Lock valve and hydraulic steering system including same

Abstract

The disclosure relates generally to lock valves and hydraulic steering systems including a lock-valve apparatus comprising: a main body defining an internal space; a first check valve in the internal space of the main body; a second check valve in the internal space of the main body; and a spool body in the internal space of the main body between the first and second check valves, the spool body movable within and relative to the main body along a direction between the first and second check valves; wherein the main body defines, at least: a first fluid port in fluid communication with a first fluid chamber in the internal space of the main body between the first check valve and the spool body; a second fluid port in fluid communication with a second fluid chamber in the internal space of the main body between the second check valve and the spool body; a third fluid port in fluid communication with a space in the internal space of the main body on a side of the first check valve opposite the spool body; and a fourth fluid port in fluid communication with a space in the internal space of the main body on a side of the second check valve opposite the spool body, wherein the first check valve is configured to permit pressurized fluid to flow from the first fluid chamber to the space in the internal space of the main body on the side of the first check valve opposite the spool body, and to be opened in response to movement of the spool body relative to the main body along the direction and towards the first check valve; and wherein the second check valve is configured to permit pressurized fluid to flow from the second fluid chamber to the space in the internal space of the main body on the side of the second check valve opposite the spool body, and to be opened in response to movement of the spool body relative to the main body along the direction and towards the second check valve.

Description

[0001] LOCK VALVE AND HYDRAULIC STEERING SYSTEM INCLUDING SAME

[0002] CROSS-REFERENCE TO RELATED APPLICATION

[0003] This application claims the benefit of and priority from United States provisional patent application no. 63 / 587,016, filed September 29, 2023, the entire contents of which are incorporated by reference herein.

[0004] FIELD

[0005] This disclosure relates generally to lock valves and hydraulic steering systems including such lock valves.

[0006] SUMMARY

[0007] According to at least one embodiment, there is disclosed a lock-valve apparatus comprising: a main body defining an internal space; a first check valve in the internal space of the main body; a second check valve in the internal space of the main body; and a spool body in the internal space of the main body between the first and second check valves, the spool body movable within and relative to the main body along a direction between the first and second check valves. The main body defines, at least: a first fluid port in fluid communication with a first fluid chamber in the internal space of the main body between the first check valve and the spool body; a second fluid port in fluid communication with a second fluid chamber in the internal space of the main body between the second check valve and the spool body; a third fluid port in fluid communication with a space in the internal space of the main body on a side of the first check valve opposite the spool body; and a fourth fluid port in fluid communication with a space in the internal space of the main body on a side of the second check valve opposite the spool body. The first check valve is configured to permit pressurized fluid to flow from the first fluid chamber to the space in the internal space of the main body on the side of the first check valve opposite the spool body, and to be opened in response to movement of the spool body relative to the main body along the direction and towards the first check valve. The second check valve is configured to permit pressurized fluid to flow from the second fluid chamber to the space in the internal space of the main body on the side of the second check valve opposite the spool body, and to be opened in response to movement of the spool body relative to the main body along the direction and towards the second check valve.

[0008] In some embodiments, the spool body defines a groove recessed behind a maximum outer diameter of the spool body.

[0009] In some embodiments, the groove is in fluid communication with a fluid reservoir outside of the internal space of the main body.

[0010] In some embodiments, the main body further defines a first return port in fluid communication with the first port and positioned to be open to the groove when the spool body is at at least one position relative to the main body along the direction and closer to the first check valve than the second check valve.

[0011] In some embodiments, the first return port is off-center relative to the first port.

[0012] In some embodiments: the direction is along a longitudinal axis of the main body; the first port comprises a main conduit; at a plane parallel to the longitudinal axis, the main conduit of the first port becomes fully separated into, at least, (a) a conduit between the main conduit of the first port and the first fluid chamber, and (b) a conduit between the main conduit of the first port and the first return port; at the plane, the main conduit of the first port, the conduit between the main conduit of the first port and the first fluid chamber, and the conduit between the main conduit of the first port and the first return port extend over a range along the longitudinal axis; and along the longitudinal axis, the first return port is on a side of a midpoint of the range towards the second check valve from the midpoint.

[0013] In some embodiments, along the longitudinal axis, the first return port is more than 55% along the range in the direction towards the second check valve.

[0014] In some embodiments, along the longitudinal axis, the first return port is more than 60% along the range in the direction towards the second check valve.

[0015] In some embodiments, along the longitudinal axis, the first return port is more than 65% along the range in the direction towards the second check valve.

[0016] In some embodiments, along the longitudinal axis, the first return port is more than 70% along the range in the direction towards the second check valve.

[0017] In some embodiments, the main body further defines a second return port in fluid communication with the second port and positioned to be open to the groove when the spool body is at at least one position relative to the main body along the direction and closer to the second check valve than the first check valve.

[0018] In some embodiments, the second return port is off-center relative to the second port.

[0019] In some embodiments: the direction is along a longitudinal axis of the main body; the second port comprises a main conduit; at a plane parallel to the longitudinal axis, the main conduit of the second port becomes fully separated into, at least, (a) a conduit between the main conduit of the second port and the second fluid chamber, and (b) a conduit between the main conduit of the second port and the second return port; at the plane, the main conduit of the second port, the conduit between the main conduit of the second port and the second fluid chamber, and the conduit between the main conduit of the second port and the second return port extend over a range along the longitudinal axis; and along the longitudinal axis, the second return port is on a side of a midpoint of the range towards the first check valve from the midpoint.

[0020] In some embodiments, along the longitudinal axis, the second return port is more than 55% along the range in the direction towards the first check valve.

[0021] In some embodiments, along the longitudinal axis, the second return port is more than 60% along the range in the direction towards the first check valve.

[0022] In some embodiments, along the longitudinal axis, the second return port is more than 65% along the range in the direction towards the first check valve.

