surface of the third tubular part663is formed with a male screw668that is fastened to a female screw385formed in the through-hole38. In the third tubular part663, a seating surface669on which the valve body61is seated is formed. In the third tubular part663, a through-hole670that communicates an inside and the fourth hole384of the through-hole38located at an outside is formed in a direction of intersecting with the center line C1.

The first pillar-shaped part664is formed with a groove671recessed from an outer peripheral surface over an entire circumference. In the groove671, an O-ring672for sealing a space between an outer peripheral surface of the first pillar-shaped part664and an inner peripheral surface of the fourth hole384of the through-hole38is fitted.

The second pillar-shaped part665is similar to the second pillar-shaped part562of the cap55, and is formed with a female screw565to which the bolt59for attaching the handle57is fastened.

In the valve unit650configured as described above, the valve body61, the holding member63, the spring654, the cap655and the housing30constitute the first valve641. The valve body51, the movable member52, the holding member53, the spring654, the cap655, the seal member58and the housing30constitute the second valve642. The movable member52, the cap655, the handle57, the seal member58and the housing30constitute the manual valve643.

Also in the manual valve643configured as described above, when the male screw668is unfastened by the user and thus the seal member58does not seal the gap between the cap655and the housing30, the oil flows between the flow passage31B and the flow passage32B through the through-hole525formed in the first part521of the movable member52. As a result, similarly to the manual valve43of the first embodiment, the operation load when manually operating the arm9is reduced.

Note that, the outer diameter of the first part521of the movable member52may be set small, like the outer diameter of the first part2521of the second embodiment. In this case, the through-hole525may not be provided.

Alternatively, the diameter of the first hole381of the through-hole38may be set large, like the diameter of the first hole3351of the third embodiment. In this case, the through-hole525may not be provided.

Alternatively, like the second part4522of the fourth embodiment, a cylindrical part having an outer diameter larger than the outer diameter of the first part571and smaller than the outer diameter of the second part572may be provided between the first part521and the second part522of the movable member52. In addition, the through-hole38of the housing30may be formed to have a similar shape to the through-hole435of the housing430of the fourth embodiment.

According to the present invention, it is possible to reduce an operation load when manually changing the traveling direction of the ship body.