[0023] In some embodiments, along the longitudinal axis, the second return port is more than 70% along the range in the direction towards the first check valve.

[0024] In some embodiments, the first and second check valves each have a valve seat area and the spool body has a cross-sectional pilot area facing each of the first and second fluid chambers.

[0025] In some embodiments, a pilot ratio of the pilot area to the valve seat area is more than 4.1.

[0026] In some embodiments, a pilot ratio of the pilot area to the valve seat area is more than 4.5.

[0027] In some embodiments, a pilot ratio of the pilot area to the valve seat area is more than 5.0. In some embodiments, a pilot ratio of the pilot area to the valve seat area is more than

[0028] 5.5.

[0029] In some embodiments, a pilot ratio of the pilot area to the valve seat area is more than 6.0.

[0030] In some embodiments, a pilot ratio of the pilot area to the valve seat area is more than

[0031] 6.5.

[0032] In some embodiments, a pilot ratio of the pilot area to the valve seat area is more than 7.0.

[0033] In some embodiments, a pilot ratio of the pilot area to the valve seat area is more than

[0034] 7.5.

[0035] In some embodiments, a pilot ratio of the pilot area to the valve seat area is more than 8.0.

[0036] In some embodiments, a pilot ratio of the pilot area to the valve seat area is more than

[0037] 8.5.

[0038] In some embodiments, a pilot ratio of the pilot area to the valve seat area is more than 9.0.

[0039] In some embodiments, a pilot ratio of the pilot area to the valve seat area is more than

[0040] 9.5.

[0041] In some embodiments, a pilot ratio of the pilot area to the valve seat area is more than 10.0.

[0042] In some embodiments, a pilot ratio of the pilot area to the valve seat area is more than

[0043] 10.5.

[0044] In some embodiments, the first check valve comprises a valve body movable within a seat body.

[0045] In some embodiments, the seat body defines a seal edge and the valve body is sealable against the seal edge during operation of the first check valve.

[0046] In some embodiments, the seat body is integrally formed.

[0047] In some embodiments, the seat body comprises a valve-body-guiding portion positioned to guide the valve body during substantially all or all of movement of the valve body during operation of the first check valve. In some embodiments, the first check valve further comprises a guide body movable within the seat body and contacting the valve body.

[0048] In some embodiments, the valve-body-guiding portion is positioned to contact the guide body and limit movement of the guide body transverse to the longitudinal axis during substantially all or all of movement of the valve body during operation of the first check valve.

[0049] In some embodiments, when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.015 inches.

[0050] In some embodiments, when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.014 inches.

[0051] In some embodiments, when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.013 inches.

[0052] In some embodiments, when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.012 inches.

[0053] In some embodiments, when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.011 inches.

[0054] In some embodiments, the guide body defines a fluid passage open to opposite sides of the guide body along the longitudinal axis.

[0055] In some embodiments, the second check valve comprises a valve body movable within a seat body.

[0056] In some embodiments, the seat body defines a seal edge and the valve body is sealable against the seal edge during operation of the second check valve.

[0057] In some embodiments, the seat body is integrally formed.

[0058] In some embodiments, the seat body comprises a valve-body-guiding portion positioned to guide the valve body during substantially all or all of movement of the valve body during operation of the second check valve. In some embodiments, the second check valve further comprises a guide body movable within the seat body and contacting the valve body.

[0059] In some embodiments, the valve-body-guiding portion is positioned to contact the guide body and limit movement of the guide body transverse to the longitudinal axis during substantially all or all of movement of the valve body during operation of the second check valve.

[0060] In some embodiments, when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.015 inches.

[0061] In some embodiments, when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.014 inches.

[0062] In some embodiments, when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.013 inches.

[0063] In some embodiments, when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.012 inches.

[0064] In some embodiments, when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.011 inches.

[0065] In some embodiments, the guide body defines a fluid passage open to opposite sides of the guide body along the longitudinal axis.

[0066] A hydraulic steering system comprising the lock-valve apparatus and a hydraulic pump operable to pump hydraulic fluid into and out of the first and second fluid ports.

[0067] In some embodiments, the system further comprises a double-acting hydraulic cylinder comprising a first side fluidly connected to the third port and a second side fluidly connected to the fourth port. According to at least one embodiment, there is disclosed a hydraulic steering system comprising the lock-valve apparatus and a double-acting hydraulic cylinder comprising a first side fluidly connected to the third port and a second side fluidly connected to the fourth port.

[0068] According to at least one embodiment, there is disclosed a watercraft comprising the hydraulic steering system and a steering device operable to move relative to a hull, transom, or other structure of the watercraft in response to movement of the double-acting hydraulic cylinder.

[0069] Other aspects and features will become apparent to those ordinarily skilled in the art upon review of the following description of illustrative embodiments in conjunction with the accompanying figures.

[0070] BRIEF DESCRIPTION OF THE DRAWINGS

[0071] FIG. 1 schematically illustrates a hydraulic steering system according to one embodiment.

[0072] FIG. 2 is a cross-sectional view of a lock valve of the system of FIG. 1.

[0073] FIG. 3 is a perspective view of a ball-seat body of the lock valve of FIG. 2.

[0074] FIG. 4 is a cross-sectional view of a ball-guide body of the lock valve of FIG. 2.

[0075] FIG. 5 is a perspective view of a ballplug-cage body of the lock valve of FIG. 2.

[0076] FIG. 6 is a perspective view of a pump apparatus according to one embodiment and including the lock valve of FIG. 2.

[0077] FIG. 7 is a cross-sectional view of the pump apparatus of FIG. 6.

[0078] FIG. 8 is a perspective view of a pump apparatus according to another embodiment.

[0079] DETAILED DESCRIPTION

[0080] In FIG. 1 , a hydraulic steering system according to one embodiment is shown generally at 10.

[0081] Rotary Pump

[0082] The hydraulic steering system 10 includes a rotary pump 11. The pump 11 may, in some embodiments, be a swash-plate pump, a piston pump, a positive-displacement pump, or another rotary pump. The pump 11 may be rotated by rotation of a steering wheel 13. The pump 11 is of the two-port type, having ports 15 and 17 that may be intake ports or discharge ports for hydraulic fluid depending upon a direction in which the steering wheel 13 is turned relative to the pump 11. For example, if the steering wheel 13 is rotated clockwise relative to the pump 11, then the pump 11 may pump hydraulic fluid out of the port 17 and the port 17 may act as a discharge port, and the port 15 may act as an intake port receiving a return flow of hydraulic fluid. Likewise, if the steering wheel 13 is rotated counter-clockwise relative to the pump 11, then the pump 11 may pump hydraulic fluid out of the port 15 and the port 15 may act as a discharge port, and the port 17 may act as an intake port receiving a return flow of hydraulic fluid.

[0083] Alternative embodiments may differ. For example, the steering wheel 13 is an example only, and the pump 11 may be rotated in other ways, for example by a lever, a handle, or another steering input device. Also, alternative embodiments may include one or more alternatives to the pump 11, or the pump 11 may differ in alternative embodiments.

[0084] Lock Valve

[0085] The hydraulic steering system 10 also includes a lock valve 18 including a first port 21, a second port 22, a third port 23, and a fourth port 24. A hydraulic line 7 connects the port 15 of the pump 11 to the port 21 of the lock valve 18, and a hydraulic line 8 connects the port 17 of the pump 11 to the port 22 of the lock valve 18. However, in alternative embodiments, as shown in FIG. 7 for example, a pump apparatus 26 includes the pump 11 and the lock valve 18 without requiring such hydraulic lines. Still other alternative embodiments may differ.

[0086] Referring to FIG. 2, the lock valve 18 includes a main body 106 having an internal surface 107 defining an internal space shown generally at 108. In the embodiment shown, the internal space 108 is generally rotationally symmetric about a longitudinal axis 110 of the main body 106 and includes end portions shown generally at 111 and 112 and a central portion shown generally at 113 and between the end portions 111 and 112. The internal surface 107 defines threads in the end portion 111 and includes a stop portion 114 between the end portion 111 and the central portion 113 and surrounding the central portion 113. The internal surface 107 defines threads in the end portion 111 and includes a stop portion 115 between the end portion 111 and the central portion 113 and surrounding the central portion 113. Alternative embodiments may differ. For example, alternative embodiments may not necessarily be rotationally symmetric and may include one or more alternatives to threads.

[0087] Also, references herein to “end portions” are not intended to imply that a structure must end at such end portions. For example, some embodiments may include structure that extends past such end portions.

[0088] Lock Valve End Portions

[0089] The lock valve 18 also includes a ball-seat body 116 shown in FIGS. 2 and 3 and that may be positioned in the end portion 111. The ball-seat body 116 is generally rotationally symmetric about the longitudinal axis 110 when the ball-seat body 116 is positioned in the end portion 111 as shown in FIG. 2 and has an end face 117, an outer portion of which is positionable against the stop portion 114 when the ball-seat body 116 is positioned in the end portion 111 with a gasket, O-ring, or other seal 121 between the ball-seat body 116 and the internal surface 107 as shown in FIG. 2.

[0090] The ball-seat body 116 defines an opening shown generally at 118 in the end face 117. The ball-seat body 116 includes a ball-guiding portion (or valve-body-guiding portion) 159, and the opening 118 is open to an internal space shown generally at 119 and defined by an inner surface 160 in the ball-guiding portion 159. The internal space 119 is generally rotationally symmetric about the longitudinal axis 110 when the ball-seat body 116 is positioned in the end portion 111 as shown in FIG. 2. Also, the internal space 119 has a diameter 129 greater than the opening 118 to define a ball-seal edge 120 where the opening 118 meets the internal space 119. A ball 122 has a diameter less than the diameter of the internal space 119 and greater than the diameter of the ball-seal edge 120 so that the ball 122 is sealable against the ball-seal edge 120, and the ball 122 may function as part of a check valve including the ball 122.

[0091] The ball-seat body 116 also includes stop projections 125, 126, 127, and 128 surrounding the opening 118 and projecting away from the end face 117 in a direction away from the opening 118 and from the internal space 119.

[0092] The ball-seat body 116 also defines transverse openings shown generally at 123 and 124 and open to the internal space 119. In the embodiment shown, the ball-guiding portion 159 and the portion having the ballseal edge 120 are integrally formed as a single ball-seat body 116, which may in some embodiments allow for more-precise relative positions of the inner surface 160 and the ballseal edge 120.

[0093] The lock valve 18 also includes a ball-guide body 131 shown in FIGS. 2 and 4 and that is sized to be positioned within the internal space 119 and is generally rotationally symmetric about the longitudinal axis 110 when the ball-guide body 131 is positioned in the end portion 111 as shown in FIG. 2.

[0094] The ball-guide body 131 defines a ball-seat region shown generally at 133 and sized and positioned to receive a portion of the ball 122 when the ball-guide body 131 is positioned in the end portion 111 as shown in FIG. 2. The ball 122 and the ball-guide body 131 typically move together and do not separate from each other in operation.

[0095] In the embodiment shown, the ball-guiding portion 159 and the inner surface 160 are positioned to guide the ball-seat body 116 and the ball 122 by being positioned to contact the ball-seat body 116, the ball 122, or both and limit movement of the ball-seat body 116 and the ball 122 transverse to the longitudinal axis 110 during substantially all or all of movement of the ball 122 during operation of the ball 122 during as part of a check valve.

[0096] The ball-guide body 131 also defines a fluid passage shown generally at 134 and open to both the ball-seat region 133 and an end of the ball-guide body 131 shown generally at 135 opposite the ball-seat region 133 along the longitudinal axis 110 when the ball-guide body 131 is positioned in the end portion 111 as shown in FIG. 2. The fluid passage 134 may therefore permit fluid flow between the ball-seat region 133 and a space opposite the ball-seat region 133 along the longitudinal axis 110 and within the end portion 111 when the ball-guide body 131 is positioned in the end portion 111 as shown in FIG. 2. Sometimes, during assembly, the ball 122 or other components may be inadvertently omitted, and the fluid passage 134 would ensure that if the ball 122 or other components are omitted, then the lock valve 18 would fail testing such as end-of-line testing.

[0097] The lock valve 18 also includes a plug-cage body 136 shown in FIGS. 2 and 5. The plug-cage body 136 is generally rotationally symmetric about the longitudinal axis 110 when the plug-cage body 136 is positioned in the end portion 111 as shown in FIG. 2 and that may be positioned in the end portion 111 and retained in the end portion 111 by threaded engagement between the threads defined by the internal surface 107 in the end portion 111 and threads of the plug-cage body 136, with a gasket, O-ring, or other seal 137 between the plugcage body 136 and the internal surface 107 as shown in FIG. 2.

[0098] The plug-cage body 136 defines an internal space shown generally at 139 and sized to receive the ball-seat body 116 as shown in FIG. 2. The plug-cage body 136 also defines transverse openings such as the shown transverse openings generally at 138 and open to the internal space 139. The transverse openings 123 and 124 permit fluid flow between the internal space 119 and the internal space 139, and the transverse openings (such as the transverse opening 138) of the plug-cage body 136 permit fluid flow between the internal space 139 and a space shown generally at 130 that is laterally external to the plug-cage body 136 and within the end portion 111.

[0099] The plug-cage body 136 also defines an end surface 140 facing into the internal space 139, and a coil spring 141 may be positioned and compressed between the end surface 140 and the ball-guide body 131 to urge the ball 122 resiliently against the ball-seal edge 120. The coil spring 141 exerts sufficient force on the ball 122 such that, unless a force is applied to the ball 122 to separate the ball 122 from the ball-seal edge 120, the ball 122 seals the opening 118 to prevent fluid flow through the opening 118.

[0100] Alternative embodiments may differ. For example, alternative embodiments may include one or more alternatives to the ball-seat body 116, to the ball-guide body 131, to the plug-cage body 136, or to any two or all three thereof, and such alternatives may have different shapes and may not necessarily be rotationally symmetric. Also, alternative embodiments may include one or more alternatives to the check valve including the ball 122, such as a poppet valve for example. In general, the ball 122, a poppet, or another different valve body may be referred to generally as a valve body.

[0101] The end portion 112 may include similar components to the end portion 111, but reversed as shown in FIG. 2, and the end portion 112 includes a space shown generally at 156 and similar to the space 130 and a ball 165 similar to the ball 122. The ball 165 may function as part of a check valve including the ball 165. Ball-Guide Body Diameter

[0102] The ball-guide body 131 has a maximum diameter 132 that is less than the diameter 129. In the embodiment shown, the maximum diameter 132 is about 0.237 inches, and the diameter 129 is about 0.257 inches. As a result, when the ball-guide body 131 is centered within the internal space 119, the minimum clearance between the ball-guide body 131 and a surface defining the internal space 119 is about 0.010 inches. In various embodiments, that minimum clearance may be less than 0.015 inches, less than 0.014 inches, less than 0.013 inches, less than 0.012 inches, or less than 0.011 inches.

[0103] Also, in the embodiment shown maximum diameter 132 is greater than a diameter of the ball 122.

[0104] However, alternative embodiments may differ and may not necessarily be rotationally symmetric but may for example have noncircular cross-sections.

[0105] Lock Valve Spool Body

[0106] The lock valve 18 also includes a spool body (or lockspool) 142 in the internal space 108 as shown in FIG. 2. The spool body 142 is generally rotationally symmetric about the longitudinal axis 110 when the spool body 142 is positioned in the end portion 111 as shown in FIG. 2.

[0107] The spool body 142 includes a central portion 143 in the central portion 113 and having a maximum outer diameter that is close to an inner diameter of the central portion 113 to allow the spool body 142 to slide within the central portion 113 and along the longitudinal axis 110 while preventing fluid flow between the central portion 113 and the internal surface 107 and between sides shown generally at 144 and 145 of the spool body 142 that are opposite sides along the longitudinal axis 110 of the spool body 142.

[0108] The spool body 142 defines a groove shown generally at 152 in an outer surface of the central portion 113 around the longitudinal axis 110 and recessed behind the maximum outer diameter of the central portion 143. The groove 152 is centered in the central portion 113 along the longitudinal axis 110 has a longitudinal width 153 along the longitudinal axis 110.

[0109] The spool body 142 also defines an end surface 146 of the central portion 113 on the side 145, and end surface 147 of the central portion 113 on the side 144. On the side 145, a stop projection 148 projects away from the end surface 146 and away from the central portion 113 and is surrounded by the end surface 146. On the side 144, a stop projection 149 projects away from the end surface 147 and away from the central portion 113 and is surrounded by the end surface 147. On the side 145, a valve-opening projection 150 projects away from the stop projection 148 and is surrounded by an end surface 154 of the stop projection 148. On the side 144, a valve-opening projection 151 projects away from the stop projection 149 and is surrounded by an end surface 155 of the stop projection 149.

[0110] The valve-opening projection 150 is sized and positioned to extend through the opening 118, and the valve-opening proj ection 151 is sized and positioned to extend through a similar opening in the end portion 112. Also, the end surface 154 is positioned to abut the stop projections 125, 126, 127, and 128 when the spool body 142 slides in the internal space 108 in a direction towards the end portion 111, and the end surface 155 is positioned to abut similar stop projections of the end portion 112 when the spool body 142 slides in the internal space 108 in a direction towards the end portion 112.

[0111] Alternative embodiments may differ. For example, alternative embodiments may not necessarily be rotationally symmetric or may have different shapes.

[0112] Pilot Ratio

[0113] The ball-seal edge 120 surrounds an area that may be referred to as a seat area, and the cross-sectional area of the spool body 142 facing the end portion 111 may be referred to as a pilot area. The ratio of the pilot area to the seat area may be referred to as a pilot ratio.

[0114] For example, in the embodiment shown, the pilot ratio is about 10.87. In various embodiments, the pilot ratio may be more than 4.1, more than 4.5, more than 5.0, more than 5.5, more than 6.0, more than 6.5, more than 7.0, more than 7.5, more than 8.0, more than 8.5, more than 9.0, more than 9.5, more than 10.0, or more than 10.5.

[0115] Lock Valve Fluid Conduits

[0116] A fluid chamber shown generally at 36 is in the central portion 113 between the side 145 of the spool body 142 and the ball-seat body 116. As indicated above, the coil spring 141 exerts sufficient force on the ball 122 such that, unless a force is applied to the ball 122 to separate the ball 122 from the ball-seal edge 120, the ball 122 seals the opening 118 to prevent fluid flow through the opening 118. Therefore, the unless a force is applied to the ball 122 to separate the ball 122 from the ball-seal edge 120, the ball 122 seals the fluid chamber 36 from the internal spaces 119 and 139 and from the space 130. The port 21 is in fluid communication with the hydraulic line 7 as described above, and is also is in fluid communication with the fluid chamber 36.

[0117] Likewise, a fluid chamber shown generally at 38 is in the central portion 113 between the side 144 of the spool body 142 and a ball-seat body similar to the ball-seat body 116 at the end portion 112. As with the ball 122, unless a force is applied to the ball 165 to separate the ball 165 from a ball-seal edge of the end portion 112, the ball 165 seals the fluid chamber 38 from the space 156. The port 22 is in fluid communication with the hydraulic line 8 as described above, and is also is in fluid communication with the fluid chamber 38.

[0118] The port 23 (also shown in FIG. 1) is in fluid communication with the space 130 and the internal spaces 119 and 139, and the port 24 (also shown in FIG. 1) is in fluid communication with the space 156.

[0119] Fluid Return Ports

[0120] The port 21 is also in fluid communication with a return port 157 extending through the internal surface 107 and facing the central portion 113, and the port 22 is also in fluid communication with a return port 158 extending through the internal surface 107 and facing the central portion 113. The return ports 157 and 158 are positioned such that, when the spool body 142 slides in the internal space 108 in a direction towards the end portion 111, the port return 158 is open to the groove 152, when the spool body 142 slides in the internal space 108 in a direction towards the end portion 112, the return port 157 is open to the groove 152, and otherwise (including when the spool body 142 is centered between the end portions 111 and 112) the return ports 157 and 158 face and are sealed by an outer surface of the central portion 143.

[0121] The spool body 142 includes a fluid conduit positioned to communicate fluid from the groove 152 to a fluid reservoir of a pump apparatus or more generally a fluid reservoir outside of the internal space 108, such as the fluid reservoir 174 described below for example. The port 21 includes a main conduit 166. At a plane 169 parallel to the longitudinal axis 110, the main conduit 166 becomes fully separated into: a conduit 167 between the main conduit 166 and the fluid chamber 36; and a conduit 168 between the main conduit 166 and the return port 157. At the plane 169, the main conduit 166 and the conduits 167 and 168 extend over a range 170 along the longitudinal axis 110. Along the longitudinal axis 110, the return port 157 is on a side of a midpoint 171 of the range 170 towards the return port 158 (or towards the check valve of the ball 165) from the midpoint 171. In various embodiments, along the longitudinal axis 110, the return port 157 may be more than 50% along the range 170 in a direction towards the return port 158, more than 55% along the range 170 in the direction towards the return port 158, more than 60% along the range 170 in the direction towards the return port 158, more than 65% along the range 170 in the direction towards the return port 158, or more than 70% along the range 170 in the direction towards the return port 158.

[0122] In other words, the return port 157 is off-center relative to the port 21.

[0123] Likewise, the return port 158 is off-center relative to the port 22 as described above but in a direction towards the return port 157. In other words, a plane parallel to the longitudinal axis 110, a main conduit of the port 22 becomes fully separated into a conduit between the main conduit 166 and the fluid chamber 38 and a conduit between the main conduit 166 and the return port 158, at that plane 169, the main conduit and the other conduits extend over a range along the longitudinal axis 110, and along the longitudinal axis 110, the return port 158 may be more than 50% along the range in a direction towards the return port 157, more than 55% along the range in the direction towards the return port 157, more than 60% along the range in the direction towards the return port 157, more than 65% along the range in the direction towards the return port 157, or more than 70% along the range in the direction towards the return port 157.

[0124] Pump Apparatus

[0125] Although shown schematically in FIG. 1 as two separate parts, the pump 11 and the lock valve 18 may in one embodiment be combined in a single pump apparatus, such as the pump apparatus shown generally at 26 in FIGS. 6 and 7. The pump apparatus 26 includes the pump 11 and the lock valve 18 within a housing of the pump apparatus 26. In the embodiment shown, the pump 11 is a piston pump including pistons 172 and 173, although alternative embodiments may differ. The pump apparatus 26 also defines a fluid reservoir 174 for storing hydraulic fluid for use as described herein, for example.

[0126] The pump apparatus 26 also includes a steering shaft 161 connectable to the steering wheel 13 and operable to cause the pump 11 to pump hydraulic fluid in response to rotation of the steering wheel 13 around a longitudinal axis of rotation 162 of the steering shaft 161.

[0127] In another embodiment, the pump 11 and the lock valve 18 may be combined in the pump apparatus shown generally at 27 in FIG. 8. The pump apparatus 27 is similar to the pump apparatus 26 but has a differently shaped housing.

[0128] Alternative embodiments may differ.

[0129] Hydraulic Cylinder and Steering Device

[0130] Referring back to FIG. 1, a hydraulic line 12 connects the port 23 to a first side of a double-acting hydraulic cylinder 16, and a hydraulic line 14 connects the port 24 to a second side opposite the first side of the double-acting hydraulic cylinder 16. Hydraulic fluid leaving the port 23 and hydraulic fluid entering the port 24 cause a piston 163 of the double-acting hydraulic cylinder 16 to move relative to a housing 164 of the double-acting hydraulic cylinder 16 towards the second side of the double-acting hydraulic cylinder 16. Hydraulic fluid leaving the port 24 and hydraulic fluid entering the port 23 cause the piston 163 to move relative to the housing 164 towards the first side of the double-acting hydraulic cylinder 16.

[0131] The piston 163 may be coupled to a steering device 19, which may be an inboard motor of a watercraft, an outboard motor of a watercraft, a rudder of a watercraft, or another steering device. In some embodiments, such a watercraft may be a boat, an aquatic vessel, or a marine vessel, for example, and movement of the piston 163 relative to the housing 164 may move such the steering device 19 relative to a hull, transom, or other structure of such a watercraft such that hydraulic fluid entering or leaving the port 23 and hydraulic fluid entering or leaving the port 24 may steer such a watercraft. Operation

[0132] Referring to FIGS. 1 and 3, when the steering wheel 13 is released, and therefore no pressurized fluid is pumped by the pump 11 towards or away from the port 21 or 22, the spool body 142 is approximately centered with a gap between the valve-opening projection 150 and the ball 122 approximately equal to a gap between the valve-opening projection 151 and the ball 165. With the spool body 142 in this position, the balls seal their respective valves, and the return ports 157 and 158 are sealed by the outer surface of the central portion 143, thereby preventing flow of hydraulic fluid through any of the ports 21, 22, 23, and 24. As a result, when the steering wheel 13 is released, the lock valve 18 prevents movement of the piston 163 relative to the housing 164 and prevents movement of the steering device 19 relative to a hull, transom, or other structure of a watercraft.

[0133] However, when the steering wheel 13 is turned, pressurized fluid is pumped from the pump 11, for example out of the port 15, which provides pressurized fluid at the port 21 and in the fluid chamber 36. Pressurized fluid in the fluid chamber 36 unseats the ball 122, allowing fluid to flow from the port 21 to the port 23, and pressurized fluid in the fluid chamber 36 also causes the spool body 142 to move towards the end portion 112 such that the valve-opening projection 151 contacts and unseats the ball 165, permitting return flow of fluid into the port 24 and to the port 22 through the space 156. The check valve including the ball 122 is therefore configured to be opened in response to movement of the spool body 142 towards the end portion 112. As a result, fluid flow into the port 21 and to the port 23, and fluid flow into the port 24 and to the port 22, allows rotation of the steering wheel 13 to move the piston 163 relative to the housing 164, which causes the steering device 19 to move relative to a hull, transom, or other structure of a watercraft to steer the watercraft.

[0134] In some circumstances and at some times, a rate of flow of fluid passing through the port 21 in one direction may differ from a rate of flow of fluid passing through the port 22 in an opposite direction. Such a difference may result from unbalanced cylinders in the pump 11 or from expansion or contraction of hoses or other components that may expend or contract in response to changes in fluid pressure. Such a difference may cause fluid to flow out of the return port 158 and to a fluid reservoir, such as the fluid reservoir 174 described below for example. When the steering wheel 13 is turned in the opposite direction, pressurized fluid is pumped from the pump 11 out of the port 17 instead of out of the port 15, and the process as described above takes place in the opposite way.

[0135] As a result, the lock valve 18 can prevent the steering device 19 from moving relative to a hull, transom, or other structure of a watercraft without movement of the steering wheel 13, but the lock valve 18 allows the steering wheel 13 to move steering device 19 from moving relative to a hull, transom, or other structure of a watercraft to steer the watercraft by movement of the steering wheel 13.

[0136] Back-Pressure

[0137] A load on the steering device 19 may be caused by water currents or other forces on the steering device 19, and such a load may cause fluid back-pressure in the space 130 or in the space 156, depending on a direction of the load. When the steering wheel 13 is turned in a direction that causes the steering device 19 to move in the same direction as the load, then such back-pressure in the space 130 tends to close the valve of the ball 122, or such backpressure in the space 156 tends to close the valve of the ball 165. Such tendency to close valves can cause discontinuous steering in a direction that causes the steering device 19 to move in the same direction as the load.

[0138] For example, if the steering wheel 13 is turned in a direction such that pressurized fluid is pumped from the pump 11 and out of the port 15, turning the steering wheel 13 in that direction causes fluid to out of the port 23. A load on the steering device 19 in the same direction causes fluid pressure in the port 24. Such fluid pressure in the port 24 tends to urge the ball 165 against the ball-seal edge of the end portion 112, restricting return flow of fluid into the port 24 and to the port 22 through the space 156 and therefore limiting fluid flow out of the port 23.

[0139] When compared to other local valves, the pilot ratio of the embodiment shown may be relatively high. Such a relatively high pilot ratio may increase force exerted by fluid on the spool body 142 relative to force exerted on a ball. For example, if the steering wheel 13 is turned in a direction such that pressurized fluid is pumped from the pump 11 and out of the port 15, a relatively high pilot ratio increases force on the spool body 142 from fluid in the fluid chamber 36 relative to force on the ball from fluid pressure in the port 24, increasing the tendency of the spool body 142 to keep the ball 165 unseated from the ball-seal edge of the end portion 112 and avoiding the tendency to restrict return flow of fluid into the port 24 and to the port 22 through the space 156.

[0140] However, in general, such a relatively high pilot ratio increases cross-sectional areas of the fluid chambers 36 and 38, and increased cross-sectional areas of the fluid chambers 36 and 38 can lead to increased volumes of the fluid chambers 36 and 38 if other dimensions of the lock valve 18 are the same. Increased volumes of the fluid chambers 36 and 38 can increase deadband, which represents amounts by which the steering wheel 13 must be turned only to move the spool body 142 and not to move the steering device 19 relative to a hull, transom, or other structure of a watercraft.

[0141] Such deadband can be reduced by reducing a stroke length or distance along the longitudinal axis 110 that the spool body 142 must move between a position that unseats the ball 122 from the ball-seal edge 120 and a position that unseats the ball 165 from the ball-seal edge of the end portion 112. Off-center return ports 157 and 158, as described above, may facilitate such a reduced stroke length.

[0142] Summary

[0143] Although specific embodiments have been described and illustrated, such embodiments should be considered illustrative only and not as limiting the invention as construed according to the accompanying claims.

Claims

CLAIMS1. A lock-valve apparatus comprising: a main body defining an internal space; a first check valve in the internal space of the main body; a second check valve in the internal space of the main body; and a spool body in the internal space of the main body between the first and second check valves, the spool body movable within and relative to the main body along a direction between the first and second check valves; wherein the main body defines, at least: a first fluid port in fluid communication with a first fluid chamber in the internal space of the main body between the first check valve and the spool body; a second fluid port in fluid communication with a second fluid chamber in the internal space of the main body between the second check valve and the spool body; a third fluid port in fluid communication with a space in the internal space of the main body on a side of the first check valve opposite the spool body; and a fourth fluid port in fluid communication with a space in the internal space of the main body on a side of the second check valve opposite the spool body; wherein the first check valve is configured to permit pressurized fluid to flow from the first fluid chamber to the space in the internal space of the main body on the side of the first check valve opposite the spool body, and to be opened in response to movement of the spool body relative to the main body along the direction and towards the first check valve; and wherein the second check valve is configured to permit pressurized fluid to flow from the second fluid chamber to the space in the internal space of the main body on the side of the second check valve opposite the spool body, and to be opened in response to movement of the spool body relative to the main body along the direction and towards the second check valve.

2. The apparatus of claim 1 wherein the spool body defines a groove recessed behind a maximum outer diameter of the spool body.

3. The apparatus of claim 2 wherein the groove is in fluid communication with a fluid reservoir outside of the internal space of the main body.

4. The apparatus of claim 2 or 3 wherein the main body further defines a first return port in fluid communication with the first port and positioned to be open to the groove when the spool body is at at least one position relative to the main body along the direction and closer to the first check valve than the second check valve.

5. The apparatus of claim 4 wherein the first return port is off-center relative to the first port.

6. The apparatus of claim 4 wherein: the direction is along a longitudinal axis of the main body; the first port comprises a main conduit; at a plane parallel to the longitudinal axis, the main conduit of the first port becomes fully separated into, at least,(a) a conduit between the main conduit of the first port and the first fluid chamber, and(b) a conduit between the main conduit of the first port and the first return port; at the plane, the main conduit of the first port, the conduit between the main conduit of the first port and the first fluid chamber, and the conduit between the main conduit of the first port and the first return port extend over a range along the longitudinal axis; and along the longitudinal axis, the first return port is on a side of a midpoint of the range towards the second check valve from the midpoint.

7. The apparatus of claim 6 wherein, along the longitudinal axis, the first return port is more than 55% along the range in the direction towards the second check valve.

8. The apparatus of claim 6 wherein, along the longitudinal axis, the first return port is more than 60% along the range in the direction towards the second check valve.

9. The apparatus of claim 6 wherein, along the longitudinal axis, the first return port is more than 65% along the range in the direction towards the second check valve.

10. The apparatus of claim 6 wherein, along the longitudinal axis, the first return port is more than 70% along the range in the direction towards the second check valve.

11. The apparatus of any one of claims 2 to 10 wherein the main body further defines a second return port in fluid communication with the second port and positioned to be open to the groove when the spool body is at at least one position relative to the main body along the direction and closer to the second check valve than the first check valve.

12. The apparatus of claim 11 wherein the second return port is off-center relative to the second port.

13. The apparatus of claim 11 wherein: the direction is along a longitudinal axis of the main body; the second port comprises a main conduit; at a plane parallel to the longitudinal axis, the main conduit of the second port becomes fully separated into, at least,(a) a conduit between the main conduit of the second port and the second fluid chamber, and(b) a conduit between the main conduit of the second port and the second return port; at the plane, the main conduit of the second port, the conduit between the main conduit of the second port and the second fluid chamber, and the conduit between the main conduit of the second port and the second return port extend over a range along the longitudinal axis; and along the longitudinal axis, the second return port is on a side of a midpoint of the range towards the first check valve from the midpoint.

14. The apparatus of claim 13 wherein, along the longitudinal axis, the second return port is more than 55% along the range in the direction towards the first check valve.

15. The apparatus of claim 13 wherein, along the longitudinal axis, the second return port is more than 60% along the range in the direction towards the first check valve.

16. The apparatus of claim 13 wherein, along the longitudinal axis, the second return port is more than 65% along the range in the direction towards the first check valve.

17. The apparatus of claim 13 wherein, along the longitudinal axis, the second return port is more than 70% along the range in the direction towards the first check valve.

18. The apparatus of any one of claims 1 to 17 wherein the first and second check valves each have a valve seat area and the spool body has a cross-sectional pilot area facing each of the first and second fluid chambers.

19. The apparatus of claim 18 wherein a pilot ratio of the pilot area to the valve seat area is more than 4.1.

20. The apparatus of claim 18 wherein a pilot ratio of the pilot area to the valve seat area is more than 4.5.

21. The apparatus of claim 18 wherein a pilot ratio of the pilot area to the valve seat area is more than 5.0.

22. The apparatus of claim 18 wherein a pilot ratio of the pilot area to the valve seat area is more than 5.5.

23. The apparatus of claim 18 wherein a pilot ratio of the pilot area to the valve seat area is more than 6.0.

24. The apparatus of claim 18 wherein a pilot ratio of the pilot area to the valve seat area is more than 6.5.

25. The apparatus of claim 18 wherein a pilot ratio of the pilot area to the valve seat area is more than 7.0.

26. The apparatus of claim 18 wherein a pilot ratio of the pilot area to the valve seat area is more than 7.5.

27. The apparatus of claim 18 wherein a pilot ratio of the pilot area to the valve seat area is more than 8.0.

28. The apparatus of claim 18 wherein a pilot ratio of the pilot area to the valve seat area is more than 8.5.

29. The apparatus of claim 18 wherein a pilot ratio of the pilot area to the valve seat area is more than 9.0.

30. The apparatus of claim 18 wherein a pilot ratio of the pilot area to the valve seat area is more than 9.5.

31. The apparatus of claim 18 wherein a pilot ratio of the pilot area to the valve seat area is more than 10.0.

32. The apparatus of claim 18 wherein a pilot ratio of the pilot area to the valve seat area is more than 10.5.

33. The apparatus of any one of claims 1 to 32 wherein the first check valve comprises a valve body movable within a seat body.

34. The apparatus of claim 33 wherein the seat body defines a seal edge and the valve body is sealable against the seal edge during operation of the first check valve.

35. The apparatus of claim 34 wherein the seat body is integrally formed.

36. The apparatus of claim 33, 34, or 35 wherein the seat body comprises a valve-body- guiding portion positioned to guide the valve body during substantially all or all of movement of the valve body during operation of the first check valve.

37. The apparatus of any one of claims 33 to 36 wherein the first check valve further comprises a guide body movable within the seat body and contacting the valve body.

38. The apparatus of claim 37, when dependent from claim 36, wherein the valve-body - guiding portion is positioned to contact the guide body and limit movement of the guide body transverse to the longitudinal axis during substantially all or all of movement of the valve body during operation of the first check valve.

39. The apparatus of claim 37, when dependent from claim 36, or of claim 38, wherein when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.015 inches.

40. The apparatus of claim 37, when dependent from claim 36, or of claim 38, wherein when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.014 inches.

41. The apparatus of claim 37, when dependent from claim 36, or of claim 38, wherein when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.013 inches.

42. The apparatus of claim 37, when dependent from claim 36, or of claim 38, wherein when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.012 inches.

43. The apparatus of claim 37, when dependent from claim 36, or of claim 38, wherein when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.011 inches.

44. The apparatus of any one of claims 37 to 43 wherein the guide body defines a fluid passage open to opposite sides of the guide body along the longitudinal axis.

45. The apparatus of any one of claims 1 to 44 wherein the second check valve comprises a valve body movable within a seat body.

46. The apparatus of claim 45 wherein the seat body defines a seal edge and the valve body is sealable against the seal edge during operation of the second check valve.

47. The apparatus of claim 46 wherein the seat body is integrally formed.

48. The apparatus of claim 44, 46, or 47 wherein the seat body comprises a valve-body - guiding portion positioned to guide the valve body during substantially all or all of movement of the valve body during operation of the second check valve.

49. The apparatus of any one of claims 45 to 48 wherein the second check valve further comprises a guide body movable within the seat body and contacting the valve body.

50. The apparatus of claim 49, when dependent from claim 48, wherein the valve-body- guiding portion is positioned to contact the guide body and limit movement of the guide body transverse to the longitudinal axis during substantially all or all of movement of the valve body during operation of the second check valve.

51. The apparatus of claim 49, when dependent from claim 48, or of claim 50, wherein when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.015 inches.

52. The apparatus of claim 49, when dependent from claim 48, or of claim 50, wherein when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.014 inches.

53. The apparatus of claim 49, when dependent from claim 48, or of claim 50, wherein when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.013 inches.

54. The apparatus of claim 49, when dependent from claim 48, or of claim 50, wherein when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.012 inches.

55. The apparatus of claim 49, when dependent from claim 48, or of claim 50, wherein when the guide body is centered within the valve-body-guiding portion, a clearance between the guide body and the valve-body-guiding portion is less than 0.011 inches.

56. The apparatus of any one of claims 49 or 55 wherein the guide body defines a fluid passage open to opposite sides of the guide body along the longitudinal axis.

57. A hydraulic steering system comprising the lock-valve apparatus of any one of claims 1 to 56 and a hydraulic pump operable to pump hydraulic fluid into and out of the first and second fluid ports.

58. The system of claim 57 further comprising a double-acting hydraulic cylinder comprising a first side fluidly connected to the third port and a second side fluidly connected to the fourth port.

59. A hydraulic steering system comprising the lock-valve apparatus of any one of claims 1 to 56 and a double-acting hydraulic cylinder comprising a first side fluidly connected to the third port and a second side fluidly connected to the fourth port.

60. A watercraft comprising the hydraulic steering system of claim 58 or 59 and a steering device operable to move relative to a hull, transom, or other structure of the watercraft in response to movement of the double-acting hydraulic cylinder.

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